1. Introduction to Quality and Quality Control

1.1 Introduction to Quality :

Concept of Quality
Simply, quality refers to one or more desirable characteristics that a product should possess.

Quality is inversely proportional to (unwanted) variability.

 
 
Quality Characteristics:
Every product possesses a number of properties that jointly describe what the user or consumer thinks of as quality. These properties are known as quality characteristics.
For example, fiber length is known to be one of the important quality characteristics of a fiber.
Quality Cost :
Preventing, detecting and dealing with defects cause costs that are calledquality costs or costs of quality.
Quality costscan be broken down into four broad groups.
(1). Prevention Costs:
product/process design.
Process control.
Burn-in.
Training.
Quality data acquisition and analysis.
(2)Appraisal Costs:
Inspection and test of incoming material.
Product inspection and test.
Material and services consumed.
Maintaining accuracy of test equipment.
(3).Internal failure Costs:
Scrap
Rework
Retest
Failure analysis
Downtime
Yield losses
Downgrading/ off-spacing
(4). External failure costs:
Complaint adjustment
Returned product/material
Liability costs
External costs
Quality history [1]
Year
Event
1700-1900
Quality was largely determined by the efforts of an individual craftsman.
1915-1919
WWI- British government began a supplier certification program.
1919
Technical Inspection Association was formed in England, this later becomes the Institute of Quality Assurance.
1924
W A Shewhart introduced the concept of control charts in Bell Laboratories technical memorandum.
1928
Accepatance sampling techniques were developed and refined by H. F. Dodge and H. G. Romig at Bell Labs.
1931
W. A. Shewhart published Economic control of quality of manufactured product outlining statistical methods for use in production and control chart methods.
1932-1933
British textile industry began use of statistical techniques for product/process development.
1944
Industrial Quality Control began publication.
1954
E. S. Page introduced CUSUM control chart.
1960
The concept of quality control circle was introduced in japan by K. Ishikawa.
1960
The zero defects (ZD) programs are introduced in US induatries.
 
 
 
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