Applying lean tools to identify and eliminate waste in the stone production process at 350t h stone crusher at dong phong co , ltd

Trang 1 TECHNOLOGY AND EDUCATIONMINISTRY OF EDUCATION AND TRAININGHO CHI MINH CITY UNIVERSITY OF S K L 0 0 8 6 9 1LECTURER: M.E NGUYEN THI MAI TRAM STUDENT: NGUYEN NGOC TOANGRADUATION D

Rationale of the study

In today's competitive economy, businesses must comprehensively prepare to thrive, particularly by meeting customer needs in both product quality and timely delivery The adoption of scientific management tools in production is increasingly crucial, especially as globalization intensifies competition, particularly from foreign corporations Vietnamese manufacturing companies often struggle with issues like excess inventory, inefficient human resource allocation, and production bottlenecks, leading to significant waste Continuous improvement in production processes is essential for enhancing competitiveness and satisfying customer demands Dong Phong Co., Ltd., operating in the stone mining sector, faces similar challenges, including long wait times for dump trucks, inadequate maintenance leading to machinery shortages, and overproduction that results in excess raw materials and finished goods These inefficiencies hinder the company’s ability to meet customer requirements and escalate production costs To address these issues, the author proposes the topic “Applying Value Stream Mapping to identify and eliminate waste in the 1x2 stone production process at the 350T/H stone crusher at Dong Phong Co., Ltd.” to gain a comprehensive understanding of the stone crushing process.

The current state value stream map of Dong Phong Co., Ltd has been analyzed to identify inefficiencies and waste within its stone manufacturing process By pinpointing these areas of waste, targeted solutions can be proposed to enhance operational efficiency and streamline production.

Purpose of the study

The primary goal of this project is to utilize Value Stream Mapping to identify the eight types of waste present in the stone production process at the 350T/H stone crusher By analyzing these inefficiencies, we aim to propose effective solutions that will help the company minimize waste and enhance the overall efficiency of its stone manufacturing operations.

- Understand the company’s current stone production process

- Apply the value stream mapping tool to assess the rationality of the process and detect existing waste in the stone production process

- Evaluate the effectiveness and limitations and propose solutions to improve the stone production process at the company’s 350T/H stone crusher.

Object and range of study

Research subject: stone manufacturing process at Dong Phong Co., Ltd

Research scope: Data is taken from the company in the course of 3 years (2018 to 2021) Research area: stone production site at 3A quarry of Dong Phong Co., Ltd.

Research methods

Quantitative research methods: data collection, statistical information on the production process, Value Stream Map, Pareto chart, SIPOC diagram, SPSS, Minitab Workspace, Minitab 19, Excel, Process Flow Chart, Yamazumi chart

The study utilizes both primary and secondary data to analyze the stone production process at the 350T/H stone crusher plant located in quarry 3A Primary data was gathered directly from the site, focusing on key metrics such as cycle time, takt time, and waiting time Additionally, secondary data, including work orders, reports, and historical statistics from relevant departments, was examined to provide a comprehensive overview of the company's stone production operations.

Structure of the study

The study is structured into four chapters:

Chapter 1: General introduction about Dong Phong Co., Ltd

Chapter 3: The actual situation of the stone crushing process at 350T/H the crusher of Dong Phong Co., Ltd

Chapter 4: Applying the Value Stream Mapping to the 1x2 stone production process at the 350T/H stone crusher

GENERAL INTRODUCTION ABOUT DONG PHONG CO., LTD

Overview of Dong Phong Co., Ltd

- Company name: DONG PHONG CO., LTD

- Director: Ta Van Dong – Tax code: 3500689369

- Address: No 15A Ngo Duc Ke - Ward 7 - Vung Tau City

- Mail: dongphongvt@gmail.com.vn

Our business specializes in the extraction and production of various types of sand, gravel, and construction stone, along with leveling materials We also offer road and waterway transportation services, operate domestic ports, and engage in the construction of bridges, roads, and civil works Additionally, we provide commercial concrete and precast concrete structures to meet diverse construction needs.

The process of formation and development of Dong Phong Co., Ltd

Dong Phong Co., Ltd., founded on March 4, 2005, operates under business registration certificate No 4902000923 The company underwent its first expansion on April 13, 2009, followed by a second expansion on August 28, 2009 Additionally, on April 13, 2009, Dong Phong Co., Ltd updated its business code, receiving certificate number 3500689369.

Dong Phong Co., Ltd is a licensed enterprise engaged in various sectors, including the extraction of sand, gravel, and stone for road construction, as well as the collection of stones and ground filling for construction sites The company specializes in civil, industrial, and traffic construction projects, including electrical works up to 35 kV, dredging canals, and harbor construction Additionally, Dong Phong produces building materials and offers goods transportation services via inter-provincial and intra-provincial trucks and inland waterways The company also engages in the buying and selling of construction materials, petroleum, metal and electrical goods, construction iron and steel, and stationery, while providing maintenance and repair services for motor vehicles.

Although Dong Phong is a young company and has not been in the market for a long time, from the very beginning, leaders of Dong Phong Co., Ltd have consistently determined

The company's development strategy focuses on a human-centered approach and modern technology as core competencies, emphasizing growth in both breadth and depth To support this strategy, the company has invested in modern machinery and equipment while recruiting over 100 highly qualified staff members Annually, the company demonstrates its capabilities by excavating and transporting 3,000,000 tons of soil, supplying 700,000 tons of construction stone to the market, and providing loading, unloading, and warehousing services for 1,500,000 tons of goods at domestic ports Additionally, it constructs thousands of square meters of residential and infrastructure projects, and offers repair services for transportation means and construction machinery, along with mechanical product processing.

In a rapidly evolving market economy, Dong Phong Co., Ltd has swiftly adapted to integration trends to meet the growing demands of both domestic and foreign investors The company has actively engaged in numerous significant economic and political projects, demonstrating its commitment to excellence and innovation.

The Thi Vai SP-PSA International Port Project and its related initiatives, including the Cai Mep Thi Vai International Port Project and the CMIT, are pivotal developments in the region Notable projects such as the SITV International Port Project and the SP-SSA International Port Project enhance the area’s maritime infrastructure Additionally, the Duyen Hai thermal power plant and the Luong Song Hau sea dike project contribute to energy and coastal protection National Highway 51B and the KHANG LINH residential project area support regional connectivity and urban development The construction of the KM1810 to KM1816 section and the infrastructure of the MY XUAN B1 Industrial Park are crucial for industrial growth Investments in the Phu My III specialized industrial park and the expansion of the Formosa Nhon Trach factory further bolster the local economy The HALAVINA heavy industry factory project, KHANG LINH Vung Tau residential area project, Bao Toan Inland Port, and Long Son Refinery and Petrochemical Complex project are also significant contributors to the region's industrial landscape.

To enhance its competitiveness, Dong Phong Co., Ltd has established strategic partnerships with several enterprises, including Thanh Truc Company, Thuan An Co., Ltd., Phu Thai Co., Ltd., JSC VNDECO, and Construction Corporation No 1 (CC1) Through these collaborations, Dong Phong is now positioned to engage in bidding and the execution of project contracts valued at up to 1,000 billion VND.

