applying the 8d method enhancing quality control effectiveness in the loopline at hcp factory of bosch vietnam co ltd

TECHNOLOGY AND EDUCATIONMINISTRY OF EDUCATION AND TRAININGHO CHI MINH CITY UNIVERSITY OF APPLYING THE 8D METHOD - ENHANCING QUALITY CONTROL EFFECTIVENESS IN THE LOOPLINE AT HCP FACTORY O

Rationale

In an increasingly competitive period of economic globalization, the quality of products and services will define success or failure Businesses are currently focused on ensuring high production, product quality, low prices, and enhanced profitability To do this, organizations must painstakingly and properly execute the assembly line manufacturing process at each level, ensuring compliance with standards and eliminating product defects, hence avoiding the need for rework during production It is critical to use the 8D approach to assess and resolve difficulties and incidents during the manufacturing process This allows the organization to precisely identify and treat the fundamental causes of problems, as well as provide effective solutions

During my past 6-month internship at the HcP factory, Bosch Vietnam Co., Ltd., this factory specialized in producing the CTV pushbelts at Bosch The pushbelts are composed of elements and loopsets The main materials come from specialized steel coils to ensure meeting customer output standards To achieve this, each process in the loopset and element production line must operate optimally and steadily, with the number of defects minimized During the internship, the author had exposure to the Loopset production line and observed a relatively high occurrence of product defects in looplines According to production statistics from the Loopset production department:

Table i: Production results according to plan from April to July, 2023

As shown in the table above, the production lines are not yet truly stable, and they do not achieve the specified percentage of production according to the plan Consequently, it requires additional time for rework to prevent a significant drop in production output This situation has led to an increase in raw material costs and labor costs for overtime production and has a noticeable impact on the production schedule and company

2 revenue Given this situation, identifying the root causes of the productivity decline is of utmost importance From the identified issues at the factory, the author chose the topic "Applying the 8D method: Enhancing quality control effectiveness in the Loopline at HcP Factory of Bosch Vietnam Co., Ltd." for the purpose of research and the completion of the graduation thesis.

Research Objective

Analyse the causes of product defects in the Loopset production line at HcP Factory, Bosch Vietnam Co., Ltd

Applying the 8D method is an effective way to identify the root causes of product defects and address them systematically to prevent future occurrences

Propose solutions to minimize product defects during the Loopset production process of Bosch Vietnam Co., Ltd.

Research Subject and Scope

Research subject: The production and quality control process for Loopsets

- Spatial scope: The research is conducted exclusively within the Loopset production line at HcP Factory, Bosch Vietnam Co., Ltd

- Time scope: From April 15 th , 2023, to Aug 25 th , 2023.

Research Methods

The research is conducted by combining scientific research methods with statistical techniques, comparisons, and analyses From establishing theoretical foundations to practical applications, the study aims to address and clarify the research objectives Moreover, the research places particular emphasis on collecting input from various experts, managerial personnel, and individuals involved in relevant management and operational processes, enriching and enhancing the content of the study

Qualitative research method: Initially, the study provides an overview of relevant theories and builds upon the findings from previous research models concerning the application of the 8D method Subsequently, through on-site observations at the factory, discussions, and research, the methodology is refined and adjusted to ensure effectiveness This process involves developing assessment criteria and modifying questions to better serve the quantitative research phase

Quantitative research method: The survey is conducted by utilizing a questionnaire and a series of direct interviews The aim of this process is to gather information from the labor force directly involved in the production line as well as from various management levels within the line The collected data have been processed and prepared for the next steps in the research process

Method of data collection, analysis, and synthesis: Information is gathered from internal company documents provided This data is then analysed and synthesized, selecting relevant information for the report

Expert opinion method: Consultation is sought from process engineers at the factory and opinions from the guiding instructor.

Structure of Study

Chapter 1: Bosch Vietnam Company Limited Introduction

Chapter 3: Quality Control in the Loopline - HcP Factory

Chapter 4: Enhancing the Effectiveness of Quality Control in the Loopline - HcP Factory

BOSCH VIETNAM COMPANY LIMITED INTRODUCTION

Overview of Robert Bosch GmbH Corporation

Robert Bosch GmbH is a multinational technology conglomerate, founded in 1886 by Robert Bosch in Stuttgart, Germany The company specializes in providing technology and equipment for the automotive industry and maintains business relationships with most global automobile companies Additionally, Bosch manufactures handheld tools, household appliances, clean energy solutions, security systems, smart homes, packaging solutions, construction solutions, mobile solutions, IoT, and Industry 4.0 technologies Company logo:

(Source: Bosch.com) Headquarters: Gerlingen, near Stuttgart, Germany

The Bosch Group comprises more than 725 subsidiaries and has over 400.500 employees in more than 60 countries worldwide To deliver the best products and continuously evolve with the changing global landscape, the Bosch Group employs a staggering 76,100 researchers and engineers across all nations globally

In Vietnam, the Bosch Group's first representative office is located in Ho Chi Minh City Since 2007, Bosch has expanded with two additional offices in Hanoi and Da Nang Bosch established the Transmission System Plant in the Long Thanh Industrial Zone in Dong Nai Province, specializing in producing CVT pushbelts for automobiles The plant started operations in 2008 and commenced production in 2011 Currently, there are over 5,000 associates engaged in diverse business activities at Bosch Vietnam, covering fields such as Mobility Solutions, Industrial Technology, Consumer Goods, Energy Technology, and Construction

About 60% of Bosch's global sales revenue is related to automotive technology Bosch was the first to invent the magneto, which was put to practical use This was the source of electrical ignition during the early stages and was used to ignite most of the first internal combustion engines Bosch's logo to this day symbolizes the component within the magneto Bosch also invented the Anti-lock Braking System (ABS) Over time, Bosch has led in specialized areas such as the Traction Control System (TCS), Electronic Stability Program (EPS), vehicle electronics, oxygen sensors, fuel injectors, and fuel pumps

Bosch's subsidiary, Bosch Rexroth, is an industrial equipment provider Through this division, Bosch offers technology for drives, controls, and machinery operations Another branch of Bosch is Bosch Professional, specializing in handheld power tools and specialized equipment for industrial use

Automation is also one of Bosch's business areas, making it a reputable industrial machinery contractor while also participating in other fields such as the Internet of Things and Artificial Intelligence

Consumer Goods and Power Tools

Bosch has expanded into the consumer goods and construction technology sectors with power tools, thermal technology, security systems, and applications for household use through its subsidiary BSH Bosch and the joint venture Siemens Hausgerọte GmbH Furthermore, Bosch is also a renowned manufacturer of various household appliances Monitoring Equipment

In addition, Bosch provides camera systems and monitoring software for multinational corporations, government agencies, and organizations.

Overview of Bosch Vietnam Co., Ltd

Company Name: Bosch Vietnam Co., Ltd

Address: No 8 Road, Long Thanh Industrial Zone, Tam An Commune, Long Thanh District, Dong Nai Province

Bosch Vietnam Co., Ltd was established in April 2008 with an initial investment of 30 million euros in the first phase and 55 million euros in the second phase in 2015 Bosch Vietnam is equipped with advanced technologies and infrastructure on a 16,000 square meter area By April 2011, the main factory officially commenced operations, specializing in the production of CVT pushbelts for automobiles These products are supplied to automotive manufacturers in the Asia-Pacific region

Figure 1 2: Overview of Bosch Factory in Long Thanh

(Source: Bosch.com) 1.2.2 Vision and Mission

In terms of vision, Bosch is built upon 7 foundational values Firstly, Bosch focuses on delivering results, ensuring a prosperous future, and building a foundation for the company's social initiatives and the Robert Bosch Foundation Secondly, the company acts carefully and responsibly, considering the interests of both the community and the environment Thirdly, Bosch operates on its own initiatives, with a corporate spirit of responsibility and determination to pursue its goals Fourthly, the company openly addresses important issues, fostering trust and credibility in its relationships Fifthly, Bosch treats colleagues and business partners with fairness, considering fairness as the cornerstone of the company's success Sixthly, the company commits only to what it can deliver, accepts binding agreements, and complies with the law in all business dealings Finally, Bosch respects and encourages diversity, viewing it as an essential condition for success These values underpin Bosch's vision and mission, guiding the company's actions and decisions in achieving its goals and contributing positively to society and the environment

In terms of its mission, the Bosch Group is built upon key elements, including:

 Goal-oriented approach: Drawing from the spirit of Robert Bosch, they aim for the sustainable future of the group by ensuring meaningful strength and development while maintaining financial independence

