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Part 1 : System Management.

Ch.8 Quality Management.

Edited by Dr. Seung Hyun Lee (Ph.D., CPL)

IEMS Research Center, E-mail : lkangsan@iems.co.kr

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■ Definition of Quality. [APICS Dictionary]

Fitness for Use (Design Quality). - A term of quality used to indicate that a good or service fits the customer's defined purpose for that good or service. - Design quality.

Conformance (Manufacturing Quality). - An affirmative indication or judgement that a product or service has met the requirements of a relevant specification, contract, or regulation.

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■ Quality Cost. [Other Resource]

Failure Costs. - Internal failure costs. ․ The cost of correcting problems that occur while the goods are still in the floor. ․ Scrap, rework, and spoilage.

- External failure costs. ․ The cost of correcting problems after goods or services have been delivered to the customer. ․ Warranty cost, field servicing of customer goods, and all the other costs associated with trying to satisfy customer complaints.

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■ Quality Cost. [Other Resource]

Control Costs. - Appraisal costs. ․ The costs associated with checking and auditing quality in the organization. ․ Product inspection, quality audits, testing, and calibration.

- Prevention costs. ․ The costs of avoiding trouble by doing the job right in the first place. ․ Training, statistical process control, machine maintenance, and quality planning costs.

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■ Quality Assurance and Control.[APICS Dictionary]

Quality Assurance. - All the planned and systematic activities implemented within the quality system that can be demonstrated to provide confidence that a good or service will fulfill requirements for quality. - Quality assurance can mean the act of giving confidence, the state of being certain, or the act of making certain. - Quality assurance applications. ․ End items, Components and Raw Materials. ․ Operations. ․ Supplies in storage. ․ Maintenance operations. ․ Data or records. ․ Administrative procedures.

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■ Quality Assurance and Control.[APICS Dictionary]

Quality Control. - The operational techniques and activities used to fulfil requirements for quality. - Quality control can mean an evaluation to indicate needed corrective responses, the act of guiding, or the state of process.

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■ Total Quality Management.[Other Resource]

Definition. An effective system for integrating the quality development, quality maintenance, and quality improvement efforts of the various groups in an organization so as to enable production and service at the most economical levels which allow for full customer satisfaction.

TQM is based on the participation of all members of an organization in improving processes, goods, service, and the culture in which they work.

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■ Total Quality Management.[Other Resource]

Basic Elements of TQM. - A committed and involved management directing and participating in the quality program. - Focus on the customer : Internal & external customer. - Employees involvement . - Continuous process improvement. - Supplier partnership.

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■ Total Quality Management.[Other Resource]

External customers. External customer exist outside the organization and purchase goods or service from the organization.

Internal customers. Persons or departments who receive the output from another person or department in an organization.

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■ Total Quality Management.[Other Resource]

Employee Involvement. The concept of utilizing the experience, creative energy, and intelligence of all employees by treating them with respect, keeping them informed, and including them and their ideas in decision-making process appropriate to their area of experience.

Quality at the source. Quality at the source refers to a producer's responsibility to provide 100 percent acceptable quality to the consumer of the material.

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■ Total Quality Management.[Other Resource]

Continuous Improvement. Process improvement is the activities designed to identify and eliminate causes of poor quality process variation, and non-value-added activities. Continuous improvement requires a long-term perspective and the support of top management. Continuous improvement incorporates efforts to act upon both chronic and sporadic problems and refinements to processes.

Supplier Partnership : Single Sourcing. It is a planned decision by the organization to select one supplier for an item when several sources are available. It is intended to produce a long-term partnership.

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■ Inspection.[Langford, pp85-124]

Definition. The examination or testing of supplies and services.

Consideration for Inspection. ․ The type of product to be inspected. ․ The quality characteristics to be examined for conformance. ․ The quality history of the producer. ․ The cost of inspection. ․ The effect of inspection upon the unit of product. (i.e., destructive or nondestructive)

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■ Sampling Inspection.[Langford, pp85-124]

Advantages of Sampling Inspection. ․ It provides a check on the adequacy of process control. ․ The inspection labor force can be smaller or more economically used. ․ There is less handling damage to the product. ․ The product is disposed of in shorter time between improves delivery scheduling. ․ An inspector using a lot-by-lot sampling plan would have less boredom and possible error compared to 100 percent inspection. ․ The total rejection of an entire lot or batch of nonconforming product dramatizes the need to take corrective action.