1.2.1 Manufacturing capabilities of Dong Phong Co., Ltd

To meet the demands of large projects and evolving customer needs, Dong Phong Co., Ltd prioritizes the modernization of its equipment as a key strategy for enhancing competitiveness The company has invested in a robust fleet of over 100 motorized vehicles and machinery, boasting a combined capacity exceeding 20,000 horsepower, enabling it to handle substantial workloads while ensuring timely project completion Dong Phong Co., Ltd continues to strengthen and expand its fleet to maintain its operational efficiency and effectiveness.

Table 1 1: List of machinery and equipment for construction

No EQUIPMENT DISCRIPTION UNIT QUANTITY ORIGIN CAPACITY RESIDUAL

01 Ford Laser Unit 01 Viet Nam 80%

01 Wheel loader KOMATSU Unit 05 Japan 3-5T 80%

03 Static + vibrating roller 10 tons Unit 05 Korea 80%

04 Korean + Japanese excavator Unit 15 Korea 1,4T-3T 80%

06 Rock drilling machine type 2 rigs Unit 05 Japan 80%

07 Komatsu rock chisel Unit 05 Japan 80%

08 Hammer compactor Unit 20 Japan 2,2 HP 90%

09 Toad compactor Unit 10 Japan 3,5 HP 80%

10 Table compactor Unit 05 Japan 500-800kg 85%

11 Iron cutter Unit 03 Japan 5 HP 80%

12 Iron bending Unit 03 Japan 5 HP 80%

13 Iron straightening machine Unit 03 Viet Nam 1.5 HP 80%

(Source: Internal documents of Dong Phong Co., Ltd)

1.2.2 Management qualifications and professional qualifications

Dong Phong Co., Ltd believes that its workforce is the heart of its operations, viewing skilled human resources as a key competitive advantage The company prioritizes the development of its personnel in both quality and quantity, currently employing over 200 experienced staff members across various educational levels, from university graduates to intermediate professionals, who are engaged in roles ranging from management to operational positions.

Dong Phong Co., Ltd boasts a skilled team of professionals in Architecture, Construction, Mechanics, and Electrical-Electronics, enabling the company to effectively leverage advanced scientific and technical innovations This expertise enhances production and business operations, significantly boosting overall work efficiency.

19 Hoist winch Set 04 Viet Nam 10 HP 90%

22 Concrete batching plant Station 2 Viet Nam 60 T/h 95%

01 Power station 630KVA Set 02 Viet Nam 80%

03 Stone Crusher 350ton/hour Set 01 Japan 95%

06 Workshop for repairing and maintaining cars and machines m 2 2000

Main products of the Dong Phong Co., Ltd

Figure 1 1: Price list of the products of Dong Phong Co., Ltd

The main stones that the company produces include:

1x2 stone is the primary product of the company, serving as a crucial type of concrete stone for pouring fresh concrete or hot asphalt concrete This versatile material is essential in various construction applications, including road construction, high-rise buildings, wharf construction, and airport runways Accounting for approximately 85% to 90% of the dry volume of concrete, 1x2 stone significantly impacts the bearing capacity of concrete, making it a vital component in the construction industry.

Gravel, a stone material measuring 3-14mm, is a by-product of processing smaller stone sizes such as 1×1mm, 1×2mm, 2×3mm, and 4×6mm It is widely utilized in construction, serving as a base for cement bricks, floor tiles, and as an additive in concrete technology for pipe casting and various traffic infrastructure projects Additionally, gravel is essential in producing hot and cold asphalt, which can be applied directly to asphalt surfaces Its versatility extends to making block bricks, dash bricks, concrete woven sheets, and for leveling road and house floors in construction.

Dust gravel consists of stone particles smaller than 5mm, produced during the processing of stones such as 1 × 1 and 1 × 2 This material, also known as militia particles, is obtained through sieving with the smallest sieve Dust gravel is commonly utilized as a base for floor tiles, cement tiles, and as an additive in concrete technology for casting sewer pipes, as well as in various construction projects and other construction materials.

0x4 construction stone, commonly referred to as 0x4 stone, consists of small stones mixed with dust, measuring approximately 40mm (or 37.5mm) in size This high-grade construction material is produced by separating it from other stones, making it a preferred choice for various construction projects.

In construction, 11 stone is commonly utilized as a distribution stone for road pavement, serving to level, patch, and renew road surfaces Additionally, it plays a crucial role in leveling the foundations of houses and various auxiliary structures.

4×6 stone, measuring 40-60mm or 50-70mm, is a versatile construction material primarily used for foundation reinforcement, lining, and embankments Sourced through sieving from other stone products, this stone is essential in modern construction projects Typically, it is used alongside sand leveling and 0x4 stone, along with various other materials tailored to specific construction needs.

Organization structure of Dong Phong Co., Ltd

1.4 Organization structure of Dong Phong Co., Ltd

Figure 1 7: Organization structure of Dong Phong Co., Ltd

(Source:Internal documents of Dong Phong Co., Ltd)

The function of each position is demonstrated as follows:

The director is responsible for creating an organizational chart that outlines the activities at the quarry, while also planning both current and future strategies for each phase of stone mining and production Additionally, the director plays a crucial role in establishing and nurturing strong relationships with local authorities and stakeholders.

Work closely with related departments to achieve the company goals

+ Vice Director: Advise the Director on the construction, issuance and application of technical processes and regulations and directly direct and supervise the implementation

Manage all activities in the production process Organizing planning and making the most effective exploitation and production plan

The Construction Department is responsible for conducting blasting operations and transporting the resulting stones from the mountain to the quarry They oversee the management and efficient utilization of vehicles, equipment, and production lines for the extraction and processing of quarry products.

+ Design Department: Prepare equipment investment plans suitable to the scale of long- term development and demand in the market Develop and implement quarry development strategy, quarry product business strategy

The Production Department plays a crucial role in advising company leaders on technology and production-related issues while overseeing professional operations at the quarry It collaborates with the Board of Directors to effectively align with the company's development goals, develops plans to manage production volume and quality, and coordinates personnel on-site Additionally, the department ensures technical safety at the quarry and conducts maintenance on vehicles, machinery, and plants to optimize operational efficiency.

The Accounting and Materials Department is responsible for regularly and ad-hoc reporting on their assigned tasks as requested by management They meticulously record, collect, and invoice data related to the blasting, crushing, loading, and unloading processes of both raw materials and finished products.

+ Human Resources Department: Searching for talent, managing, and coordinating the staff to work effectively

+ Sales Department: Searching for customers, researching product development strategies Managing the company's sales.

Direction of activities in the future

- Constantly improve the output value and business results

- Invest in and renew modern technological lines

- Building in the direction of consolidating and expanding the staff, improving management skills, perfecting workers' skills to meet the most rigorous requirements of the investor

- Developing and expanding business lines while consolidating firmly position in participating markets

Business performance of Dong Phong Co., Ltd from 2018 to 2020

Table 1 2: Business performance report of Dong Phong Co., Ltd (2018 - 2020)

3 Net revenue from selling goods & providing services (01-02) 10 103,649,906,729 205,129,300,284 232,486,667,307

5 Gross profit on sales & service provision (10-11) 20 19,363,344,423 33,108,813,133 51,778,715,091

Based on the table 1.2, a column chart is drawn to show the company's profit after tax

The column chart is as follows:

Figure 1 8: Profit after tax chart of the company (2018 – 2020)

The chart clearly illustrates a significant surge in the company's profit after tax, which escalated from 4,603,532,286 VND in 2018 to 14,849,922,256 VND by the end of 2019, marking an impressive increase of approximately 300% By 2020, profits soared further, reaching 30,051,036,793 VND, reflecting a 200% rise compared to the previous year Additionally, in 2019, the company doubled its mining and production scale, showcasing its robust performance in stone production and a commitment to expanding its operational activities.