 Motivation: With the slogan "Invented for Life," Bosch aspires to create products that ignite passion, improve the quality of life, and contribute to the preservation of natural resources

 Strategic: They concentrate on customers, shaping change, and striving for the best outcome

 Strength: Bosch relies on its cultural foundation, innovation, quality, and global presence

Bosch establishes its values based on a set of core principles as the foundation for the future, including responsibility and sustainability, openness and trust, fairness, creativity, legality, reliability, and diversity

The departmental structure of Bosch Vietnam is divided into two main branches: Commercial Branch (HcP/PC), under the responsibility of the Commercial Plant Manager, focuses on trade and finance Within this branch, there are four main departments with distinct roles as follows:

- CTG (Accounting): Manages the company's budget and finances

- HRL (Human Resources): Handles tasks related to human resource management and planning, from recruitment for various positions within the company to organizing welfare programs and managing internal matters such as salaries and holidays

- ICO (Information Coordination): Manages information and internal connectivity systems within the company Provides software and network support to engineers and assists in connecting accounts for all employees in the company

- LOG (Logistics): Versees tasks related to shipping, receiving raw materials, transportation, and customs procedures for goods Records consumption reports, arranges suitable storage in the warehouse, and controls warehouse data Additionally, this department updates the status of goods both inbound and outbound

- TGA (Technisch Gewebliche Ausbildung): rovides vocational training alongside a professional education program based on Bosch's training program

Production Branch (HcP/PT), under the responsibility of the Technical Plant Manager, is responsible for overseeing the entire manufacturing process of products In each branch, there are various departments that fulfill specific functions and responsibilities

- MFG (Manufacturing): This department is responsible for producing Continuous Variable Transmission (CVT) belts, starting from manufacturing small components (elements and loopsets) to assembling these parts into complete transmission belts MFG1: Responsible for element production

MFG2: Responsible for loopset production

MFG3: Responsible for assembling elements and loopsets into complete products

- QMM (Quality Management): Ensures the overall quality of the company, including establishing control processes, measurement methods, quality checks from raw material input to finished product output, and quality systems for the entire factory

- FCM (Facilities): Manages physical facilities and equipment, including infrastructure and machinery used in the factory

- HSE (Health, Safety, and Environment): Focuses on safety-related issues in the factory, including employee health and safety, as well as environmental protection, noise, water, and soil pollution prevention within the factory This department also provides safety-related training and skill development for employees

- ETC (Engineering, Testing, and Current Product): Responsible for quality testing of products to ensure the highest quality when they are released to the market

- TEF (Technical Function): Primarily responsible for technical aspects within the factory, covering both software and hardware, including documentation This department is further divided into several sub-departments:

TEF 1: Manages the technical production system and detects errors when issues arise

It also proposes machinery upgrade solutions to enhance operational efficiency

TEF 3: Maintains analyses and provides maintenance strategies for machinery

TEF 4: Focus on promoting digital transformation

TEF 6: Develops training programs to enhance engineers' skills in using support tools

- BPS (Bosch Production System): Manages the production system of Bosch Vietnam's Long Thanh plant

- PRS (Protection Security): Manages plant security and safety

(Source: Human Resources Department) 1.2.4 Product Business Characteristics

The products of Bosch Vietnam Co., Ltd are Continuous Variable Transmission (CVT) pushbelts, and this is the sole product manufactured at this factory In 2008, CVT pushbelts production was initiated at the HcP - Bosch factory located in the Long Thanh Industrial Park Regarding CVT pushbelt, Bosch currently has three factories in three different countries producing this product: the Netherlands (Tilburg), Mexico (San Luis Potosi), and Vietnam (Long Thanh)

Figure 1 4: Continuous Variable Transmission (CVT) pushbelt

Ho Chi Minh City Plant HcP/PC

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The strength of a CVT automatic transmission lies in its ability to efficiently operate the car's engine at all speeds This means the pushbelt must continuously transmit power from the engine to the wheels Furthermore, the fuel consumption of this system is lower compared to manual transmissions by up to 15%, and it also reduces emissions by more than 15% In addition to these benefits, a CVT offers fast acceleration, reduced engine noise, and high adaptability to ensure continuous acceleration

Bosch Vietnam operates on a pull system, manufacturing products based on customer demand The primary market for their products is in the Asian region, with some well- known customers in the automotive industry, including companies such as Sokon, Honda, Jatco, and others

Figure 1 5: Some of Bosch's customers (Source: Bosch.com)

LITERATURE REVIEW

Overview of quality

According to Deming (1986), good quality means a level of consistency and reliability that can be predicted with appropriate quality standards for customers

According to Feigenbaum (as cited by Ta Kieu An, 2004), quality encompasses all the characteristics of products and services that meet customer expectations

Therefore, what exactly does quality mean? According to the widely accepted definition by the International Organization for Standardization (ISO), ISO 9001:2015 standard, quality is defined as the degree to which a set of inherent characteristics of an object meets requirements In simpler terms, a product or service is considered of good quality when it complies with the requirements specified by the customer

According to ISO/TC 176, "Quality management is a comprehensive approach or belief to lead and manage an organization, with the aim of continuously improving performance over the long term by focusing on the customer and addressing the needs of all other relevant parties Quality management is not only applicable in manufacturing but in all fields, and it is not solely the responsibility of the quality department; achieving quality requires collaboration and quality assurance from other relevant departments." 2.1.3 Quality management methods

QC (Quality Control): ISO 9000 defines quality control as "a part of quality management that focuses on fulfilling requirements Quality control can be applied to specific products, to processes that create products, or to the output of an entire organization by measuring overall organizational performance."

Quality control is a process that businesses use to ensure that product quality is maintained or improved It requires creating an environment in which both management and employees are highly conscious of ensuring quality

Quality control aims to ensure that the products produced meet the specifications and characteristics The goal is to identify errors and take corrective actions promptly Quality control helps companies meet customer and consumer demands for better products

QA (Quality Assurance): ISO 9000 defines quality assurance as "a part of quality management that focuses on providing confidence that quality requirements will be fulfilled."

Quality assurance systems are designed to increase customer trust and the company's reputation, while also improving processes and work efficiency, allowing the company to compete better with other rivals

Another way to understand quality assurance (QA) is as a company's process to enhance the quality of its products Many businesses view quality assurance programs as a commitment to stakeholders and customers that the company will provide high-quality products, ensuring a positive experience for users.

The 8D problem solving method

According to Seel (2012), “A problem is generally considered to be a task, a situation, or person which is difficult to deal with or control due to complexity and intransparency

A problem is a question proposed for solution, a matter stated for examination or proof

In each case, a problem is considered to be a matter which is difficult to solve or settle, a doubtful case, or a complex task involving doubt and uncertainty."

Besides that, a problem is also defined as deviations that affect the results in an unexpected way It is uncontrolled and has a significant impact on the outcomes Due to its complexity, solving the problem is one of the priority tasks that all organizations, as well as individuals, need to focus on (Viet Quality, 2019)

Generally, a problem encompasses all the variables that affect the final result, leading to unexpected consequences Problems are omnipresent, occurring for diverse reasons, both external and internal, within every firm These issues within enterprises have a profound influence on operational processes, necessitating prompt resolution to prevent future recurrences Presently, numerous strategies are available to assist businesses in tackling challenges, with the 8D method being a popular choice adopted by many firms Tkác et al (2013) claimed it that:

The 8D method is a tool, the essence of which is a standardized process with an emphasis on facts It also serves to improve products and processes This method can be used in energy sources, means of transport and the transport of material It

13 often happens in practice that statistical methods of quality control are applied to final inspection rather than the management of production processes

Historically, this method was first implemented by the United States Government and was standardized as the 8D process during World War II In the sixties and seventies of the twentieth century, the Global 8D method was popularized by Ford Motor Company

In addition to automotive industry and assembly, the 8D method became the norm wherever a comprehensive and structured approach to problem solving is necessary 2.2.2 Objective

The primary goal of the 8D problem-solving method is to emphasize problem definition through a thorough analysis of root causes, ultimately leading to the formulation of lasting corrective and preventive measures This approach aids businesses in effectively resolving past errors by leveraging accumulated knowledge and charting a clear path for addressing the issue

The below is an overview of some research findings on the benefits that the 8D method brings to businesses:

