Dimensioning and tolerancing by the coloured contacts method

  • Éric Pairel Université de Savoie Mont Blanc, Laboratoire SYMME, Polytech Annecy-Chambéry
Keywords: geometry, GD&T, dimensions chain, tolerancing


The dimensions chain method, very used in mechanical design, makes it possible to determine the dimensions of the parts on which depend the clearances necessary in the mechanism they constitute. Unfortunately, no method can correctly determine the places in the mechanism in which these clearances must be introduced and configured. This remains dependent on the intuition of the designer who must, in addition, make a particular drawing of the mechanism that exaggerates these clearances. Errors are frequent. The presented coloured contacts method makes it possible to identify, in a systematic and exhaustive way, the functional clearances for the mechanism and then the dimensions of the parts on which they depend. This method represents a major advance for the functional dimensioning and tolerancing of the mechanisms. It is accompanied here by a method of calculating tolerance intervals of distances and dimensions on a relatively complex example.

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