Chapter 2: Theoretical Basis 2.1 Lean Production Theory

2.1.1 What is Lean Production philosophy?

Lean manufacturing, first introduced by James Womack, Daniel Jones, and Daniel Roos in "The Machine that Changed the World," is a highly effective production method that enhances product quality while reducing costs This approach not only delivers a broader range of superior goods but also fosters more engaging and fulfilling work for employees at all organizational levels Consequently, the authors advocate for the global adoption of lean production practices.

Lean is a systematic approach to process improvement that focuses on identifying and reducing waste while fostering continuous improvement Originating from the Toyota Production System (TPS), Lean manufacturing emphasizes efficiency and effectiveness in operations.

Lean production, as defined by Womack and James (1996), focuses on the elimination of waste in the production process, identifying anything that does not contribute value to the final product as waste that must be removed The five core principles of Lean manufacturing include: clearly defining value for each product, identifying the value stream for specific product families, ensuring a smooth flow of value without interruptions, allowing customers to pull value from the manufacturer, and continuously striving for perfection.

The pull strategy, as outlined by Martins (2015), is an inventory management approach that emphasizes just-in-time delivery and reduces on-hand stock This method aligns production orders with actual downstream demand, eliminating the need for forecasts and ensuring that production is driven solely by current requirements.

3 Increased ability to adapt to variable demand

Figure 2 1: An example of a pull system

(Source: https://www.ineak.com/)

A Kanban system is always linked to this plan Kanban is a Japanese word that means

A Kanban system aims to ensure a steady flow of production materials (WIP) while minimizing inventory levels by facilitating the flow of information between customers and suppliers, thereby enabling the effective operation of the pull system.

Kanban cards come in two varieties:

Withdrawal Kanban serves as a notification system for transferring components between operations Each card is attached to components being transported to the necessary work area Once these components are utilized, the cards are returned as a signal to replenish the identical parts in the same quantity.

A production Kanban serves as a crucial tool in manufacturing, acting as a list of products required to meet customer demands It initiates the production of necessary parts, while a Withdrawal Kanban functions as a shopping list for material handlers, guiding them in retrieving and transferring components By activating the production process, a production Kanban provides essential information on the quantity of products to be manufactured, ensuring efficient workflow and inventory management.

According to Jeffrey K Liker (2004), achieving true success involves a continuous improvement process focused on identifying and eliminating waste This requires understanding the root causes of issues and implementing effective countermeasures Womack and James (1996) define "Muda," a Japanese term for waste, as any human activity that consumes resources without adding value to the product Examples of Muda include correcting mistakes, producing unwanted items that lead to excess inventory, unnecessary processing steps, inefficient employee movement, and delays caused by upstream activities not meeting deadlines, ultimately resulting in products that fail to satisfy customer demand.

Taiichi Ohno identified seven wastes in the Toyota Production System in 1988, which laid the foundation for Lean manufacturing As Lean principles expanded globally, an eighth waste—underutilized talent—was recognized, highlighting the importance of maximizing human resources To aid in recalling these wastes, a memorable abbreviation was developed.

"DOWNTIME." Was used (Jean Cunningham, 2020) The 8 waste includes:

Defects represent a significant form of non-value-added waste, as they lead to wasted time and labor on necessary corrections such as repairs, replacements, rework, and inspections, often resulting in additional costs from scrapped products Overproduction is another critical waste type, occurring when items are produced in quantities exceeding customer demand, making it the most detrimental waste type as it can trigger and exacerbate other forms of waste.

Waiting time is the duration a worker spends idle, awaiting resources like machines, tools, or supplies This non-value-adding time is often caused by bottlenecks, stock shortages, and delays in lot processing, which can hinder overall productivity.

Neglecting employee feedback can lead to a loss of valuable initiatives, skills, and improvements within a company This oversight not only diminishes employee engagement but also increases the risk of complacency and inattention, particularly when work becomes monotonous.

Transportation waste refers to the unnecessary movement of materials, products, or information, which negatively affects safety, lead time, quality, and cycle time Reducing this type of waste is crucial for improving overall efficiency and effectiveness in operations.

Excess inventory, including raw materials, work-in-progress, and finished goods, leads to increased lead times, higher storage costs, and risks of obsolescence and damage It also highlights underlying production inefficiencies, such as redundancies, flaws, excessive paperwork, downtime, and prolonged setup periods, ultimately hindering operational efficiency.

Theoretical Basis

Lean Production Theory

2.1.1 What is Lean Production philosophy?

Lean manufacturing, first introduced by James Womack, Daniel Jones, and Daniel Roos in "The Machine that Changed the World," is an effective production method that enhances product quality and variety while reducing costs This approach not only benefits consumers by delivering superior goods but also enriches the work experience for employees at all levels, from the factory floor to corporate headquarters The authors advocate for the global adoption of lean production to maximize these advantages.

Lean is a systematic approach to process improvement that focuses on identifying and eliminating waste while fostering continuous improvement Originating from the Toyota Production System (TPS), Lean manufacturing emphasizes efficiency and effectiveness in operations.

Lean production, as defined by Womack and James (1996), focuses on the elimination of waste within the production process, targeting anything that does not contribute value to the final product The five core principles of Lean manufacturing include: clearly defining the value of each product, identifying the value stream for specific product families, ensuring a smooth flow of value without interruptions, enabling customers to pull value from the manufacturer, and continually striving for perfection.

The pull strategy, as described by Martins (2015), is an inventory management approach that emphasizes just-in-time deliveries and minimizes on-hand stock In this system, production orders are driven by actual downstream demand rather than forecasts, ensuring that manufacturing aligns closely with real-time requirements.

3 Increased ability to adapt to variable demand

Figure 2 1: An example of a pull system

(Source: https://www.ineak.com/)

A Kanban system is always linked to this plan Kanban is a Japanese word that means

A Kanban system aims to ensure a seamless flow of production materials (Work In Progress) while minimizing stock levels by facilitating the flow of information between customers and suppliers, thereby enabling the effective operation of the pull system.

Kanban cards come in two varieties:

Withdrawal Kanban is a signaling system used to indicate when components need to be moved from one operation to another Each card is affixed to the components being transported to the necessary work area Once these components are utilized, the cards are returned as a signal to replenish the same parts in the same quantity.

A production Kanban is a crucial tool in manufacturing, serving as a list of products that must be produced to meet customer demands It initiates the production of parts, while a Withdrawal Kanban acts as a shopping list for material handlers, directing them to retrieve and transfer necessary components By triggering the production process, a production Kanban provides essential information on the quantity of products to be manufactured, ensuring efficient workflow and inventory management.

True success stems from a systematic improvement process aimed at identifying and eliminating waste, as highlighted by Jeffrey K Liker (2004) Understanding the root causes of issues and implementing effective countermeasures is essential for achieving success Womack and Jones (1996) define "Muda," a Japanese term for waste, as any activity that consumes resources without adding value to the product This includes correcting mistakes, producing unwanted items leading to excess inventory, unnecessary processing steps, inefficient employee movement, and delays caused by upstream activities that fail to meet customer demand.