The use of the 8D report in production allows you to effectively analyse all aspects of the problem before concluding and to collect all critical data, whether about the problem or the proposed corrective measures/solutions All members of the group involved in seeking remedial action are involved in resolving the problem It is suitable for specific, manageable, and well-defined issues The advantage is that it plans specific steps to implement and eval uate the recommended corrective action/solution successfully (Lestyánszka et al, 2023)

According to Krajnc (2012), the 8D report, which focuses on the synergy of interdisciplinary teams and a systematic eight-step approach, can be used to eliminate failures and non-conformities in many industrial sectors, including quality control This method means permanent corrective actions and, by identifying the root causes, prevents their reoccurrence in the future The 8D method used in the organization and presented in this research is an excellent tool for preventing defects from recurring, as indicated by the PPM (parts per million) results but also by related costs

Figure 2 1: Benefit of 8D method brings to organizations

In another case study conducted by Alexa and Kiss (2016), a customer received a delivery with delivery note 114643176 dated 27 June 2015, which led to a customer complaint due to non-compliant packaging with finished goods specifications The improvements made in this case study were later implemented within the company Additionally, a quality assurance analysis in the logistics department of the factory ensured the production of high-quality sensors to prevent defects and establish measures to prevent recurrences Therefor, 8D also assist organizations in complying with specific customer requirements for regulatory concerns

In summary, the 8D problem-solving method offers several advantages for businesses, including establishing a structured and collaborative approach to problem-solving This method enhances individual and team effectiveness in addressing customer concerns promptly and aligns with quality management system requirements It also proactively identifies and prevents future issues, leading to reduced quality costs through process improvement insights and helps organizations meet specific customer requirements, especially those related to regulatory compliance

The 8D approach must be implemented in the following eight steps:

D1: Establishing problem solving team/project

During this step, the primary objective is to assemble a team that possesses sufficient expertise in the product or process where the problem has arisen, in order to devise a solution It is imperative for a problem-solving team to consist of members who

15 collectively possess the requisite knowledge and experience to function effectively Ideally, a team should comprise 5-10 members drawn from diverse departments and involved in the respective process or product

The composition of each team will vary based on the appropriate allocation of members

A complete 8D problem-solving team typically includes the following roles:

The first is Sponsor This individual serves as the project sponsor, usually holding a position of high authority and influence within the company, such as a department head Their responsibility is to ensure the provision of necessary resources for project implementation

The second is Team Leader The team leader is appointed by the Sponsor and assumes the role of leading, managing, monitoring progress, and reporting back to the Sponsor The final is Team Members The remaining team members must possess knowledge or expertise relevant to the problem In most cases, members are selected from different departments, each responsible for specific tasks related to the problem-solving process D2: Describing the Problem

The depiction of the current (actual) state, combined with the examination of variances, unique facets, and associations stemming from the identification of the problem's location, results in the fundamental problem - a refined problem (in terms of time, location, quantity, etc.) that is distinctly separated from unaffected areas The fundamental problem constitutes the transition from the problem-oriented to the cause- oriented part of the PSS

Hence, team members must collaborate efficiently to address the following W questions: Who? What? Where? When? How many? and Is/Is not tool Consequently, the outcome is a thorough, unambiguous, intelligible, and broadly comprehensible depiction of the situation This involves the organization and analysis of the problem grounded in factual information, effectively constraining the issue and distinguishing it from unaffected regions This initial risk assessment entails evaluating the likelihood of occurrence and the magnitude of damage, as well as assessing the impacts on end-users and products D3: Defining containment actions

During step D3, temporary actions should be taken to reduce and isolate the effects of the defect on other products and the production process Several actions can be executed at this step, including isolating the affected area, installing temporary solutions, halting

Related concepts of the study

As claimed by Burke & Silvestrini (2017) put it:

A Pareto chart graphically depicts the ―80/20 rule originally postulated by the Italian economist Vilfredo Pareto to explain economic phenomena The 80/20 rule allows users to identify and focus on the approximately 20% of factors (i.e., columns or categories) that account for approximately 80% of potential problems The purpose of a Pareto chart is to identify those “vital few” areas that account for the largest frequency or relative frequency in a data set and separate them from the “trivial many.”

- On the X axis you have the area of interest (categories) e.g as ward names

- On the left Y axis you have the number of events e.g number of falls

- On the right Y axis you have the cumulative frequency

- Essentially, a Pareto chart is a bar and line graph combined The bars display the number of events per area of interest whilst the line displays the cumulative % of events

- Categories contributing to 80% of the problems are often referred to as the ‘vital few’ whereas the others are labelled the ‘useful many’

Figure 2 3: Example of Pareto Chart

Fishbone is one method or tool in improving quality This diagram also called the cause- and-effect diagram The inventor was a Japanese scientist in the 60s, namedDr Kaoru Ishikawa, he was born in 1915, scientist at Tokyo Japan who is also a chemistry alumnus at the University of Tokyo Thus,the diagram also called Ishikawa diagram

According to Burke & Silvestrini (2017), the purpose of a cause-and-effect digram is to graphically document the analysis of factors (causes) that relate to s single problem or opportunity (effect) Cause-and-effect diagrams are used in problem-solving situations and in general analysis to help the problem-solving or analysis team bothh understand how those factors may cause the given effect and focus on “next steps” in provess improvement

As mentioned previously, a single peoblem or opportunity is identified on the right side of the graphic Major causes often referred to as the 6 Ms: Man (personal or personel), Machine ( hardware/ equipment), Materials, Methods, Measurements, Mother Nature (Enviroment)

According to Mulder, P (2012), the Is/Is Not analysis (KT analysis) is a method used to identify problems by distinguishing what is within the problem area - the factors included in the analysis - from what is not within the scope of the problem Consequently, analysts can exclude those elements from the analysis In simpler terms, Is/Is Not analysis aids the implementation team in selecting which points to incorporate and which to omit This definition serves to concentrate on and precisely define the

21 problem's scope, preventing confusion and deviations from the original requirements, thereby enhancing the effectiveness of the problem-solving process

Figure 2 5: Is/Is not tool and question for describing the problem

(Source: Robert Bosch GmbH 2013) 2.3.4 5xWhy Technique

According to Olivier Serrat (2009), the 5-Why analysis technique is employed when attempting to resolve a problem by repeatedly asking the question "Why?" regarding the issue until the underlying problem is unearthed This questioning process fosters in- depth examination of the matter in a methodical manner To ensure methodical application, three key factors must be adhered to: Firstly, the problem presented must be both comprehensive and accurate; secondly, honesty in answering the questions is essential; thirdly, once the problem is identified, it must be completely addressed This technique was established and refined by Mr Sakichi Toyoda (1867-1930) and has been applied to the production processes of the Toyota Corporation

To further aid in finding the exact root cause, direct cause (TRC) and system related cause (MRC) techniques are used

A direct cause is a cause that can be physically terminated Once the cause is found, the error caused by it can be resolved immediately

System-related causes (MRC) include management, system, personal or organizational reasons It has a cognitive effect on others that makes others not comply with the output requirements

(Source: Robert Bosch GmbH, 2013) 2.3.6 Flow chart

According to Nancy R Tague (2005), "A flowchart, also referred to as a process diagram, serves as a tool for illustrating the systematic sequence of steps within a process." This represents one of seven quality management tools commonly employed by numerous businesses during the process of reporting and analyzing work

Additionally, flow charts are used either to represent a chronological sequence of events (chronology of events, history chart) and/or the chronological change of parameters (flow charts for facts analysis regarding deviations/influencing factors) Both types of descriptions are used, among other things, for condensed documentation and an analysis of differences, special features and changes over the course of a problem situation (Robert Bosch GmbH 2013)

As outlined by Nancy R Tague (2005), the Plan-Do-Check-Act (PDCA) process is a four-step framework for effecting change, and it should be iterated multiple times to ensure sustained and adjusted enhancements PDCA is a widely adopted model for enhancing business processes, and it can also be applied on a smaller scale, such as in each individual step of an improvement process

Figure 2 9: Plan - Do – Check – Act process

QUALITY CONTROL IN THE LOOPLINE - HCP FACTORY

Product information and production process

Currently, the HcP factory exclusively produces CVT pushbelts, primarily serving customers such as Jatco and Honda, etc Instead of using gears, the transmission system in automobiles utilizes a sliding belt between two separate conical pulleys This system adjusts the distance between the pulleys to alter the contact circumference of the belt, resulting in changes to the transmission ratio Furthermore, unlike typical scooters that use rubber belts, the belts used in automotive transmissions are made from steel materials