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■ Sampling Inspection.[Langford, pp85-124]

Sampling Disadvantages. ․ The ever present risk of rejecting good product and accepting bad product. ․ The costs associated with the administration of rigorous acceptance plans. ․ Less product information is obtained compared to more intensive inspection.

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■ Data Characteristics.[Other Resource]

Attribute data ․ A measurement made when the characteristics being measured can take on only certain specific values, such as no. of defects/defectives.

Variable data ․ A measurement made in cases where the characteristic being measured can take on any value, such as weight, size, time, and so on.

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■ Common Sampling Standard.[Langford, pp85-124]

MIL-STD-105 (ANSI/ASQ Z1.4) ․ These tables are sampling plans for attributes. ․ There are three types of sampling used : 1. Single sampling : The decision to accept or reject is based on one sample. 2. Double sampling : The decision to accept or reject a lot is based on a maximum of two samples. 3. Multiple sampling : The decision to accept or reject the lot is based on a maximum of seven samples.

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■ Common Sampling Standard.[Langford, pp85-124]

MIL-STD-414 (ANSI/ASQ Z1.9) ․ These tables are sampling plans for variables.

Dodge-Roming Tables. ․ Effective sampling inspection when the process average is known.

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■ Operating Characteristics (OC) Curve.[Langford, pp85-124]

Sampling risks : ․ Good product is rejected. (the producer or alpha α risk)

․ Bad product is accepted. (the consumer or beta β risk)

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■ OC Curve (cont).[Langford, pp85-124]

Role of OC Curve. The Operating Characteristics (OC) curve for a sampling plan quantifies these risks.

An "ideal" OC curve.

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■ OC Curve (cont).[Langford, pp85-124]

Acceptable quality level (AQL) ․ The worst quality level that is still considered satisfactory. ․ The maximum percent defective that for purpose of sampling inspection, can be considered satisfactory as a process average.

Rejected quality level (RQL) ․ Unsatisfactory quality. ․ Lot tolerance percent defective (LTPD) - Dodge-Roming plans. ․ The probability of accepting a RQL lot should be low. In some tables, this is known as the consumer's risk and has been standardized at 0.1

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■ OC Curve (cont).[Langford, pp85-124]

Indifference quality level (IQL) ․ This is a quality level somewhere between the AQL and RQL. ․ It is normally defined as the quality level having probability of acceptance of 0.50.

n =

100 c + 67

Indifference Quality (in percent defective)

where n = Sample size. c = Acceptance number

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■ OC Curve (cont).[Langford, pp85-124]

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■ Severity of Inspection[Langford, pp85-124]

Reduced Inspection ․ Reduced inspection may be implemented when it is evident that quality is running well.

Normal Inspection Level Ⅱ ․ Inspection level Ⅱ is used when there is no evidence that the quality of product being submitted is better or poorer than the specified quality level.

Tightened Inspection ․ Under tightened inspection, the inspection plan requires more stringent acceptance criteria.

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■ Average Outgoing Quality Limit. [Other resource]

AOQL : Average Outgoing Quality Limit. The average quality of outgoing product, including all accepted lots or batches plus all rejected lots or batches after they have been effectively screened and defectives removed or replaced by nondefectives.

Calculation of AOQL.

AOQL = p × Pa

where, p = % defective.

Pa = Probability of acceptance.

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■ Calculation of AOQL[Other resource]

Example of AOQL : N=150, c=3.

np p % Pa AOQDecimal Percent

0.00 0.0 1.00 0.0000

0.75 0.5 0.99 0.4965

1.50 1.0 0.93 0.9340

2.25 1.5 0.81 1.2135

3.00 2.0 0.65 1.2940

3.75 2.5 0.48 1.2100

4.50 3.0 0.34 1.0260

5.25 3.5 0.23 0.8120

6.00 4.0 0.15 0.6040

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■ Process Improvement & Control.[Other resource]

Steps of Process Improvement. Step 1. Choose a process. Step 2. What are the goals the what are we trying accomplish with this process ? Step 3. Choose measurements. Step 4. Measure output reliability. Step 5. Take the process apart piece by piece. Step 6. Eliminate waste. Step 7. Simplify, fix, train. Step 8. Measure output again. Step 9. Repeat from number 6.