Taiichi Ohno identified seven types of waste in the Toyota Production System in 1988 As Lean principles expanded globally, an eighth waste—underutilized talent—was recognized To aid in recalling these wastes, an abbreviation was created.

"DOWNTIME." Was used (Jean Cunningham, 2020) The 8 waste includes:

Defects represent a significant form of waste, as they result in the unnecessary expenditure of time and labor on correcting issues through repair, replacement, rework, and inspection, often leading to additional costs from scrapped products Overproduction is another critical waste, characterized by manufacturing items in excess of customer demand, which not only leads to inefficiencies but also creates opportunities for other types of waste to arise, making it one of the most detrimental forms of waste in any production process.

Waiting time is the duration a worker spends idle, awaiting the completion of tasks by machines, tools, or unavailable supplies This non-value-adding time is often caused by bottlenecks, stock shortages, and delays in lot processing, which can hinder productivity and efficiency.

Neglecting employee feedback can lead to a loss of valuable initiatives, skills, and improvements within a company This oversight results in disengaged employees, increased complacency, and a lack of attention, particularly when work becomes monotonous.

Transportation waste refers to the unnecessary movement of materials, products, or information, significantly affecting safety, lead time, quality, and cycle time Reducing this type of waste is crucial for improving operational efficiency and enhancing overall productivity.

Excess inventory, including raw materials, work-in-progress, and finished goods, leads to longer lead times and increased costs associated with storage, transportation, and damaged items It can also cause obsolescence and delays while masking production inefficiencies, redundancies, flaws, and extended setup times.

Motion waste encompasses any unnecessary movements made by individuals, equipment, or machinery, such as walking, lifting, reaching, bending, stretching, and moving Additionally, extra processing involves performing more work, incorporating additional components, or including more steps in a product or service than what the customer actually requires.

Figure 2 2: Eight types of waste

Lean manufacturing tools

To effectively address the eight types of waste in Lean manufacturing, a variety of specialized tools have been created to systematically identify and eliminate each waste category, promoting a culture of perfection and continuous improvement Below are several key Lean manufacturing tools designed for this purpose.

5S is about eliminating non-value-added activities by establishing standard techniques for performing the required tasks As a result, a good 5S program boosts productivity, quality,

20 workflow, and staff safety (David Visco, 2016) 5S is derived from Japanese terms beginning with the letter "S" In which:

1S – Seiri (Sort): The goal is to categorize all superfluous objects and separate those that are not used on a daily basis (Filip & Marascu-Klein 2015)

2S – Seiton (Straighten): The principle is to establish a single storage space for all goods inside the work area (Ramdass 2015)

3S – Seiso (Shine): This entails cleaning the entire workplace, including the equipment, to ensure the best hygiene and safety conditions (Filip & Marascu-Klein 2015)

Seiketsu, or Standardize, is the initial step in maintaining the first three S's in an operational framework The objective is to create standardized procedures that enable operators to perform their daily tasks consistently and efficiently, ensuring a streamlined workflow across the organization (HungLin 2011).

5S – Shitsuke (Sustain): The first three stages are operational; the fourth phase keeps the preceding phase's state, and the fifth phase creates a commitment to continuous improvement (Mariano et al 2015)

In "Learning to See" by Mike Rother and John Shook (1999), Value Stream Mapping (VSM) is introduced as a visual tool that enables users to visualize and analyze their processes, helping to identify waste and improve efficiency.

The Value Stream Mapping (VSM) technique enables users to visualize the flow of materials and information throughout the value stream of a product By creating a detailed blueprint, it becomes easier to implement lean principles, which helps in identifying and eliminating waste and its sources within the process.

Figure 2 4: An example of a VSM

2.2.2.1 Steps to draw a Value Stream Map

Before creating a value stream map (VSM), it's essential to select a product family, which consists of products sharing similar processing steps and equipment (Rother and Shook, 1999) Since value streams often involve multiple product families, it is impractical to develop a VSM for each individual product Instead, identifying product groups with higher demand allows for a more efficient approach Concentrating on a product family that delivers significant value to customers ultimately benefits the user more effectively.

Figure 2 5: Steps to implement a VSM

To effectively analyze the value stream, it is essential to visit the plant or shop floor for direct observation and mapping of the current processes Start by walking along the value stream to understand the flow and order of operations while engaging with operators to gather insights Pay attention to both material and information flow, and ensure that process box data is filled out with lean metrics, including process cycle time, changeover time, yield, and machine uptime Additionally, create a timeline that incorporates processing and inventory waiting times to assess production lead time, as well as value-adding and non-value-adding times According to Rylander and Axelson (2013), a method utilizing video recording can effectively gather time data for analysis within a limited timeframe This approach involves identifying key process activities and capturing them with a synchronized camera to provide a comprehensive overview of production activities, ensuring that loading and unloading processes are accurately recorded within the same cycles for precise measurement.

Figure 2 6: Developed method process steps

The activities in the process are quantified through video analysis, where the duration of each activity in every cycle is recorded This data is aggregated to calculate an average value for the Value Stream Map (VSM) The VSM serves as a tool to assess the current operational efficiency, helping to identify bottlenecks and waste within the process For a visual reference, the VSM icons can be found in Appendix A.

After creating the current state map, it's essential to assess the value stream for opportunities to enhance flow by eliminating waste The next step involves designing the future state Value Stream Map (VSM), representing the ideal scenario post-lean implementation, focusing on minimizing waste within the value stream.

(2002), Several Lean guidelines that are useful to support the user to develop the future state of VSM are as the following:

Production based on Takt time

Takt time serves as the essential rhythm of a Lean system, dictating the speed at which products must be manufactured to satisfy customer demand It is determined by dividing the rate of customer demand per shift (in units) by the available working time for that shift This calculation is crucial for optimizing production efficiency and aligning manufacturing processes with customer needs (Rother and Shook, 1999).

Takt time = The customer demand rate (in units)

The available working time (per shift)

Develop continuous flow whenever possible

Continuous flow manufacturing, as defined by Rother and Shook (1999), involves producing one item at a time, ensuring that each piece moves smoothly to the next stage without delays or waste This one-piece flow approach enables businesses to reduce work-in-progress, minimize interruptions, shorten lead times, and decrease waiting times, all while enhancing overall quality and flexibility.

Site Visualization Site capture Site capture analyze

According to Rother and Shook (1999), the supermarket pull system exemplifies an effective inventory management method where finished goods are held until customer orders are received When an order is placed, items are taken from the inventory, prompting upstream systems to replenish the supermarket with an equal quantity of goods, thereby maintaining stock levels efficiently.

Figure 2 7: An example of a supermarket pull system

(Source: Rother and Shook, 1999) FIFO (First In First Out) lane

In a pull-system supermarket, maintaining a comprehensive inventory of all part variations is often impractical due to space constraints To address this, a FIFO (First In, First Out) lane can be implemented between two operations, effectively replacing a traditional supermarket and ensuring a smooth workflow This FIFO lane functions like a chute with limited inventory capacity, where the supplier process feeds into the entry and the customer process takes from the exit When the FIFO lane reaches its capacity, the supplying operation must pause until the customer utilizes some of the inventory (Rother and Shook, 1999).

