Dimensions require tolerances
Design drawings or CAD models identify ideal dimensions required within given specifications.
The tolerance is the amount the value may vary above & below the nominal 'ideal' value.
The manufacturing processes inherently produce variation caused by:
- machine tool
- tooling
- materials
- operator
- poor gauging
- lack of maintenance
- measuring equipment
- lack of training
Good understanding of the requirements of a design drawing and tolerance types help minimise variation.
Emphasis must also be put on measuring techniques and equipment that are fit for purpose to verify these dimensions, and an understanding of any associated measurement uncertainties is imperative.
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Good practice online modules
- Dimensional
- Overview of basic design & interpretation of an engineering drawing
- An introduction to datum
- An introduction to geometric tolerancing
- An introduction to the designer's role in the design & interpretation of an engineering drawing
- An introduction to the manufacturer's role in the design & interpretation of an engineering drawing
- An introduction to the inspector's role in the design & interpretation of an engineering drawing