BS8888 Geometric Dimensioning & Tolerancing

This course will examine the BS8888 standard for Geometrical Dimensioning & Tolerancing (GD&T), as well as offer a comparison with the American ASME standard and incorporate the ISO standards.

GD&T is used to control the form, location and orientation of features and emphasises that, for assemblies to function correctly, the designer cannot rely on the tolerancing of size alone. The course stresses the need to dimension in a way that will complement the function of the part. The result of correctly applying GD&T is that the size of the tolerances will be as large as possible to allow the component to function correctly, therefore the result will be cheaper components that are of a higher quality.

Course Content

Definition of Geometrical Tolerances
- What is a tolerance (part, assembly, functional tolerances)
- Why we need tolerances & how to use them
- Why some geometrical tolerances can contain others

Applying Tolerances to a Drawing
- Calculating the size of tolerances
- Worst case scenario
- Statistical process tolerances

Tolerance Frame
- How to apply GD & T to a point, axis, edge or surface
- Common errors

Tolerance Feature & Datum Feature
- Group datum
- Datum restriction or tolerance restriction

Interpretation of Geometric Tolerances
- Single features
- Related features

Maximum Material Condition
- Understanding what happens when components are not manufactured on worst case conditions
- Fully understanding the function and applying suitable tolerances

Application of Tolerances
- Syndicate work on components
- Geometric tolerancing applied to assembly procedure

ISO Standards
- Tolerancing of form BS ISO 1101
- Maximum material condition BS ISO 2692
- Positional tolerancing BS EN ISO 5458
- Datums and datum-systems for geometrical tolerancing BS ISO 5459