The pacemaker is the point at which the work is scheduled This pacemaker process will determine how fast the value stream should operate (Rother and Shook, 1999)

Figure 2 8: An example of a pacemaker process

(Source: Rother and Shook, 1999) Load levelling

Leveling the product mix involves evenly distributing the production of different products over time By optimizing the product mix at the pacemaker process, businesses can enhance their responsiveness to diverse customer demands while maintaining low finished goods inventory levels.

The frequency of work release or removal from the pacemaker is often determined by the pack-out container quantity, which refers to the number of parts in a finished-goods container For example, if the takt time is 30 seconds and the pack size is 20, the pitch time would be 10 minutes (calculated as 30 seconds multiplied by 20 parts) This means that every 10 minutes, the pacemaker process should be commanded to generate one pack quantity while simultaneously removing the finished pitch amount.

Once the future state value stream map is created, it serves as a foundation for developing an effective implementation strategy aimed at achieving the desired ideal state This strategy should encompass specific improvement actions and a timeline for monitoring progress Following the completion of all operations, users can continue to enhance the value stream by iterating through this cycle of improvement.

26 of building the current state VSM, assessing, mapping the future state, and implementing improvement

THE ACTUAL SITUATION OF THE STONE CRUSHING PROCESS AT 350T/H STONE CRUSHER AT DONG PHONG CO., LTD

Introduction of 3A quarry Dong Phong Co., Ltd

Figure 3 1: An overview image of 3A quarry

The 3A quarry, operated by Dong Phong Co., Ltd since 2014, is situated at Ong Cau Mountain in Chau Pha commune, Ba Ria - Vung Tau province This open-pit quarry primarily extracts minerals near the surface, with stones being the predominant resource The extraction process involves blasting and drilling, targeting stone outcrops in the hillside According to company records, the quarry has an estimated annual production capacity of approximately 700,000 tons of stone, based on the allowable monthly production limits outlined in its licenses.

Table 3 1: The production of Dong Phong Co., Ltd

In 2020, the 3A quarry produced and consumed a total of 350,330.54 tons of 0x4 stone, making it the most dominant aggregate Additionally, the quarry extracted a significant amount of 1x2 stone, totaling 276,844.53 tons for the same year.

In 2020, the company exploited 456,190.62 T stone, lower than the regulations of the license (700,000 T) Therefore, the company is planning to expand the scale of stone mining and production

Introduction of the stone production process at the 350T/H stone

crusher of Dong Phong Co., Ltd

Figure 3 2: Stone mining and production process at 3A quarry

The initial step before blasting involves stone drilling, where construction workers create holes of specific dimensions to accommodate explosives A meticulously planned drilling pattern outlines the necessary spacing, burden, hole depth, diameter, and quantity of holes, ensuring adherence to the established guidelines Currently, the company employs manual drilling techniques, utilizing a pneumatic hand-held drill to prepare the holes for the subsequent blasting operation.

After drilling, the quarry's blasting team employs the Open Cast Bench Blasting method for multi-bore blasting, utilizing a bench system to ensure safe working conditions The process involves using an electric starter system with slow detonators and ANFO (Ammonium-Nitrate mixed with fuel oil) as the primary explosive Before detonation, the team connects the circuit in series and verifies connections with an Ohm meter to ensure all holes are properly linked and secure.

Drilling Blasting Mucking and scaling Breaking

The explosion is initiated with dynamite, ensuring safety by keeping all workers, machinery, and vehicles at a safe distance from the blasting site to avoid fly rock incidents Additionally, operations at nearby crushing plants will be halted during the blasting to maintain safety protocols.

The blasting process will be conducted to efficiently break rock from the bench, with any remaining rock being removed by excavators Simultaneously, unstable rock pieces will be scaled or removed using either excavators or manual labor as needed The blasted rock that falls to the quarry floor will be sorted into larger boulders, which will be prepared for crushing by the excavators during the mucking process Any boulders exceeding the maximum feed size for the crushing plant will be further reduced in size using a hydraulic rock breaker attached to an excavator.

Blasted stones from the quarry are loaded into dump trucks by excavators, which then transport the material either to the crushing plant or directly to customers.

32 necessary A full fleet of trucks will be used for this purpose to ensure a constant supply of blasted stones

Figure 3 4: An excavator is loading blasting stones for a dump truck

At the inlet weighing station, dump trucks are weighed before transporting blasted stones to the crusher hopper, ensuring proper tonnage control to prevent overloading that could cause delays in the crushing process This station also serves as a data collection point for the production department, where records are stored, transactions are processed, and analysis of stone volume and vehicle count is conducted, providing valuable insights for quarry management on production efficiency.

3.2.5 Stone crushing process at the 350T/H stone crusher in quarry 3A site

Figure 3 5: The stone crushing process at 350T/H crusher

Blasted stones are transported from the quarry to the crusher hopper via truck Once in the hopper, the rocks are fed through a vibrating feeder and onto a belt conveyor, leading to the primary jaw crusher for processing.

A jaw crusher operates by compressing and crushing rock between a movable jaw and a fixed jaw As the rock is loaded from the top, it is broken into smaller pieces through the back-and-forth motion of the movable jaw Crushed stones exit the machine from the bottom, with the size of the output determined by the gap between the jaws The jaw crusher is designed to handle blasted stones ranging from 0 to 80 cm, with an adjustable outlet size between 20 mm and 165 mm, ensuring efficient operation and preventing jamming from oversized materials.

The vibrating screen is a crucial component in the stone processing workflow, where stones are conveyed via a conveyor belt after being crushed by a primary jaw crusher It features a three-layer design that filters stones through varying pore sizes to separate them by size The operation is driven by a motor connected to the screen box shaft through three V-belts, with the screen box supported by springs and mounted on an inclined frame at an angle of 15° to 30° Depending on the specific model, the vibrating screen can classify materials into 3 to 5 different categories simultaneously.

The secondary crusher processes semi-finished stones, which are conveyed from the vibrating screen It operates similarly to the primary jaw crusher, reducing stone size to smaller fragments ranging from 0 to 60mm.

The cone crusher plays a crucial role in the stone crushing process by further reducing the size of stones that have already been processed by a secondary jaw crusher After being transported via a belt conveyor to a storage tank, the stones are then fed into the cone crusher, where they are broken down from 0-60mm pieces This is achieved through a pressing mechanism between two rotating cones, which crush the stones as they enter Larger stones are initially broken, and the resulting fragments undergo additional crushing until they are small enough to pass through a narrow opening at the bottom of the cone crusher, allowing for seamless transfer to the next stage of processing.

Crushed stones are transported via a conveyor to a vibrating screen, which operates similarly to the conveyor but features smaller sieve holes for classifying finer stones Once the stones pass through the vibrating screen, they are stored in a Silo, which serves to maintain a continuous supply for the subsequent two cone crushers.

- The next-stage cone crusher: At the next stage, stones from the Silo are transferred to

2 cone crushers by a belt conveyor Here, stones are further crushed by the two cone crushers

38 and rounded with the purpose of increasing the quality and aesthetics of stones, reduce the flakiness index and help increase the compressive resistance of concrete products

After being processed by two cone crushers, stones are conveyed via a belt conveyor to a vibrating screen for sorting into final products These products include various sizes such as 1x2, 5x19, 4x6, as well as gravel, dust gravel, concrete, and mortar, tailored to production requirements The finished products are then stored in separate stockpiles by size until they are sold or utilized.

