Geometrical Tolerancing
Five Common misconceptions about
 Geometrical Tolerancing
1 We've always managed fine without it.

You may have got away without using it, but sooner or later you won't.  It is not technically possible to fully define component geometry without it, unless an extraordinary number of plain language notes are used.

 2 Geometrical tolerancing just makes drawings more complicated.

 Drawings can look more complicated just because of a lack of familiarity with, and understanding of, the symbology.

Drawings can also look more complicated because, properly used, geometrical tolerancing will be controlling aspects of work-piece geometry which were previously not controlled at all.  Drawings contain more annotation simply because they are more complete specifications.

Geometrical tolerancing can actually make drawings simpler

 3 Geometrical tolerances are more difficult to inspect.

 Geometrical tolerancing, properly used, makes inspection easier.

It also removes ambiguity from the specification, so it becomes possible to give a more definite pass/fail result for a component.

 4  Use of geometrical tolerancing makes parts more expensive
No it doesn't.  Suppliers who don't understand geometrical tolerancing sometimes use it as an excuse to increase prices, but there is no justification for this.

Properly used, geometrical tolerancing enlarges tolerance zones and improves productivity.  Its use should lead to a reduction in cost.

 5 Our suppliers don't understand it, so there is no point in using it.

 It is a fact that many UK suppliers do not understand geometrical tolerancing properly, just as in many cases their customers do not.

Anecdotal evidence suggests that their competition, suppliers from India, China, the Pacific rim, etc, are not only cheaper, and frequently quicker, but also understand geometrical tolerancing far better than their UK counterparts.

UK suppliers have to get up to speed with geometrical tolerancing, or they simply won't survive.

Avoiding the use of geometrical tolerancing, and missing out on all its potential benefits, is not a long term solution for anyone.
What is Geometrical Tolerancing?

Geometrical Tolerancing is a system that allows tolerances to be applied to features rather than dimensions on engineering drawings. It allows different aspects of form, orientation and location to be toleranced independently of each other. This allows tolerances to reflect the functions and relationships that the designer intends. Advantages include:-
  • productivity can be improved without relaxing tolerance requirements


  • tolerance zones can often be enlarged


  • form requirements like roundness and flatness can be toleranced


  • relationships like coaxiality can be toleranced


  • complex surfaces can be toleranced


  • drawings are less ambiguous and can even be simplified

Geometrical tolerancing is no longer a special tool to be dusted off for awkward geometry and high precision requirements.  It is a better way of applying tolerances to all features, and is central to the Geometrical Product Specification methodology.

The greater flexibility and precision of this system allows engineers and designers to document design intent more accurately and more completely.  An understanding of this system is increasingly a contractual requirements, and manufacturing organisations cannot afford to remain in ignorance of it.
 Public Course in Geometrical Tolerancing

Although almost all our business consists of running in-house training courses for our clients, we occasionally put on public, or open, courses in geometrical tolerancing, which you can book individual places on.

If you email us to register interest (with no commitment on your part), we will email details to you next time we plan to run a public course.