FICCI CE

FICCI CE

Variation Control

FICCI CE

Variation Control

Variation is a basic phenomenon of nature. This effects all entities including products and processes. Variation is found in all stages of product life cycle including design & development, manufacturing, service and supplier processes. Controlling process variation is a key to achieving WORLD CLASS quality.

FICCI CE

Understanding & controlling variation

Variation is responsible for the difference between one unit of product and another. It can also be defined as the difference between specifications and customer requirements. Variation is present in all processes. When it is present in one or more characteristics of a product or process, it causes poor quality and customer dissatisfaction.

FICCI CE

Understanding & controlling variation

Products and processes are expected to vary because no two things are exactly alike. Differences result from material characteristics, methods, people, machine and environmental factors as depicted on the next slide.

Variation

Methods•Procedures

•Policies•Accounting

Material•Assemblies•Components

•Suppliers•Consumables

Environment•Noise level•Humidity

•Temperature•Lighting

Sources of variation

People•Training

•Experience•Skill

•Attitude

Machine•Technology•Variability

•Tooling•Fixtures

Measurement•Counting

•Instruments•Gauging

•Tests

Causes of variation

Chance / Inherent Causes They have the influence on

the output all the time.

Causes

Special / Assignable CausesThey influence the output

only once in a while.

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Chance / inherent causes of variation

Chance or inherent causes are sources of variation which are always present because of small day-to-day variables. These causes are inherently part of the process (or system) and affect everyone working in the process. They are typically due to a large number of small random sources of variation. Chance causes also contribute to the output variability because they themselves vary.

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Chance / inherent causes of variation

Each chance/inherent cause typically contributes a small portion to the total variation in process outputs. Inherent causes usually have a nonsystematic, random appearance. Process or system variability is defined in terms inherent causes because they are regular contributors. The variables involved in inherent causes may change slightly from day to day, but this is natural. They will always be present, and the best way to stay ahead of this situation is to plan for it.

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Special / assignable causes

These are causes that do not occur naturally and are unusual. These types of causes are not inherent part of the process (or system) all the time or do not affect everyone but arise because of specific circumstances. Special causes are sporadic contributors and are due to some specific circumstances. Process or system variability is defined without them. Special causes can be identified and efforts can be made to minimize their influence on the process.

FICCI CE