Figure 3 13: Stockpiles of finished products

3.2.6 The process of storing and loading customers at 3A quarry

Figure 3 14: Storing finished stone product process in the quarry

In the process of managing finished stone products, belt conveyors separate stockpiles for efficient distribution Depending on customer needs, two wheel loaders are designated to load these products onto trucks, which are then weighed at the output station before transporting the stones to various consumption sites, including agencies, road development projects, and the construction industry To optimize space in the production area and prevent excess stockpiling, the wheel loaders also shovel stones onto the trucks, which subsequently deliver the finished products to immediate storage until needed.

Advantages and disadvantages of the 350T/H capacity stone production process at 3A quarry

During the internship at the company, the author has recorded the strengths of the stone production process at the company’s current 350T/H stone crusher:

The company boasts a state-of-the-art 350T/H capacity stone crusher, imported from Japan, designed for efficient crushing of various rock types, including limestone, basalt, granite, cobblestone, and coal This fully automatic crusher features a user-friendly design, eliminating the need for installation prior to operation.

The stone crusher is designed for easy operation, allowing users to start crushing with the press of a button Its simple design ensures convenient maintenance, while its flexible configuration offers a large crushing ratio, high production efficiency, and substantial processing capacity Constructed with high-strength, wear-resistant materials, the machine boasts minimal wear and a long service life, providing significant economic benefits The crusher produces high-quality stone products with low clay content and impressive bulk densities Additionally, the company utilizes an advanced electronic weighing station to monitor stone input, preventing overloads that could disrupt production This system effectively identifies errors, ensuring smooth operations Furthermore, the investment in a fleet of modern production vehicles enhances the company's construction capabilities.

Figure 3 15: Some of the vehicles and machines of Dong Phong Co., Ltd

The proximity of the stone crusher to the quarry significantly minimizes transportation time and costs associated with moving stone from the blasting site to the crusher hopper An efficiently designed truck path further reduces waste by eliminating unnecessary transport Additionally, experienced truck drivers, equipped with excellent driving skills and situational awareness, ensure safe and accident-free transportation.

The manager closely monitors daily production activities at the mine, ensuring direct oversight of operations at the quarry The company employs one supervisor for quarrying and another for crushing, both of whom are experienced in quality control and hold degrees from the University of Mining and Geology Their extensive experience in checking sample sizes, grading, and effectively setting up the stone crusher enables the company to maintain top-quality stone products Additionally, the mine workers demonstrate a strong sense of responsibility by proactively cleaning and sanitizing the crusher 30 minutes before the morning shift, which enhances machine efficiency.

While there are several advantages to the stone production process at Dong Phong Co., Ltd, it is important to acknowledge the significant drawbacks that currently impede the company's growth and require improvement.

Overproduction waste is a significant drawback in the stone production process, primarily due to the company's lack of a specific production plan Relying on estimates from the quarry manager, the current strategy focuses on maximizing output, leading to excessive stone production This results in large piles of stone that obstruct truck transportation, create traffic jams, and pose safety risks for drivers and workers Furthermore, these accumulations hinder the company's ability to expand production, as they occupy valuable space needed for new machinery Additionally, the limited size of the crushing area necessitates double handling and intermediate storage of excess material, complicating operations further.

When customers request large quantities of stone, it may necessitate clearing out remaining products from the crushing site to create sufficient space for production, located approximately 250 meters from the crusher plant This process requires additional wheel loaders and dump trucks to transport materials to an intermediate warehouse, leading to unnecessary transportation and increased waste.

One significant disadvantage in the quarrying industry is the frequent breakdown of machinery, which can severely disrupt operations On certain days, multiple excavators may be out of service, necessitating reliance on excess production from crushers to maintain workflow The specialized nature of mining equipment often results in prolonged downtimes, with some stone crusher machines remaining unrepaired for months due to unavailable parts To mitigate the impact of these breakdowns, companies typically maintain excess production; however, this approach is merely a temporary fix Over time, the excessive use of machinery during breakdowns can reduce their lifespan and lead to even more frequent failures, highlighting the need for a more sustainable solution.

The company is facing significant challenges due to the inefficiency of its Maintenance Department The lack of awareness among repair and maintenance workers, coupled with a disorganized workshop, hampers their ability to locate necessary tools and equipment swiftly This disarray results in excessive movements and delays in maintenance tasks, ultimately impacting production activities Furthermore, the presence of obsolete and unused items occupies valuable workshop space, preventing the installation of new equipment essential for effective maintenance work.

The weakness of the maintenance department also leads to the lack of machinery for production The breakdown of excavators, breakers and dump trucks were not timely, so some

Delays in subsequent processing stages at the construction site, including breaking, loading, transporting, and handling, ranged from 2 to 4 hours on certain days A significant disruption occurred when a stone crusher plant broke down, halting quarry operations for several days and preventing production Additionally, machine maintenance is time-consuming; excavators and mowers require regular servicing every 250, 500, and 1000 hours, with 250-hour and 500-hour services taking approximately 2 hours each, while a complete 1000-hour service requires about 5 hours.

The stone crushing process is significantly impacted by maintenance and breakdowns, leading to delays in operations Regular maintenance of machines and vehicles is essential, but it can be time-consuming, contributing to slowdowns in the overall process Consequently, the efficiency of stone crushing activities is adversely affected, highlighting the importance of timely maintenance to minimize disruptions.

Dong Phong company is facing significant environmental challenges due to its mining operations, which are contributing to widespread ecological damage The maintenance and cleanliness of the crusher site are inadequate, highlighting a lack of effective sanitation management As a result, the quarry site is littered with broken machinery and waste materials, including hydraulic and engine oils, vehicle parts, and discarded containers, which further exacerbates the environmental impact.

Figure 3 16: Poor appearance of the maintenance workshop at quarry 3A

The company has initiated limited actions to address air pollution at the 3A quarry site; however, these measures are insufficient to effectively manage dust generated during stone crushing and screening processes Significant dust particles can travel considerable distances, particularly during jaw crushing, cone crushing, vibrating screening, and on output conveyors Table 3.2 below presents the measured concentrations of suspended dust at key locations within the crushing and screening area.

Table 3 2: The concentration of suspended dust at stone crushing plant

TT Activity Concentration of dust (mg/T)

5 Finished product output of belt conveyor

Notes: 1 When there is a dump truck; 2 2 - 3m away from the location where dust is generated; 3 15 - 20m from the crushing and screening system

(Source: from document of Dong Phong Co., Ltd)

Dust samples from the stone processing area of the 3A quarry reveal that particles sized between 3.3 and 10 mm constitute the majority of respiratory dust This type of dust poses significant environmental pollution risks and adversely affects employee health, highlighting the urgent need for effective dust management strategies.

Operating in hazardous conditions, the company’s management system has neglected to prioritize worker health, resulting in unsafe work environments At the 3A quarry, the process of crushing construction stone produces significant dust, particularly fine particles, which pose serious health risks These dust emissions can lead to respiratory diseases among workers in the mining sector.

APPLYING THE LEAN TOOLS TO THE 1x2 STONE PRODUCTION

The Value Stream Mapping tool

4.1.1 Purpose of using the value stream mapping tool (VSM)

The stone production process at the company faces several negative aspects, including overproduction, waiting, unnecessary transportation, lack of standardization, safety issues, and pollution To address these inefficiencies, developing a value stream mapping (VSM) is essential VSM serves as a powerful tool for identifying and eliminating waste within the stone manufacturing process by allowing managers to visualize the entire workflow It illustrates the flow of products from start to finish and highlights the connection between information and material flow Additionally, VSM enables managers to recognize sources of waste, making it easier to make informed decisions and tackle inefficiencies effectively.