Figure 3 1: The structure of a CVT pushbelt

(Source: Bosch.com) The drive belt's two basic parts are elements and a loopset which together make up the product's structure Each CVT pushbelt is composed of 19 to 400 interlocking elements, along with two loopsets fastened on both sides of the belt segments About 6 to 12 separate loops are layered together to form a loopset

Figure 3 2: Operating principle of pushbelt

To produce a pushbelt, it is necessary to go through the main stages

(Source: Author analyses) The process of manufacturing a CVT pushbelt consists of three main stages: the element production process, the loopset production process, and the assembly process to complete a pushbelt However, within the scope of this topic, the thesis focuses on researching the reprocessing stages of products that do not meet the requirements in the loopset production process

A loopset is formed from rings to various loops with different sizes The production steps for a loopset are as follows:

Steel sheet Steel pipe Ring Loop Loopset

Figure 3 4: Overview of the loopset production steps

Figure 3 5: The loopset production process

Table 3 1: Detailed description of the process

Pipeline Decoiling Supply the incoming material for loop process

Bending Making pre-bend pipe

Pipe-Washing In order to remove dirt and oil from pipe surface Welding In order to produce the welded pipe

Loopline Laser Cutting Create rings

Rounding the edge of rings after Laser Cutting

Ring annealing To recrystallize, restore material properties, and particle size

Rolling In order to form loops with defined thickness, diameters At the end of this stage, the loop is formed

Loop washing In order to clean rolling oil, dirt on the surface of loops Loop Annealing In order to re-crystallisation, restore material properties, and grain size

Classifying loops based on different sizes Assembling loops into loopset packages

To increase hardness, form Nitriding layer on loop surface Beside, to generate compressive stress on loop surface, improve fatigue resistance properties

Facet Inspection Check the quality of loopset’s facet Store loopsets in trolleys Storage Pre-Assembly Loopsets are stored before trasferred to next process.

Process of loopset quality control

Inspecting the input materials is the initial step in the process of product quality control The raw materials will be inspected by the Purchasing Quality Assurance Department (PQA) Based on the rules established by the issuing corporation and managed and controlled by them, the determination of whether the raw materials comply with IATF requirements or not will be made

The detailed inspection process is as follows:

- Verify and receive material certificates from the supplier via email

- Material certificates will be stored in the local folder of the PQA department

- Material plans will also be created based on production plans and sent to the Purchasing Quality Assurance Department (PQA) and the stockyard

- A packaging list for the batch will be issued in an Excel file, followed by receiving the steel coils and transferring them to the warehouse

- The SAP system will automatically generate stock item numbers using material data from the packaging list to locate the supplier's material certificates in the PQA department's folder

- Material data from the supplier will be copied from the material certificate file and pasted into the Excel database file

- Subsequently, a comparison of results will be viewed in the Excel database file (YELLOW or RED indicating missing or incorrect data from the supplier)

- If there is missing or incorrect data, the PQA department will notify the supplier and request corrections and also block non-compliant batches until feedback is received from the supplier

- Finally, rejected steel coils will be handled and communicated to the supplier The following is the procedure for feeding coils to the production line: A preliminary visual check is conducted to evaluate whether there is any corrosion or other non-conformities, like deformation or discoloration Before unpacking the coil and putting it on the coil rack to be sent to production, this examination is done

The operator will unwrap the steel coil and evaluate its external condition after receiving a production order The steel coil will go into production if no anomalies are found The PQA and QMM3 department will be informed of any differences found during the external evaluation in order to stop the usage of substandard steel coils A quality engineer will then carry out a flaw analysis and decide whether the steel coil satisfies the quality requirements The steel coil will be employed in production if it satisfies the requirements The steel coil will be stored and the supplier will be contacted to address the problem if it doesn't satisfy the requirements

The detailed implementation process is described by the diagram below:

Figure 3 6: Input material inspection flowchart

(Source: Purchasing Quality Assurance department)

Put the steel coil into production

Prevent the non-quality steel coil

Are there any external discrepancies with the coil?

Store the non-quality coil, and contact the supplier

Assess the defects and determine if the coil meets the standards?

Through the quality inspection process of raw materials, specifically steel coils, it is evident that the company places an extremely high emphasis on quality from the very beginning Therefore, to ensure quality, the PQA department has worked diligently with suppliers, setting standards for the composition of steel coils, surface standards, supply quantities, and delivery times to ensure the availability of high-quality input materials for production

Figure 3 7: Operator inspect the quality of steel coils

(Source: Purchasing Quality Assurance department) 3.2.2 Quality control each stage of the loopset production process at LL10

Steel pipe quality inspections are the first step in the product quality management process In order to ensure that every component satisfies the necessary quality requirements before moving on to the following stage, quality control is now applied to each subsequent production step Technicians perform quality checks at each stage of the process, and it is made sure that the product is only moved on to the following stage when quality criteria are fulfilled

The loopsets are moved to the assembly stage where they will be coupled with elements to produce a CVT pushbelt Therefore, it is crucial to ensure the quality control procedure during the loopset manufacturing process Any problems that arise at this point could lead to flaws in the finished product, impacting both the loopsets and the overall quality of the CVT pushbelt This emphasizes how important it is to continue quality management at this point

Quality control is conducted according to the following process:

At the stage of uncoiling steel coils for the purpose of cutting them into steel sheets, the operator will request to receive the raw steel coil from the MSE2 team leader Within a timeframe not exceeding 2 hours after receiving the order from the shift leader, the Logistics department (LOG) will transport the steel coil to the pipeline and place them on the racks

Following that, team members will conduct an external inspection of the steel coil in accordance with the stated requirements They will sign the inspection form and record the steel coil receiving process once the inspection is completed These steel coils will then be meticulously sorted into individual containers built specifically for storage

To protect the steel coils during lifting and use, foam coil cushioning will be stored and then utilized to cushion the inside of the storage containers Each time a coil is replaced, a periodic check will be performed, and any damaged padding will be replaced immediately to prevent quality difficulties during the manufacturing process

During the management process, colored paper will be used to print vital information on the surface of the steel coils, such as the type of steel coil, identification number, date of receipt, and expiration date This information will be precisely affixed to the steel coil storage containers, assisting in the efficient management of storage time The use of colored paper has the additional benefit of eliminating confusion between steel coils of various materials, assuring accuracy and consistency in the operating process

 Inspection of steel sheets (Decoiling and Cutting)

Following the completion of the steel coil uncoiling operation, the machine will begin cutting the coil into steel sheets of identical dimensions Following agreed norms, QC technicians will undertake an external inspection with the naked eye or magnifying glasses They will inspect the sheets for rust, perforations, or warping, as well as any surface scratches

If any of the aforementioned faults are discovered, QC operators will take a sample to the QMM6’s lap to measure the defect's magnitude If the scratch is less than 4 àm in size, it will be accepted as an acceptable fault, and the production process will proceed as usual If the size of the scratch is greater than 4 àm, the steel sheet will be removed The following phase involves quality control engineers determining the root cause of the fault, whether it is caused by the machines or the supplier

If the root cause is attributed to the supplier, preventive measures will be taken to avoid using similar steel coils, and the supplier will be notified about this issue In the case where the cause is attributed to machines, engineers will identify the specific location responsible for the defect and carry out cleaning procedures in the suspected areas After performing the cleaning, if the issue remains unresolved, QC technicians will inform the maintenance department to proceed with repairs Finally, they will document the defect information in a form so that engineers can efficiently monitor the status and progress of this issue’s resolution

 Steel pipe inspection after Bending

After the bending stage, QC operators conducts an inspection of the gap using a Gap Measuring Machine along the pipe's edge

Figure 3 8: Gap Measuring Machine along the pipe's edge

(Source: Author analyses) After conducting gap measurements, if the following cases are identified:

- If the gap is too wide: The operator will proceed to bend it again according to the guidelines and increase the pressure on the bottom mandrel, following operational instructions

- If the gap is too narrow: The operator will bend it again according to the guidelines and simultaneously reduce the pressure on the bottom roller, following operational instructions

- If the pipe edges overlap: The steel pipe will be removed

After conducting measurements using the Gap Measuring Machine along the pipe's edge, the operator will proceed to visually inspect according to the factory standards In the following cases:

- If the two pipe edges are not parallel: The operator will remove the steel pipe

- If there are any surface protrusions on the pipe: The operator will mark the location and then use a specialized cleaning tool within the company to clean the top and bottom rollers of the steel pipe

