class 02 - basic concepts of quality control1

8/11/2019 Class 02 - Basic Concepts of Quality Control1

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History of Quality Control

History ofQualityControl

Dimensions

of Quality

Quality

Characteristics

Industrial Engineering

History of Manufacturing


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Dimensions

of Quality

Quality

Characteristics


The factory system, with its emphasis on product inspection, startedin Great Britain in the mid-1750s and grew into the Industrial

Revolution in the early 1800s. Late in the 19th century the United States adopted a new

management approach developed by Frederick W. Taylor. In 1875Taylor introduced the principles of scientific management; dividingwork into tasks with standardized procedures

Gilbreth developed standard times and motions (1920s)

Walter Shewhart, a statistician for Bell Laboratories, in1924 began tofocus on controlling processes, making quality relevant not only forthe finished product but for the processes that created it. Shewhartsconcepts are referred to as statistical quality control (SQC).

Dodge and Romig (1928), Bell Labs, develop acceptance samplingas an alternate to 100% inspection.

W Edwards Deming, a statistician with the U.S. Department ofAgriculture and Census Bureau, became a proponent of ShewhartsSQC methods and later became a leader of the quality movement inboth Japan and the United States


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Dimensions

of Quality

QualityCharacteristics


Demings Theory of Quality & Economics

Improve

Quality

Costs decrease because of

less rework, fewer

mistakes, fewer delays,

snags; better use ofmachine-time and materials

Productivity

Improves

Capture the

market with

better qualityand lower price

Stay in

business

Provide jobs

and more jobs


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Dimensions of Quality


Dimensionsof Quality



Demings 14 Points

Constancy of purpose

New philosophy

Cease inspection

Move beyond price

Improve constantly

Job training

Modern supervision

Drive out fear

Break down barriers

Eliminate slogans

Eliminate quotas

Promote pride

Education & retraining

Top management commitment


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Dimensions

of Quality




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1. PerformanceThe primary operating characteristics of the product or service. Will theproduct perform its intended function?

2. Features

The characteristics that supplement the basic functioning of the product or

service. What will the product do beyond the basics?

3. Reliability

Probability of the product or service failing within a specified period oftime. How often does the product fail?

4. Conformance

The degree to which a product or service meets acknowledged standards.Is the product made as designed?



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5. Durability

A measure of product life (both technical and economic). How long will theproduct last?

6. Serviceability

The speed, courtesy, competence, and ease of repair or recovery. Howeasy is it to repair the product?

7. Aesthetics

How a product or service looks, feels, sounds, tastes, or smells. Is theproduct pleasing to the senses?

8. Perceived Quality

Various tangible and intangible aspects of the product from which quality isinferred. What is the reputation of the company selling this product?




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Dimensions of Service Quality

TangiblesAppearance of facilities, equipment, personnel

Reliability

Promised service dependably and accurately

Responsiveness

Willingness to help, prompt service

Assurance

Knowledge, courtesy, trust, confidence

Empathy

Caring, individualized attention




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Quality Characteristics



Example

Quality is inversely proportional to variability

Toyota Lexus versus Ford Taurus

That transmission noise is wasted energy caused by components thatdont fit precisely. Imprecise components lead to wear and tear. FordTaurus/Mercury Sable transmission lasts for 64,000 miles.Dimensions

of Quality



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Introduction

Dimensions

of Quality




Physical : length, weight, voltage, viscosity

Sensory : taste, appearance, color

Time Orientation : reliability, durability, serviceability

Two types of data:

Attributes Data - discrete data, often in the form of counts

Variables Data - continuous measurements such as length, weight



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Dimensions

of Quality


Specifications

Quality characteristics being measured are often compared tostandards or specifications. Desired measure for the qualitycharacteristic.

Nominal or target value

Upper Specification Limit (USL)

Lower Specification Limit (LSL)

Largest and smallest allowable values

When a component or product does not meet specifications, it isconsidered to be nonconforming.

A nonconforming product is considered defective if it has one or morenonconformities that may seriously affect the safe or effective use of

the product.




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Dimensions

of Quality


The Link Between Quality and Productivity

Effective quality improvement can be instrumental in increasingproductivity and reducing cost.

The cost of achieving quality improvements and increasedproductivity is often negligible.

Internal failure costs: Scrap, Rework, Retest, Failure analysis,Downtime, Yield losses, Downgrading

External failure costs : Complaint adjustment, Returnedproduct/material, Warranty charges, Liability costs, Indirect costs



class 02 - basic concepts of quality control1

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