The author suggests creating a value stream map (VSM) for the stone production process at the 3A quarry site to identify waste and non-value-added activities By doing so, the aim is to propose solutions that eliminate these inefficiencies, ultimately enhancing productivity and better meeting customer demands.

4.1.2 Developing a Value Stream Mapping of the 350T/H stone production process 4.1.2.1 Choosing the main product family to draw the Current State Value Stream Map (CSVSM)

The company currently manufactures a variety of distinctive stone products, including 1x2 stone, 0x4 stone, 4x6 stone, gravel, and 5x19 stone For the purpose of analyzing production efficiency, the author focuses on the high-volume products that represent the majority of total stone output to create a value stream map As illustrated in Figure 4.1, the Pareto chart highlights the company's order volume for stone product families over a three-year period from 2018 to 2020 According to Pareto's principle, 80% of the company's revenue is generated from just 20% of its products, emphasizing the significance of identifying key items in the production lineup.

The steepest part of the curve, where the slope begins to flatten, is crucial for understanding the significance of various materials, including 1x2 stone, gravel, and processed gravel products For Dong Phong company, integrating these key principles is essential for optimizing their operations and product offerings.

The Pareto chart highlights that the 1x2 stone, gravel, and 0x4 (processed) product families are the primary focus for the company, representing 41.42%, 22.3%, and 21.2% of total stone production, respectively Consequently, this research will concentrate on these key product families to optimize production strategies.

0x4 (processed) lines and select these product families to draw the current-state map

Table 4 1: Consumption of the stone product

No Target Unit Consumed quantity

Figure 4 1: Pareto Chart of Stone quantity consumed (2018-2020)

To have an overview of the process producing 1x2 stone, the author creates a SIPOC diagram of these product families

Supplier Input Process Output Customer

Blasted stone Stone crusher 350T/H plant Operators Vehicles Machines

Agencies Construction areas Road construction

Figure 4 2: SIPOC diagram of the 1x2 stone, gravel, 0x4 (processed) stone families

Ong Cau Mountain serves as the primary supplier of raw materials for the 1x2 stone, gravel, and 0x4 processed stone crushing operations The process begins with blasting and rock breaking, followed by mucking and scaling, which allows for the extraction of blasted stone that is then transported to the stone crushing facility.

The stone crushing manufacturing process primarily relies on blasted stone sourced from Ong Cau Mountain, utilizing a fleet of vehicles including dump trucks, wheel loaders, excavators, and hydraulic machines The stone crushing plant is equipped with essential components such as a hopper, vibrating feeder, primary and secondary jaw crushers, a cone crusher, belt conveyor, vibrating screen, and dynamo, all operated by skilled workers.

Loading Transport Feeding the crusher Crushing Loading

- Process: The table 4.2 below shows activities in the stone crushing process:

Table 4 2: Activity in the stone manufacturing process

Loading An excavator loads blasted stones onto a dump truck

Transporting and feeding the crusher A dump truck transports blasted stone to the stone crushing hopper and feed blasted stones into the hopper

Crushing Blasted stone turn to finished products after going through a crushing process includes hopper, vibrating feeder, primary jaw crusher, secondary jaw crusher, cone crusher, belt conveyor, vibrating screen

Loading customers A dump truck is loaded by a wheel loader and then deliver finished products to customers

- Output: Output of the stone production process is the 1x2 stone, gravel, 0x4 (processed) stone

- Customer: The main customers of the company are construction projects such as road, harbor, infrastructure construction Besides, the company also provides stones to several retail construction agencies

To create an effective value stream mapping (VSM) for the company’s stone quarry, it is essential to observe all production activities at the 350T/H crusher over a two-month period During this time, critical data such as cycle time, the number of operators, and waiting times for each process will be meticulously collected through direct measurements and information from relevant departments This data will serve as the foundation for analyzing the VSM at the company’s 3A quarry, ensuring a comprehensive understanding of the production flow and efficiency.

Cycle time, lead time, and various types of time—including Value-Added time and Non-Value-Added time (NVA)—are crucial metrics in process analysis Cycle time refers to the duration from the beginning to the end of a process and is calculated using the time study method, where each activity's cycle time is measured five times with a stopwatch and recorded in a time study worksheet For Non-Value-Added time, the author measures waiting times for each activity 20 times, utilizing a stopwatch for accuracy The collected data is then analyzed using SPSS to enhance the current state map and line balance chart, as detailed in Appendix B.

This article discusses the use of 25 statistical software tools (refer to Appendix B) to create histogram charts that illustrate frequency distributions The mean cycle time values derived from these histograms will be incorporated into a map, serving as a database for evaluating and analyzing process waste Additionally, the article highlights lead time as a key metric, representing the total time taken from the beginning to the end of a process.

4.1.2.3 The Current State Value Stream Map (CSVSM)

The author creates a current state value stream map to visually depict the product and information flow in the stone production process at the 350T/H crusher By analyzing this data, the author identifies non-value-added activities that can be minimized or eliminated to enhance efficiency Utilizing a Yamazumi chart, the analysis pinpoints bottleneck cycle times and compares them to takt time, assessing whether the process is over capacity Additionally, the author calculates production time based on the current state map to identify wasteful activities and predict the benefits of implementing lean production tools This current state map serves as a foundation for improving the stone production process.

52 Figure 4 3: Stone production Current State Map at 350T/H stone crusher

Customer Demand 871.6 T/day (Takt Time 602 sec/20 T

Upon receiving customer orders, the production department at Dong Phong Co., Ltd initiates quarry blasting within three days, followed by production In 2021, the demand for stone products, including 1x2 stone, gravel, and processed 0x4 stone, reached 257,121.35 tons, translating to a daily requirement of 871.6 tons The takt time for production is calculated at 602 seconds per 20 tons, as detailed in the accompanying table.

Table 4 3: Takt time of the stone production process

Takt time = Net available time per day

The author selects the unit of 20 tons (20T) as it represents the average volume of stone equivalent to one dump truck Takt time is determined by dividing the available production time of 34,200 seconds by the daily requirement of 871.6 tons of 1x2 stone Each production shift lasts 12 hours, which includes a 1-hour lunch break (7,200 seconds) and 30 minutes (1,800 seconds) allocated for cleaning the crusher before plant operations commence.

Table 4 4: Activities in the production process

After the mining operation, excavators stock blasted stones at B1, where a dedicated excavator and dump truck transport the stones to the 350T/H crusher hopper Following an electronic weighing process, dump trucks carry approximately 20T of stone materials to the crushing plant The loading time for each excavator cycle is 590.43 seconds, which includes 264.3 seconds of waiting time as it loads blasted stone into two additional dump trucks for other crushers.

Blasted stones are transported to a 350T/H crusher hopper, where they are fed into the hopper within 273.4 seconds per cycle to initiate the crushing process The crusher then processes the stones, averaging 20 tons every 300 seconds per cycle Once crushed, the finished products are transferred to stockpiles via a conveyor outlet When customer demand arises, a wheel loader is dispatched to load stones onto dump trucks for delivery If stockpile B2 is full, the wheel loader moves stones to intermediate storage B2*, located approximately 250 meters away, with each cycle taking 256.65 seconds, which includes 117.81 seconds of waiting time Observations indicate that the inventory time for finished products is managed efficiently.