 Pipe inspection after washing (Pipe Washing)

The quality control results at Loopline 10

Table 3 10: Production output and reject rate statistics from March to July 2023

Reject rate = Reject loopsets/ Output Reject rate limit

Figure 3 10: Chart illustrates defect rate by month

(Source: Loopset production department) From the compiled data table, the author creates a chart comparing the company's reject rate with the company's reject rate limit This reject rate limit has been calculated by the

PT to ensure that the reject rate does not negatively impact the company's revenue Currently, loopline 10 is experiencing a relatively high number of defects, as depicted in the chart above The rows in blue represent the allowable reject rate, while the rows in red indicate the actual number of defects occurring on the line Looking at this chart, the author can clearly see that the actual reject rate significantly exceeds the company's set target, especially in July This indicates that the number of defects on the production

Scrap (loop) reject rate target reject rate

44 line is quite high, and it is imperative to identify the root causes contributing to such a high defect rate

Because of the high defect rate exceeding the set limit, the author focused on gathering data on the number of defective products from each stage in the production line during this period The author has compiled the data in the table as below:

Table 3 11: Number of defects in each stage

Month Stage Frequency/month Defects

Figure 3 11: Pareto chart illustrates the high-defect-generating stages

(Source: Author analyses) Based on the Pareto chart above, drawing a straight line from the right axis at the 80% mark will intersect the cumulative percentage line at a specific point From that point, you can draw a line downward to intersect with the column representing the cause The defects located to the left of this line account for 80% of the results In this case, the Facet and LSDH stages are the ones causing the majority of the defects, with Facet

45 contributing to 70.8% of the defect causes Therefore, the author will focus on analyzing the Facet stage, as it appears to be the primary contributor to the high defect rate After determining the scope of analysis within the Facet stage, the author proceeds to identify common defects in this stage by monitoring production output using the company's production progress monitoring software The number of defects and the names of the defects will be tracked and recorded in detail as follows:

Table 3 12: Defects corresponding to each type of defect in July

Stage Name of defects Quantity

Facet Black defect on loop surface 560

Facet Black defect on loop facet 350

Facet Green defect on loop surface 470

Facet Red defect on loop surface 460

Facet Red dot defect on loop facet 490

Facet White defect on loop facet 1760

Facet White defect on loop surface 1520

Facet Yellow defect on loop facet 3620

Facet Yellow defect on loop surface 4530

Figure 3 12: Pareto chart illustrates the defects occurring in the Facet stage

(Source: Author analyses) The author created a Pareto chart and applied the 80:20 principle to identify which defects appeared most frequently Based on the chart, it is evident that defects accounting for 80% of the causes of the high defect rate are as follows: Yellow defects

46 on the loop surface account for 32.9%, yellow defects on the loop facet account for 26.3%, white defects on the loop surface make up 12.8%, and white defects on the loop facet account for 11% These are considered defects and have a significant impact on the product's functionality Therefore, it is crucial to pay special attention to these defects and identify the root causes for corrective actions to reduce the monthly defect occurrence.

Factors affecting quality control at Loopline

Input raw materials play a crucial role in the production process The quality and availability of these raw materials can significantly impact the quality of the final product Ineffective management of incoming materials by a business can lead to waste and increased production costs

The consequences of poor or inefficient incoming materials can have a ripple effect on the product quality throughout the entire production line Customers may become dissatisfied with the product and switch to competing alternatives This can impact the revenue and future financial prospects of the business Therefore, carefully managing incoming materials and ensuring their quality is of utmost importance to ensure the success and sustainable growth of the enterprise

If the raw materials do not meet the required quality standards and suppliers fail to meet the specified delivery times, it will directly impact the company's production plans Therefore, assessing and selecting suppliers is of utmost importance for the business To ensure the quality of input raw materials, they need to identify important factors such as:

- Material type: The company specifies that the material used is stainless steel coils

- Thickness and dimensions: The thickness and dimensions of the steel coils are crucial to ensure efficient transportation, processing, and usage

- Material poperties: Material properties such as hardness, strength, ductility, heat resistance, corrosion resistance, etc., need to be analysed These properties will affect the lifespan and performance of the steel coils

- Purity: Checking and ensuring high material purity is essential in input materials to avoid impurities or contaminants that could affect the production process and the performance of pushbelts

- Reliable supply source: Choosing a reliable and high-quality supplier ensures a dependable source of input materials for stainless steel coil production With the quality and reliability of their product, NIPPON STEEL fulfills all of Bosch's highest standards and requirements This collaboration ensures that Bosch's products meet the highest quality and performance standards in the automotive industry

In case of product quality issues on the loopline, the PQA department plays a crucial role in investigating the root causes of these issues If the input materials do not meet the required standards set by the company, it can adversely affect the quality of the entire production line and potentially lead to the rejection of all products already manufactured This can result in lost productivity on the line, wastage of raw materials, and impacts on delivery times or even order delays

The human factor plays a crucial and top-priority role in the production process This is of particular importance in ensuring the quality of the product Because all production activities rely on the contributions of individuals, correctly assigning roles and tasks that align with each person's capabilities becomes a valuable resource, supporting the achievement of the company's production goals Thanks to this, the company has the ability to reduce unnecessary costs, minimize inventory levels, mitigate the risk of product defects, and optimize the utilization of human resources

< 6 moths 6 months -1 year 1-2 years 3 years

(Source: Loopset Production Department) The essence of the production process at the factory primarily relies on the combination of machinery and human labor Machinery takes center stage, but for it to function, it requires the intervention and participation of workers to perform the necessary tasks to create the products Therefore, plant director requires that workers have to have a

48 fundamental understanding of machine operation, production stages, and product quality requirements to ensure they meet the production goals of the factory

However, statistical data indicates that currently, in the loopset production lines, there is a total workforce of 185 individuals Among them, 18 workers (constituting 9.73%) have been employed for less than 6 months, 56 workers (making up 36.22%) have been working for 6 months to 1 year, 96 workers (representing the highest percentage at 51.89%) have been employed for 1 to 2 years, and 15 workers (comprising 8.11%) have been with the company for over 3 years There are some long-tenured workers, their proportion is relatively low Especially, a significant proportion of workers have been recruited within the past 2 years These are the employees who have become familiar with the operational stages and production activities

In general, the labor force at the factory is currently stable, with no significant increase in new workers, and experienced workers comprise a high percentage However, this situation still does not guarantee that the operational process have been standardized, leading to a gradual increase in product defects on the production lines

In addition to focusing on the human factor, the contribution of machinery and equipment is also considered one of the crucial factors in the production process The stability and efficiency of machinery play a vital role in enhancing production output, ensuring product quality, and facilitating the smooth flow of products Since the factory's capabilities primarily depend on machinery, a malfunctioning machine, especially those with extended maintenance and repair times, can impact subsequent production process Therefore, the maintenance and upkeep of machinery play a crucial role The maintenance process should encompass the control of all machine operations, monitor, and update regularly to ensure that all machines operate stably This ensures that production activities are carried out efficiently and are not disrupted due to machinery malfunctions

The maintenance engineering workforce is divided according to the types of machines, with each engineer responsible for a different type of machine The maintenance department is further divided into mechanical engineers and electrical engineers Machines in the production lines are continuously monitored to ensure their stable operation for manufacturing However, there is still no specific plan in place to

49 coordinate with the production schedule, determining whether to temporarily halt the production line for maintenance or continue production This lack of coordination may lead to insufficient time for maintenance and production Currently, the machinery operates at a high frequency and has been running continuously for many years, making breakdowns unavoidable These breakdowns can impact production time and product quality When a machine issue is detected, engineers quickly investigate the root cause, and the maintenance technical team promptly repairs the machine to bring it back to normal operation

In general, the maintenance tasks at the factory operates relatively stably However, the detection of abnormal machinery is still not carried out promptly, and timely action is needed The maintenance plan has not been effectively aligned with the production schedule, which can have an impact on production time and output volume

Table 3 14: Number of loopline 10 downtime incidents in July

No Name of machine Quantity Number of downtime incidents

(Source: Maintenance Department) Currently, loopline 10 is using 34 machines and has recorded a total of 174 instances of machine downtime in July The average duration for each instance of downtime is 5579 minutes Downtime is measured as the total time the machine is not operational,

Assessment of the current situation at the loopline

The company has been focusing on product quality improvement in recent years by implementing various measures:

Firstly, Clean and well-ventilated shopfloor: The shopfloor is consistently kept clean and well-ventilated to create a comfortable working environment for employees Daily cleaning processes and periodic cleaning and storage tasks contribute to work efficiency, product quality, and employee concentration

Secondly, Efficient departmental coordination: Various departments within the factory maintain smooth coordination, with clear task assignments and authority divisions This ensures uninterrupted production processes The typical production line structure comprises one supervisor, 12 operators, and 5 QC technicians stationed at the end Process engineers, line engineers, and quality engineers continually monitor and provide detailed work instructions, which are readily posted at each stage for easy reference by operators

Thirdly, Efficient shopfloor layout: The layout of the shopfloor at the HcP factory is well-planned and efficient The close arrangement of stages such as Decoiling, Cutting, and Bending, along with the organization of steel pipe trays minimizes transit time Machines and workstations follow a linear design, with raw materials at the start, a supervisor's desk, and the quality control room for loopset technicians at the end This streamlined layout ensures a smooth product flow, making it easy for operators to

51 transport finished products and for supervisors and engineers to monitor the production line's operation effectively

The writer identifies several limitations in the production process that impact product quality and factory process optimization:

Loopline 10 is experiencing a relatively high number of defects the author can clearly see that the actual reject rate significantly exceeds the company's set target This indicates that the number of defects on the production line is quite high, primarily caused by yellow and white color errors in the loopset

The majority of the workforce consists of operators who have been working for 1-2 years During this period, these operators have become familiar with the process and tasks Due to the lack of precise execution, the reject rate remains relatively high This pointed that the effectiveness of employee training is still not optimal Operators lack enthusiasm for training courses, and the assessment of the working proficiency of the operators is not closely monitored Furthermore, operators often lack concentration during their work, failing to detect abnormalities promptly They engage in private conversations with other operators from different processes while performing their tasks The workspace arrangement and organization are not tidy and logical, leading to confusion regarding the loops during operating The improper workspace arrangement not only poses the risk of errors but also wastes time

The equipment and machinery in the workshop are also important aspects that need to be examined and addressed Most of the equipment and machinery in the workshop have been transferred from a factory in the Netherlands to the HcP factory These machines have typically been in use for over 5 years, leading to unstable operational efficiency and increased production downtime for repairs This adversely affects production efficiency and delivery schedules The entire loopline's performance relies heavily on the stability of these equipment and machinery Therefore, choosing the appropriate maintenance approach is crucial This will enable the workshop to respond flexibly to sudden breakdowns in machinery, especially critical machines that play key roles in the production process

The management experience of shift leaders plays a critical role in the production process Shift leaders oversee the entire production line, monitor the operators,

52 production output, product quality, material status, and oversee the storage of finished products in the centralized warehouse Additionally, shift leaders are responsible for monitoring the stability of the stages of process on the loopline When a supervisor effectively manages their responsibilities, they gain a comprehensive overview of the current loopline, maintain stability on the line, and ensure a well-organized workforce Conversely, poor management by a shift leader can lead to delayed response to on-line incidents, reduced line efficiency, and improper workforce arrangement Most of shift leader are experienced operators who have been promoted However, they may lack certain skills required to maintain line productivity and address unexpected issues They may also lack mechanical knowledge to temporarily resolve issues without affecting the quality of the finished product In cases of problems, shift leaders may have to stop the machines and wait for process engineers or maintenance engineers to arrive and resolve the issues This results in significant production downtime and adversely impacts line productivity

ENHANCING THE EFFECTIVENESS OF QUALITY CONTROL IN

Applying the 8D method to identify the root causes of yellow defects on loopsets

Firstly, the project manager should create a specific timeline for the project tasks An author has created a plan for the project as depicted in the figure below:

(Source: Author analyses) 4.1.2 D1_Forming a Team

In step D1, the writer will proceed to form a team and select team members to participate The members of this project team include engineers from relevant departments involved in assessing the issue: Quality, Maintenance, Production The project leader is responsible for addressing the problem is the MSE2 process engineer, who is in charge of resource support, reporting to the management board, and resolving any issues related to other departments (if applicable) They will collaborate with the head of that department to select team members for participation

The team comprises the following specific members as below

No Name Department Position Role in project

1 Phan Thanh Phong MSE 2 Group leader MSE 2 Sponsor

2 Nguyen Duy Thinh MSE Process Engineer Project Leader

3 Nguyen Anh Tuan MSE 2 Line Engineer Member

4 Ngo Xuan Cuong MSE 2 Process Engineer Member

5 Doan Quang Minh MSE 2 Process Engineer Member

6 Tran Ngoc Minh MSE 2 Shift Supervisor Member

7 Phan Thanh Tin TEF 3 Maintenance Engineer Member

8 Do Ngoc Tuan Anh TEF 3 Maintenance Engineer Member

(Source: Author analyses) 4.1.3D2_Describing the Problem

In July, the reject rate on loopline 10 suddenly increased The defect positions on the loopsets were typically found on the facet top of the loopset, the facet top of the loop, the facet bottom of the loop, the facet bottom of the loopset, and on the surface of the loopset

Table 4 2: Summary of yellow defect locations The locations where defects appear Illustrative images

Yellow defect on the facet top of the loopset

Yellow defect on the facet top of the loop

Yellow defect on the facet bottom of the loop

Yellow defect on the facet bottom of the loopset

Yellow defect on the surface of the loopset

(Source: Author analyses) The author and the project team collect data and analyse the statistics for each type of defect using Pareto charts

Table 4 3: Frequency statistics of defect locations

Figure 4 2: Pareto chart for the locations of defects

The author creates a pareto chart and applies the 80:20 principle to determine which locations detects the most defects Based on the chart, it is observed that the "Facet Top

- Loopset" (56.5%) and "Facet Top - Loop" (33.4%) together account for 89.9% of the defects Therefore, operators and process engineers should pay special attention to these locations on both the loop and loopset The next step is to investigate why yellow spot tend to occur in these areas Below is an Is/Is Not analysis table to clarify the issue further

Table 4 4 Is/Is Not analysis table for addressing yellow spot on Loopline 10

What What is the issue occurring?

There are yellow spots on the loopline

There is no spot on the conveyor

Where Where is the issue occurring?

On the facet top, facet bottom, and surface of the loopset

It doesn't appear on the loopset

How How was it detected?

The reject rate is high Operators inspect the loopset and make the discovery

When When was it detected?

At the end of the production process

(Source: Author analyses) After analyzing the Is/Is Not, the team identified clear differences between the state of the issue occurring and the normal operational state on loopline Firstly, there are yellow spots on the loopset compared to the usual state on the conveyor Secondly, the spots occur at the facet top, facet bottom, and surface of the loopset The issue is attributed to an excessive number of defective products on the line, exceeding the control limits, resulting in a high defect rate The defects are detected at the end of the production process

Therefore, the team concludes that the fundermental cause of the yellow spot on the loopset and loop is the presence of foreign objects or chemical leakage on the conveyor, resulting in yellow defects

To prevent the occurrence of yellow spots on loop and loopset, the project team has provided temporary work instructions to address this issue: Engineers instruct the operators to clean defects when yellow spots are detected on the loop

The team proceeds with root cause analysis The causes are represented on a fishbone diagram During the construction of these causal diagrams, the team gathers raw data from its members regarding what causes the defect From the input gathered from team members, the team has identified the factors causing the defect:

Figure 4 3: A fishbone diagram identifies the causes of yellow spots

(Source: Author analyses) Machine: Most of the loopsets are produced by machines, so maintenance significantly impacts the quality of the loopsets Inadequate maintenance planning and frequent machine breakdowns are factors that contribute to a high reject rate

Human: Because the product requires high precision, and certain characteristics of the product need inspection after each stage, operators play a role in indirectly contributing to reject rate Although the influence of human factors on causing defects is much less than that of machines, they still play a part in product defects They can be influenced by objective or subjective factors that may lead to defects Their subjectivity can result from lack of concentration, new operators, lack of experience, or inadequate training

Frequent machinery breakdowns Non-standard input quality

Lack of guidelines for tool and equipment usage

Failure to update work instructions

Failure to read work instructions carefully

Poor implementation of 5S Low work morale

Lack of adequate training for operators

Yellow spots on the facet top of loop and loopset

Material Non-standard packaging of raw materials

Failure to detect product defects can have repercussions on subsequent stages of loopline process

