TOLERANCING - Tolerancing and Interchangeability

Previous        Next

 

Tolerancing and Interchangeability

 

Lecture content

Tolerancing is dimensioning for interchangeability.

 

What is interchangeability?

 

An interchangeable part is simply a mass produced part (a replacement part).

 

How is a feature on an interchangeable part dimensioned?

 

A single value dimension (1.00) now becomes a range of values (.995 - 1.005).

 

A tolerance is the amount of size variation permitted. You can choose a tolerance that specifies a large or small variation.

 

Tolerance = max. size - min size

 

Why do we want a part’s size to be controlled by two limits?

 

It is necessary because it is impossible to manufacture parts without some variation. The stated limits are a form of quality control.

 

Lecture content

Choosing a tolerance for your design.

 

Specify a tolerance with whatever degree of accuracy that is required for the design to work properly. Choose a tolerance that is not unnecessarily accurate or excessively inaccurate. Choosing the correct tolerance for a particular application depends on:

 

  • the design intent (end use) of the part
  • cost
  • how it is manufactured
  • experience

 

Previous        Next