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■ Process Improvement & Control.[Other resource]

Objectives for Process Improvement. 1. No. of defectives. 2. Setup time. 3. Lot sizes. 4. Material handling. 5. Move distances. 6. Transportation costs. 7. Paper work. 8. Number of suppliers. 9. Number of part numbers.

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■ Process Improvement & Control.[Other resource]

Tools for Process Improvement.

Quantitative Qualitative․ Pareto Chart․ Histogram․ Statistical Control Chart․ Scatter Diagram․ FTA․ Criticality Analysis․ Process Capability Index

․ Cause & Effect Diagram․ Process Flow Chart․ Brainstorming․ Contingency Planning.․ FMEA.․ 5 Why's․ Check lists

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■ Process Improvement & Control.[Other resource]

Process Control : Two sets of sources for error ․ Common(Random) Causes Errors introduced into the process that come from common causes occur because of the randomness of the process or the inability of the process to repeat precisely everytime.

․ Special(Assignable) Causes Errors introduced into the process that come from special causes are controllable, can be identified, and can be eliminated.

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■ Design For Quality. [Other resource]

Quality Function Deployment(QFD) : Definition. A structured process or mechanism for determining customer requirements and translating them into relevant technical requirements that each functional area and organization level can understand and act upon. It also includes the appropriate monitoring and control of the manufacturing process to achieve the goal

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■ Design For Quality. [Other resource]

House of Quality.

Correlation matrix

Counterpart technical requirements

(HOWS)

Relationship matrix

Technical assessment and target values

Marketinginformation

and customerperception of

existing/competingproducts

Customerrequirements and

rating of importance

(WHATS)

1.

2.

3.

4.

5.

6.

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■ Design For Quality. [Other resource]

Quality Function Deployment(QFD) : Advantages. Creates a customer driven environment. Reduces the cycle time for new products. Uses concurrent engineering methods. Reduces design to manufacturing costs (fewer changes) Increase communications through cross functional teams. Creates data for proper documentation of engineering knowledges. Establishes priority requirements and improves quality.

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■ Design For Quality. [Other resource]

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Performance Check.

1. A fishbone diagram is an example of which of the following ? A. A cost buildup method. B. Organization method. C. Capability analysis. D. Another name for Pareto analysis.

2. Which of the following will ensure quality in manufacturing parts ? A. Applying as much automation as possible. B. Inspecting all parts for known defectives. C. Improving customer warranty coverage. D. Reducing the variation in the process.

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Performance Check.

3. Which of the following statements is TRUE ? A. In the long run, quality is more expensive but necessary for survival in today's business world. B. Most companies spend less than 10 percent on quality-related activities. C. In the long run, quality is less expensive. D. Quality-related costs (failure costs) are an integral part of doing business and should be built into every product cost buildup.

4. Which of the following statements is TRUE regarding Pareto analysis ? A. It separate the significant few from the trivial many. B. It uses the six categories of quality. C. It is an extension of the 50-50 rule of quality. D. It assigns weighted costs associated with internal versus external failure costs.

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Performance Check.

5. Which of the following statements is BEST regarding building quality into products ? A. It is very difficult to do. B. It is most easily accomplished through automations. C. It is best accomplished by production workers. D. It is the responsibility of the quality inspectors.

6. Which of the following would be considered the MOST important factor in supplier selection ? A. Proximity to the plant. B. Lowest price. C. Product quality. D. Reciprocal arrangements.

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Performance Check.

7. A control chart is primarily used to determine which of the following ? A. The percentage defective in the goods being produced. B. The specification limits. C. The capability of the process. D. Normal variation versus assigned variation.

8. Quality at the source suggests that the quality of the product is determined at the instant the product is made. If is true, then which of the following is also TRUE ? A. The idea of the external customer leads to the concept of quality at the source B. Inspection is not necessary C. Quality is not the manufacturer's responsibility D. Quality should be the responsibility of one department within the company

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Performance Check.

9. A statistical control chart distinguishes between special-and common-cause variation through which of the following ? A. Distribution curve B. Sample size C. Histogram D. Control limits

10. A process capability analysis provides which of the following ? A. Quantified prediction of process adequacy B. Performance summary C. Status report D. Qualitative summary of process adequacy

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Performance Check.

Solutions.

1 2 3 4 5 6 7 8 9 10

B D C A C C D B D A