Implementing 5S project in the maintenance department

The primary challenge facing the company in its stone production process is the inefficiency of the maintenance department To address this issue effectively, it is crucial to identify the root causes of the waste generated Utilizing a Fishbone diagram allows for a comprehensive analysis of the problem, enabling the company to pinpoint the underlying issues and develop optimal solutions for improvement.

Figure 4 10: Fishbone diagram of the problem in maintenance store of the company

Table 4 5: Proposed solutions for the maintenance department

The author proposes several solutions to address the current issues in the maintenance department, as illustrated in the fishbone diagram (Figure 4.9) and detailed in the accompanying table Each solution aligns with the stages of the 5S project, making them suitable for implementation For example, the Sort stage (1S) focuses on eliminating unnecessary items from storage, while the Set-in-order stage (2S) emphasizes optimizing layout and organization The Shine stage (3S) offers strategies for maintaining cleanliness and scheduling cleaning tasks Consequently, the author recommends the adoption of a 5S project to enhance the overall performance of the maintenance department.

Number Problems Identified Proposed Solutions

1 Unnecessary, useless, and out-of-date tools

Apply the RED TAG method in the maintenance store

2 Inappropriate workbenches Improve workbenches layout

3 Rather disorganized Development of a new layout

4 Tools scattered across the workspace Create a Tool Shadow board (board for hanging up tools) in the store

5 Unorganized facilities in the store Re-layout the facilities

6 Personal protection equipment (PPE) hanging on the workbench

Provision of lockers for PPE

7 Disorder of auxiliary tools Provision of a tool trolley

8 Cement floor (absorbs liquids) Use the floor that avoids liquid absorption

9 No cleaning tools in the store Provide cleaning tools in the store

10 No cleaning schedule Create a cleaning schedule

4.2.2 Implementing the 5S project in the maintenance department of the company

Project objective: Applying 5S methodology in the maintenance department of Dong

Phong limited company to eliminate waste, increase the capability of the maintenance store to eliminate the problem of lacking machinery for the stone production operation

Project scope: Maintenance workspace of the company

Project team: The 5S project team includes:

Responsible for setting the limit for the project, the mindset of 5S and approving decision of the 5S project

Responsible for the success of the 5S project and the project team Planning the project, provide guidance for project members and work with them

Work under the project manager, involve in the implementation of the 5S project, bring opinions from other maintenance employees

The expectation of the author after closing the 5S project is:

Eliminating unnecessary items will create additional free space and improve storage in the maintenance store, allowing for better organization of tools and IPE This streamlined approach minimizes waste materials, labor, and time, enhancing overall efficiency.

Enhancing the layout organization allows employees to locate tools more quickly, reducing errors in tool selection and minimizing the risk of misplacing them As a result, tools and machines are consistently well-prepared and readily available for use.

Enhancing cleaning efficiency not only minimizes the need for fire-fighting measures in the store but also improves visual clarity, allowing for the early identification and resolution of potential issues before they escalate This proactive approach fosters a safer shopping environment by eliminating sources of workplace accidents and near-misses Additionally, it contributes to an overall improvement in the work environment and elevates the company's maintenance standards.

Before sorting can take place, it is essential to first categorize all items at the quarry site, including materials, equipment, tools, documents, and records The sorting process involves classifying various elements such as vehicles and machines, as illustrated in figure 4.11 below.

Figure 4 12: Categorizing machines, vehicles, tools, parts chart

Machines, tools, and parts are categorized into two main groups: (1) those that cannot be utilized or are unspecified, and (2) those that can be utilized The first group consists of defective, damaged, or outdated equipment, which must be eliminated The second group is further divided based on the frequency of use.

Rarely used: include special machines, parts and tools are used only once or twice a year they should be stored in a separate area, near where they will be use

Occasionally: Items are being used at least once every 1 or 2 months It is best to keep them near the area/step where they will be used

Frequently used is used with daily or weekly frequency They are kept in the work

Store near the use area

Store near the operation area

Frequencies of use Description Action

70 area, even within reach if the item is used daily or hourly

With the purpose to conduct the first S successfully, the author recommends the company follow strictly to the process flow chart below:

Figure 4 13: Recommended Process Flow Chart for 1S Stage (Sort)

(Source: Jiménez, Romero, Domínguez and Espinosa, 2015)

The recommendation of the 1S stage is:

To ensure a well-organized workplace, the company must categorize all items appropriately and identify obsolete or infrequently used materials for elimination Additionally, it is essential that all chemicals are clearly labeled with relevant information.

It is not known No

All items must be stored in clearly labeled containers, including their expiration dates and usage instructions Nothing should be placed on top of shelves, file cabinets, or lockers The company should implement a red tag schedule that outlines the procedures for tagging items, ensuring that red tags are readily available in the designated area Additionally, a specific area for placing red-tagged items must be clearly identified and communicated.

During this phase, it is essential for the company to capture before and after images to effectively showcase the changes resulting from the project This practice enables the company to monitor progress and assess whether they are on the right path to achieving their goals.

To optimize workspace efficiency, tools and fixtures that are used infrequently should be stored away from the immediate work area It is essential for companies to standardize the tools required for tasks, ensuring that all employees utilize the same equipment This eliminates the necessity for personal tools or individual toolboxes, promoting consistency and organization in the workplace.

Every team member understands their roles and responsibilities in the 5S process, ensuring active participation in daily, weekly, and monthly 5S activities Additionally, each department should take part in regular audits to maintain and enhance the effectiveness of the 5S initiatives.

Stage 2: The 2S stage (Set in order)

The initial phase focuses on repurposing existing structures in the maintenance store while investing in new support facilities to enhance efficiency and reduce costs A more efficient workbench for maintenance and the implementation of a Shadow board streamline operations, allowing operators to quickly access tools and lifting accessories These enhancements not only minimize errors but also significantly accelerate the process of selecting the right tools.

The "Set in Order" stage involves organizing necessary items in logical, convenient, and safe locations for easy access The core principle of this stage is that every object should have its designated position To ensure proper placement, consistently ask yourself if the item's location is correct and how you can verify its accuracy If it’s not in the right spot, determine the correct location for it Implementing the "Set in Order" step effectively is crucial for maintaining an orderly environment.

Step 1: Replace the current cement floor with a new floor that avoids liquid absorption: Presently, the work floor of the maintenance department is made of cement which makes

The cement floor complicates cleaning tasks and obscures potential risks, which can lead to severe damage if not addressed promptly To mitigate these issues, it is recommended that the company replace the current flooring with a liquid-resistant option, such as by applying liquid-resistant paint This upgrade will simplify cleaning for staff and enhance the visibility of potential problems, allowing for more efficient identification and resolution.

Tiêu đề	Applying Lean Tools To Identify And Eliminate Waste In The Stone Production Process At 350T/H Stone Crusher At Dong Phong Co., Ltd.
Tác giả	Nguyen Ngoc Toan
Người hướng dẫn	M.E Nguyen Thi Mai Tram
Trường học	Ho Chi Minh City University of Technology and Education
Chuyên ngành	Industrial Management
Thể loại	graduation dissertation
Năm xuất bản	2022
Thành phố	Ho Chi Minh City

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