Method: At Bosch, work instructions are issued in a clear and specific document for operators to read and thoroughly understand each operational procedure However, deficiencies in standardizing tool and equipment usage, as well as inadequate implementation of the 5S methodology, result in a lack of control and create gaps that lead to product defects Additionally, the lack of continuous updates to work instructions to align with actual situations means that operators may not know how to address issues when product defects are identified, contributing to a high number of defective items

Material: The quality control of incoming raw materials and the proper storage of materials in the warehouse are also factors that influence the quality of loopsets

The team is using a Pareto chart to identify the most frequent causes of defects based on production monitoring software The author collected data on the quantity of defective products and the characteristics of these defects in the Facet process during a work shift in July This data will be used to determine the root causes of the defects

Table 4 5: Frequency statistics of causes for yellow defects in products

Causes Number of product defects per work shift

Figure 4 4: Pareto chart of product defects

(Source: Author analyses) From the chart, it is evident that the primary cause leading to yellow defects on the facet top of the loop and loopset is machinery The author will continue to investigate the process where these yellow defects are occurring in loopset production

Figure 4 5: Identification of high-risk areas for defects

(Source: Author analyses) The positions on the machine where defects can occur are in the Sorting stage (vision lighting , Z-axis), at station 50 (roller conveyor); in the SQC stage (ST6, ST7: gripper

60 machine, linear axis, and xy cylinder) Therefore, the team members propose two main hypotheses that may occur:

Hypothesis 1: Contaminants (dust, oil, grease) adhere to the top loop, which is then moved through the LSDH stage Defects are found in this area

Hypothesis 2: Contaminants (dust, oil, grease) adhere to the bottom loop, which is rotated and assembled into a loopset Then the loopset is moved through LSDH, defects spread to the surrounding loops

Figure 4 6: Branch of the first hypothesis causes yellow defects on the loop

(Source: Author analyses) The project team proceeded to conduct an evaluation for hypothesis 1: Contaminants (dust, oil, grease) adhering to the top loop, which is then moved through LSDH stage, and defects are found at the edge

Table 4 6: Details of the loop inspection process for hypothesis 1

Gripper Sample: 3 halves of a loopset Results: 1 half is black, 2 halves are yellow

- Contamination on the above gripper causes black defects and does not cause yellow defects (1 st half)

- Contamination inside the gripper possibly cause yellow defects

- Oil from the linear axis of gripper potentially cause defects (3 rd half)

Results: 1 half of the loopset is yellow

Conclusion: Oil from the linear axis may cause defects

Cylinder Sample: 4 halves of a loopset Results: None of the loopset halves are yellow

Conclusion: Oil from the cylinder does not cause yellow defects Station

Results: None of loopset half of yellow

Contamination from ST6 does not cause yellow defects

Applying the 8D method to identify the root cause of white defects on the loopset

According to the statistical report, defects significantly impact the high defect rate exceeding the control limit, with the majority being white defects appearing on the loopset To reduce the defect rate caused by white defects, the project team has also implemented the 8D methodology to identify the root cause

Firstly, the project manager should create a specific timeline for the project tasks An author has created a plan for the project as depicted in the figure below:

(Source: Author analyses) 4.2.1 D1_Forming a Team

In step D1, the author will proceed to form a team and select members to participate The team members include engineers from each department related to incident evaluation, including quality, maintenance, and production The project team leader will be responsible for guiding the team and will be selected from the process engineers in the production department

The team comprises the following specific members as below

No Name Department Position Role in project

1 Phan Thanh Phong MSE 2 Group leader MSE 2 Sponsor

2 Nguyen Duy Thinh MSE Process Engineer Project Leader

3 Nguyen Anh Tuan MSE 2 Line Engineer Member

4 Ngo Xuan Cuong MSE 2 Process Engineer Member

5 Doan Quang Minh MSE 2 Process Engineer Member

6 Tran Ngoc Minh MSE 2 Shift Supervisor Member

7 Phan Thanh Tin TEF 3 Maintenance Engineer Member

8 Do Ngoc Tuan Anh TEF 3 Maintenance Engineer Member

(Source: Author analyses) 4.2.2 D2_ Describing the Problem

At the beginning of July, a white defect was discovered on the surface of the loopset during the surface loopset inspection process (Facet Inspection procedure)

Figure 4 10: White defect on the loop surface

(Source: Author analyses) The team is conducting an Is/Is Not analysis to analyse the encountered issue

Table 4 11: Is/Is not analysis table for analyzing the encountered issue

What What is the issue? There are white spots during the production process

There is no white defect

Where Where is the issue On the surface of the loopset

There is no specific spots on the loopset How How was it detected? The reject rate is high Notify from the loopset inspectator When When was it detected? End of the production process

(Source: Author analyses) Therefore, the team concludes that the fundemental problem is the presence of a foreign object causing white spots on products

To prevent the occurrence of white sopts on the loopset, the project team has taken containment actions to minimize the increase in the number of defects Specifically, the operators cleaned the machines in the Sorting stage and the conveyor rollers in ST50 according to the engineer's instructions Subsequently, a surface inspection of the loopset was carried out in the Loop Washing stage, and the surface returned to normal with no white spots detected

After conducting research, the project team proceeded to investigate the root causes of the issue These root causes are documented in the table below:

Table 4 12: Summary of root causes for white defects

White spots on the loopset

Using white protective gloves causing white residue to adhere to the surface of the loopset

Screws and machine frame colliding with the Mica cover during Sorting, causing dust to fall onto the rollers (Collision among components inside the machine)

Influence from preceding staegs, and some implementation methods not being correct

(Source: Author analyses) Material: Employees wearing white gloves when handling the loop, causing white fabric fibers to adhere to the loop's surface

Machine: Components of the machine are still assembled and arranged improperly, leading to collisions among the machine's parts

Method: Some methods from previous stages were not executed correctly (Loop Washing satge)

Subsequently, the team conducted a practical examination of the potential causes, and all the previously identified causes that were observed on the production line The team proceeded to ask deeper questions using the 5xWhys tool to identify the root cause

Table 4 13: 5xWhys question for white defects on the loopset

Why are there white spots on the loopset?

Because there are foreign objects causing the white spots on the loopline

Why are there foreign objects causing the white spots on loopline?

Because white gloves were used during operation (TRC)

Why were white gloves used during operation?

Because there were no specific regulations regarding the use of gloves (MRC) Screws and the machine frame collided with the Mica cover during

Why did the screws and machine frame collide with the

Sorting, causing dust to fall onto the rollers

Mica cover during Sorting, causing dust to fall onto the rollers?

Because the design of the guide bar couldn't properly maintain the position of the Mica cover with the machine frame and guiding screws (TRC)

Why couldn't the design of the guide bar maintain the correct position of the Mica cover with the machine frame and guiding screws?

Because there were no standard regulations for the design of the guide bar (MRC)

Residual contamination on the loop after Loop Washing

Why is there residual contamination on the loop after Loop Washing?

Because the chemicals in the tank at ST1 did not spray effectively on the loop after an extended period of inactivity (TRC)

Why did the chemicals in the tank at ST1 not spray effectively on the loop after an extended period of inactivity?

Because there were no standard regulations for manual spraying/agitating chemicals after stopping Loop Washing (MRC) (Source: Author analyses) After conducting the 5xWhys analysis, the team has identified the root causes of the issue The TRCs are the use of white gloves during operation, chemicals in the tank at station 1 not spraying effectively on the loop after stopping loopline, and the design of the conveyor not maintaining the correct position of the Mica cover with the machine frame and guiding screws The MRCs are the lack of specific glove usage regulations

71 and the absence of standard regulations for the design of the conveyor, as well as the absence of standards for manual chemical spraying/agitation after stopping the Loop Washing machine

4.2.5 D5: Defining corrective actions and proving effectiveness

Table 4 14: Corrective actions for each root cause

No Root causes Corrective actions

1 Operator's white gloves coming into contact with the roller

Operator's white gloves coming into contact with the roller [during cleaning/maintenance]

Switch to using blue rubber gloves

2 Screws and the machine frame colliding with the Mica cover during the

Sorting stage, causing dust to fall onto the rollers

The design of conveyor cannot properly maintain the correct position of the Mica cover with the machine frame and guide bar

Clean all Mica dust from the roller at the Sorting stage

- Add a stopper button to the edge of the cover to prevent it from colliding with the machine frame

- Remove screws from the guide bar of the Mica cover

3 Residual contamination on the loop after Loop

Chemicals in the tank at ST1 not spraying effectively onto the loop during the acceleration phase after an extended stoppage

Manually spray at station 1 for 30 minutes before switching to automatic operation

