In this chapter, the following content will be discussed: Variables and attributes, control charts for variables, parameters, control charts for attributes, tolerances, process capability, understanding continuous improvement, deming 14 points, TQM, seven quality tools, maintenance and reliability, reliability, product failure rate, providing redundancy, maintenance cost, total productive maintenance.
LECTURE 30 LSM733-PRODUCTION OPERATIONS MANAGEMENT By: OSMAN BIN SAIF Summary of last Session CHAPTER : CAPACITY AND CONSTRAINT MANAGEMENT u Capacity u u u u u Design and Effective Capacity Capacity and Strategy Capacity Considerations Managing Demand Demand and Capacity Management in the Service Sector u Summary of last Session(Contd.) Bottleneck Analysis and Theory of Constraints u u u u Process Times for Stations, Systems, and Cycles Theory of Constraints Bottleneck Management Break-Even Analysis u Single-Product Case u Summary of last Session (Contd.)Monetary Applying Expected Value to Capacity Decisions Agenda for this Session Additional Chapter: Quality Control • Quality / Quality Control • Phases of Quality Assurance • Inspection • Statistical Control • Control charts • SPC Errors Agenda for this Session (Contd.) • Control Charts for Variables – Mean control charts – Range control charts • Counting Runs • Process capability ADDITIONAL CHAPTER: QUALITY CONTROL What is Quality ? • In manufacturing, a measure of excellence or a state of being free from defects, deficien cies and significant variations It What is Quality Control ? • Quality control (QC) is a procedure or set of procedures intended to ensure that a manufactured product or performed service adheres to a defined set of quality criteria or meets the requirements of the client or customer What is Quality Assurance ? • QC is similar to, but not identical with, quality assurance (QA) QA is defined as a procedure or set of procedures intended to ensure that a product or service under development (before work is complete, as opposed to afterwards) meets specified requirements QA is sometimes expressed together with QC as a single expression, quality assurance and control (QA/QC) 10 Use of p-Charts • • When observations can be placed into two categories – Good or bad – Pass or fail – Operate or don’t operate When the data consists of multiple samples of several observations each 33 Use of c-Charts • Use only when the number of occurrences per unit of measure can be counted; non-occurrences cannot be counted – Scratches, chips, dents, or errors per item – Cracks or faults per unit of distance – Breaks or Tears per unit of area – Bacteria or pollutants per unit of volume – Calls, complaints, failures per unit34of time Use of Control Charts • At what point in the process to use control charts • What size samples to take • What type of control chart to use – Variables – Attributes 35 Run Tests • • • Run test – a test for randomness Any sort of pattern in the data would suggest a non-random process All points are within the control limits the process may not be random 36 Nonrandom Patterns in Control charts • Trend • Cycles • Bias • Mean shift • Too much dispersion 37 Counting Runs Counting Above/Below Median Runs (7 runs) B A A B A B B B A A B Counting Up/Down Runs (8 runs) U U D U D U D U U D 38 NonRandom Variation • Managers should have response plans to investigate cause • May be false alarm (Type I error) • May be assignable variation 39 Process Capability • Tolerances or specifications – • Process variability – • Range of acceptable values established by engineering design or customer requirements Natural variability in a process Process capability – Process variability relative to specification 40 Process Capability Lower Specification Upper Specification A Process variability matches specifications Lower Specification Upper Specification B Process variability Lower Upper well within specifications Specification Specification C Process variability exceeds specifications 41 3 Sigma and 6 Sigma Quality Upper specification Lower specification 1350 ppm 1350 ppm 1.7 ppm 1.7 ppm Process mean +/ 3 Sigma +/ 6 Sigma 42 Improving Process Capability • Simplify • Standardize • Mistake-proof • Upgrade equipment • Automate 43 Taguchi Loss Function Traditional cost function Cost Taguchi cost function Lower spec Target Upper spec 44 Summary of the Session Additional Chapter: Quality Control • Quality / Quality Control • Phases of Quality Assurance • Inspection • Statistical Control • Control charts • SPC Errors 45 Summary of the Session (Contd.) • Control Charts for Variables – Mean control charts – Range control charts • Counting Runs • Process capability 46 THANK YOU 47 ... shift x-Chart LCL UCL Does not detect shift R-chart LCL 30 Mean and Range Charts Sampling Distribution (process variability is increasing UCL x-Chart LCL Does not reveal increase UCL R-chart... Reveals increase LCL 31 Control Chart for Attributes • • p-Chart - Control chart used to monitor the proportion of defectives in a process c-Chart - Control chart used to monitor the number of defects... Times for Stations, Systems, and Cycles Theory of Constraints Bottleneck Management Break-Even Analysis u Single-Product Case u Summary of last Session (Contd.)Monetary Applying Expected Value to