- The part must always be clamped to the
fixture in such a way that it sits neither distorted nor loose. To this end, clamping systems or (in case of smaller and lighter parts) masticated rubber can be used.
- parts should always be clamped in such a way that they are not fixed on all corners. This allows the part to "work", i.e., it can always react to the existing variations in temperature and does not get distorted. Guiding principle: use a 3-2-1 clamping setup. (This means that the part should be fixed in a 1st position in all three directions of space (x, y, z), in a 2nd position only in 2 directions of space (y, z) and in a 3rd position only in one direction of space (z).)
- The part should never be fixed at the edge of the measuring range of the CMM, but always in the optimum measuring range. To be able to do so, you must know the CMM and its optimum measuring range.
- Clamping by means of magnets should be avoided for high precision measurements, for example gages. The reason for this is that the magnetic effect not only affects the part but also the steel stylus tip of the stylus system. This will falsify the measuring result.
- If the part is measured for the purpose of evaluation of
manufacturing process, make sure that the part is measured in the original clamping setup
as in manufacture. A temporary unclamping, followed by reclamping, should be avoided. Guiding principle: For measuring, use same clamping setup as for machining.
- If the part is measured for the purpose of evaluation of function, it must be measured in the unclamped state. This means that no force must act on the part. Guiding principle: Measure functions only in the unclamped state.
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Aluminum clamping device in modular design (Horst Witte Gerätebau)
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