Figure 4 11: The stopper button on the edge of the cover

(Source: Author analyses) 4.2.6 D6: Implementing corrective actions and tracking effectiveness

To monitor the implementation process and track progress for these solutions, the team also utilizes the PDCA method and reports the status on the system

Table 4 15: Progress monitoring and effectiveness tracking for corrective actions

No Actions PIC Due date Status

1 Switch to using blue rubber gloves Process

2 Clean all the mica dust on the roller at the Sorting stage

3 Add a stopper button to the edge of the cover to prevent it from colliding with the machine frame

4 Unscrew on the guide bar of the mica

5 Manually spray at ST1 30 minutes before running the small assembly line for picking up at ST7

(Source: Author analyses) After implementing the corrective actions, each individual in every department will carry out their responsibilities diligently, and the team members will record the number of loopset defects reduced to within the control limits

After identifying the root cause and preventive actions, the author compiles them into the table below:

Table 4 16: Preventive actions for each root cause

No Root causes Preventive actions

1 White gloves of the employees come into contact with the roller [during cleaning/machine repair]

The current cleaning and transportation instructions still do not address the risk of causing this issue

Cleaning the conveyor during transportation

There are no standards prohibiting the use of white gloves touching the roller

Sharing the update on using blue rubber gloves for all engineers to confirm

2 Screws and machine frame come into contact with the mica cover during the Sorting stage, causing dust to fall onto the roller shaft

The risk of mica dust adhering to the ring and causing white marks is not yet known

Update the reaction plan for the white spots occurring in the Sorting stage for inspecting and cleaning the roller

3 Residual contamination on the loopset after the

There are no established standards for manual spraying or chemical agitation after

Loop Washing stage stopping the Loop Washing machine

Suggestion to enhance quality control efficiency in the loopline

The operators responsible for machine operations are directly responsible for producing the loopsets and are also one of the primary factors influencing product quality Therefore, the author has several proposals:

For long-term employees: This group is experienced workers who are familiar with the specific procedures, skilled in their roles, and accustomed to the factory environment Therefore, the company should provide training on fundamental knowledge about quality and production process, helping them understand the importance of quality for themselves rather than just for the company Additionally, the operators should be trained about machine configuration to enable a better understanding of principles of machines As a result, they will be able to identify signs of deviations to address issues promptly before these issues become worsen and more challenging to resolve

If any operator identifies discrepancies from the stable state, they should notify engineers to resolve the issue promptly The company will then provide a bonus in their monthly salary as an incentive for their professional development In addition to the bonus, operators will be recognized with the title of "Quality Hero" and their image will be featured in internal company communication channels to honor their achievements For new employees with less than 6 months of experience: These are new labor forces without prior knowledge or skills, so providing comprehensive training from the ground up is essential During their training, it is crucial that the trainers make them fully understand each step they performed including the standards for each step This

74 approach will foster a greater awareness and responsibility in the operators regarding their tasks, preventing non-standard or rushed operations

For shift supervisors and quality technicians: The company should create training sessions with internal experts to provide new knowledge or skills that they may be lacking For instance, employees should be trained in quality-related skills such as problem-solving, root cause analysis, and the elimination of factors causing disruptions, the way to define preventive actions This approach helps prevent potential issues that could affect product’s quality

The training costs are virtually nonexistent because it involves internal training without the involvement of third parties The trainers will be experienced engineers specialized in the manufacturing field, providing a foundation for the workforce to self-improve their skills and enhance their personal value

4.3.2 Perfecting the 5s implementation at the factory

The goal of implementing the 5S standard at HcP factory is to establish a standardized system for all employees, creating uniformity throughout the entire facility Additionally, this standard focuses on engineers, operators, and technicians to optimize the work environment, improve work efficiency, and minimize unnecessary errors

5s standard for floor marking: Floor marking is carried out to create clear delineation for areas or positions with specific purposes The use of different colors for floor marking tape serves the function of emphasizing distinctions between various usage purposes The implementation involves clearly defining the area and applying the following color standards:

Table 4 17: Area designation based on color standards Color standards

5cm Moving equipment: Various types of carts, forklifts, display boards 5cm Used for quality-approved components/parts:

- Standard finished goods ready for delivery to customers

- Raw materials, prepared or in-use semi-finished products

- Components ready for the next process

- Suggested: for use with emergency equipments 5cm - Components awaiting repair or re-manufacturing

5cm - Scrap, defective goods, waste bins, and trash

- Used waste materials (solid or liquid)

- Firefighting equipment (fire extinguishers, oil spill containment tools)

5cm Hazardous and toxic area:

- Hazardous raw materials and chemicals

- Furnace and machinery areas with potential for movement

5cm Suggestion: Noisy area, wearing headphones required

(Source: Author analyses) Guidelines for using detail marking tapes:

- Areas requiring headphone usage for safety distance (sky blue tape)

- Firefighting equipment areas (red tape)

- Furnace areas (high temperature), hazardous areas (yellow/black tape)

Figure 4 12: Floor marking distance regulations

A distance of 15 cm from the object to the tape is required If the distance between the object and the tape is too small, it may damage the tape due to contact with the wheels of the cart

5s standard for labels: Labels represent content such as "Pass/Fail" or the status of a material//tool/equipment/machine or a stage The purpose of these labels is to provide visual observation of the current state of the object These labels are laminated in plastic and placed directly on the material//tool/equipment/machine or a stage, following specific color standards:

Table 4 18: Color standards for labels

Pass Hold, Pending inspection, or Waiting for repair Reject

For temporary purposes but not categorized under the 'Green,' 'Red,' or 'Yellow' label item list

(Source: Author analyses) 5s standard for labels on machines and equipments: All non-fixed machines and equipments in the department must have labels, and they should have a designated storage location The purpose is to identify the machines and equipments belonging to a specific department, its associated process, and its storage area Beside, it is easy to control of machines and equipments within the department, ensuring proper usage and storage The implementation method is as follows:

- Identify the equipment's serial number and the owning department

- Determine which process the machine or equipment is used for, if necessary

- Affix a label to the machine or equipment, specifying its storage location

- Use laminated labels with black text on a white background, using the Bosch Office Sans font

- Place the label in the middle of the machine or equipment for easy observation

Figure 4 13: Expandable label for the cart, board

In addition to the general 5S regulations issued at the factory, there should also be reminder signs about 5S compliance in the workplace, especially at the production lines Furthermore, the training on 5S knowledge should be enhanced at the factory, establishing teams of employees with expertise to regularly inspect and assess 5S compliance in the production lines The 5S supervision team should create reminders in case of non-compliance

Enhancing 5S not only helps eliminate waste factors but also increases overall efficiency in the production process This contributes to preventing incidents, minimizing defects in the production process, and improving the quality of products Therefore, it can create customer satisfaction and enhance the ability to maintain or strengthen existing business relationships

4.3.3 Improving machine maintenance and service operations solutions

The majority of manufacturing operations in the shopfloor are closely related to M&E Maintaining this stability helps ensure a smoother production process and reduces the occurrence of defects in products

The maintenance engineers will be responsible for developing the training content and enhancing the technical skills of maintenance technicians After the training, engineers will conduct exams to review the technician’s knowledge If a technician scores below 70% on the completion exam, they will be considered as not having completed the training course and will be required to retake the course Additionally, every quarter, maintenance technicians must complete an assessment to ensure they understood and knew how to handle each type of machine These assessments will be designed and evaluated by maintenance engineers

Furthermore, maintenance activities will be planned specifically for each machine on the production line Preventive maintenance plans will be scheduled for machines on the production line Every 18 months, a comprehensive machine overhaul will be conducted

78 to assess the current status of the machine, the status of its components, and determine if any components need replacement or repair The purpose of the comprehensive overhaul is to maintain the stable operational status of the machine and take timely action if there is a risk of breakdown After completing maintenance, the technicians and engineers will perform test runs and adjust technical parameters if any errors are detected Maintenance technicians must record their work according to the form provided by the engineers

Table 4 19: Maintenance form for machines

No Components Week Describe Status

(Source: Author analyses) Afterward, the engineers will review these forms to understand the status of the machines and identify which components or parts require appropriate corrective actions

Steel coil inspection criteria

Annealing Ủ tiêu chuẩn Standard annealing

Surface treatment Removing lubricating oil layer

(Source: Input Quality Inspection Department) Appendix 2: Identified Chemical Components

(Source: Input Quality Inspection Department) Appendix 3: Steel Coil Production Process