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Lecture No. 11 _ 12

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					Production & Operations Management
Session 11-12

Prepared by M.Latif
Production Management (Sweden)

Superior College/University

1

Learning Objectives
1. Basics of Quality

2. Various Concepts in TQM
3. TQM Tools

4. Statistical Process Control

Superior College/University

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Definitions of Quality
Product characteristics & features that affect customer satisfaction User-Based: What consumer says or wants. Manufacturing-Based: Degree to which a product conforms to design specification Product-Based: Level of measurable product characteristic

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Dimensions of Quality for Goods
 Reliability & durability  Conformance  Serviceability  Appearance

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Service Quality Attributes are levels of
Reliability
Understanding

Responsiveness
Competence

Security
Credibility Communication
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Access Courtesy
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Costs of poor quality “are huge, but the amounts are not known with precision. In most companies, the accounting system provides only a minority of the information needed to quantify this cost of poor quality
Juran on Quality by Design

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Various Concepts in TQM
 Continuous improvement  Employee empowerment  Benchmarking  Just-in-time (JIT)  Taguchi concepts  Knowledge of TQM tools

Superior College/University

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Shewhart’s PDCA Model

Implement Identify the improvement and the plan make a plan Is the plan working

4.Act

1.Plan

3.Check

2.Do

Test the plan

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Employee Empowerment
Getting employees involved in product & process improvements
Because 85% of quality problems are due to process & material

Techniques
Support workers Let workers make decisions Build teams & quality circles

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Quality Circles
Group of 6-12 employees from same work area Meet regularly to solve work-related problems
4 hours/month is enough

Facilitator trains & helps with meetings

Superior College/UniversityCorel Corp. © 1995

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Resolving Customer Complaints Best Practices
 Make it easy for clients to complain  Respond quickly to complaints  Resolve complaints on the first contact  Use computers to manage complaints  Recruit the best for customer service jobs

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Just-In-Time (JIT) Example
Reducing inventory reveals problems that need to be solved.

Unreliable Vendors
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Scrap

Capacity Imbalances
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Taguchi Techniques
 If the quality of the product is not good then it is a loss to society. Product has failure either in characteristics, performance or harmful side effects  Taguchi proposes three principal tools for quality engineering to avoid loss to society
 System Design  Parameter Design  Tolerance Design.

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Tools of TQM
 Check sheet  Scatter diagram  Histograms  Pareto charts  Process charts (Flow diagrams)  Cause and effect diagram  Statistical process control chart

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Check Sheets
An organized method of recording data

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Scatter Diagram
 A graph of the value of one variable vs. another variable.

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Histogram
 A distribution showing the frequency of occurrences of a variable usually along time axis

Superior College/University

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Pareto Analysis of Glass Defects (Total Defects = 77)
70

Frequency (Number)

50 40 30 20 10 0
Scratches

60% 40% 12 6.5
Nicks

5
Contamination

2.5
Misc.

20% 0%

Porosity

70%

Causes, by percent total 5% defects 16% 6.5%

2.5%

A graph to identify and plot problems or defects in descending order of frequency
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Cumulative Percent

60

54

86% 70%

93%

98%

100% 100% 80%

Process Chart
 Shows sequence of events in process  Depicts activity relationships  Identify data collection points

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Cause and Effect Diagram
 Used to find problem sources/solutions  Other names
 Fish-bone diagram, Ishikawa diagram

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Cause and Effect Diagram Example

Problem
Too many defects

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Cause and Effect Diagram Example
Method Main Cause Too many defects Manpower

Material

Machinery Main Cause

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Cause and Effect Diagram Example
Method Drill Manpower Overtime Too many defects Wood Steel Material Machinery Sub-Cause
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Lathe

Cause and Effect Diagram Example
Method Drill Slow Manpower Tired Overtime Old Too many defects

Wood Steel Material Machinery

Lathe

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TQM In Services
 Service quality is more difficult to measure than for goods  Service quality perceptions depend on
 Expectations versus reality  Process and outcome

 Types of service quality
 Normal: Routine service delivery  Exceptional: How problems are handled

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Determinants of Service Quality
Reliability – consistency and dependability Responsiveness – willingness/readiness of employees to provide service; timeliness Competence – possession of skills and knowledge required to perform service Access – approachability and ease of contact Courtesy – politeness, respect, consideration, friendliness of contact personnel

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Determinants of Service Quality Continued
 Communication – keeping customers informed in languages they understand  Credibility – trustworthiness, believability, honesty  Security – freedom from danger, risk or doubt  Understanding/knowing the customer – making the effort to understands the customer’s needs

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Statistical Quality Control (SPC)
 Measures performance of a process  Uses mathematics (i.e., statistics)  Involves collecting, organizing, & interpreting data  Objective: provide statistical signal when assignable causes of variation are present  Used to
Control the process as products are produced Inspect samples of finished products
Superior College/University
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Statistical Process Control (SPC)
Statistical technique are used to ensure that process is making product to the set standard. All process are subject to variability
Natural causes: Random variations Assignable causes: Correctable problems
Machine wear, unskilled workers, poor material

Objective: Identify assignable causes Uses process control charts

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Process Control Charts
Plot of Sample Data Over Time
80

Sample Value

60 40 20 0 1 5 9 13 Time 17 21

Sample Value UCL Average LCL

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Process Control: Three Types of Process Outputs
(a) In statistical control and capable of producing within control limits. A process with only natural causes of variation and capable of producing within the specified control limits. Upper control limit (b) In statistical control, but not capable of producing within control limits. A process in control (only natural causes of variation are present) but not capable of producing within the specified control limits; and
Size (Weight, length, speed, etc. )

Frequency Lower control limit

(c) Out of control. A process out of control having assignable causes of variation.
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Superior College/University

Control Chart Purposes
Show changes in data pattern
e.g., trends
Make corrections before process is out of control

Show causes of changes in data
Assignable causes
Data outside control limits or trend in data

Natural causes
Random variations around average

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Control Chart Types
Continuous Numerical Data Control Charts Categorical or Discrete Numerical Data

Variables Charts R Chart
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Attributes Charts X Chart P Chart C Chart

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posted:7/30/2009
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