Tolerance control for dimensional and geometrical specifications

The development of tolerance charts has come a long way from the past manual methods to the current computer-aided models. As a result, many techniques have emerged over the years. However, the area of geometrical tolerance charting has not been given much attention. In view of this, this paper addresses both linear and geometrical tolerance control.The method proposed in this paper allows the user to construct a model directly from the process plan. The relevant process links between any two planes which are required to satisfy both the linear and geometrical requirements are easily obtained from the model. Having established all the appropriate constraints, the linear programming optimisation software is used for the determination of the unknown working dimensions and tolerances.In essence, this paper presents a new methodology for deriving the process links from the process plan and also highlights the significance of the use of linear programming in achieving the optimal tolerance mix or combination.