Abstract
Abstract
A graph theoretical approach is presented that permits the calculation of optimal process plans from datum hierarchy trees, which are elegant representations of tolerance charts. The theory is developed for a cost function that minimizes machine and datum changes. Restrictions on the sequence of machining operations arising from technical constraints or the layout of a group cell are taken into account. The process plans are optimal with respect to a specified datum hierarchy tree, manufacturing constraints and cost function. It is shown that the number of possible plans for real industrial trees is very large, and therefore this kind of optimization is beyond the ability of a human process planner. Trial runs with industrial parts indicate that optimization can be performed by a computer within a time period that is acceptable for industrial use.