Optimizing Locator Position to Maximize Robustness in Critical Product Dimensions

Abstract

The way parts are located in relation to each other or in fixtures is critical for how geometrical variation will propagate and cause variation in critical product dimensions. Therefore, more emphasis should be put on this activity in early design phases in order to avoid assembly and production problems later on. In earlier literature, locator positions have been defined using optimization to reach a robust locating scheme. This implies that the total robustness of a part is optimized by placing the locators in an optimal way. Sometimes there are areas on parts that are more sensitive to variation than others. Therefore, this paper suggests an approach for optimizing the positions of locators in a locating scheme to maximize robustness in defined critical dimensions. A formulation of an optimization problem is presented, and an algorithm solving this in a heuristic approach is developed. Finally, this algorithm is applied on an industrial example.

Fixture layout design based on two-stage method for sheet metal components

“…Qin et al 8 proposed to optimize fixture layout based on the degrees of freedom constrained. Lo¨o¨f et al 9 presented an approach for optimizing positions of locators in a locating scheme to maximize robustness in defined critical dimensions.…”

“…Rigid model Wang, 4 Wang and Pelinescu, 5 Cai et al, 6 Carlson and Sö derberg, 7 Qin et al, 8 Lö ö f et al, 9 Vishnupriyan et al, 10 Fan and Senthil Kumar 16 Kim and Ding 3 , Izquierdo et al, 12 Phoomboplab and Ceglarek, 13 Huang et al 14 Sheet metal parts Cai et al, 6 Cai1 5 , Xing et al, 17 Xing 18 Camelio et al 11 In order to evaluate different fixture schemes, the displacement of all the nodes in the surface is used as the objective function as shown in equation ( 1)…”