Immobilization check for fixture design

Fixture design contributes highly to manufacturing safety and quality. Computer aided fixture design (CAFD) facilitates more cost effective and efficient workholder design. However, heuristic and case-based approaches are still common. This paper addresses CAFD using the computational geometry approach. The correctness of a fixture design will be determined through vector-theoretic immobilization checking of the fixture points (i.e. location and clamping points) proposed. Details of the translational and rotational immobilization checking theory are explained, which are also applicable to general three-dimensional shapes. In real life, perfect geometry does not exist. As contemporary CAFD systems cannot cater for non-ideal geometry satisfactorily, the paper also develops an interval analysis scheme for toleranced immobilization checks. A real-life case study is presented to demonstrate the procedure.