Automatic Generation of Assembly Instructions Using STEP

∗ S. Mok and K. Ong are currently Ph.D. and M.S. students of ECE at Northwestern University, Evanston, IL. Abstract An automatic method for generating assembly instructions using CAD files is presented in this paper. Algorithms for extracting geometrical information of objects stored in a non-proprietary format, ISO-10303, STEP-CAD data file are explained. The developed algorithms form an important link between design and manufacturing. In our previous work, we designed a hierarchical assembly model that allows designers to evaluate products for manufacturing cost using a structured assembly coding system (SACS). Each SACS code represents a sequence of assembling/disassembling operations for mating two parts. The developed algorithms in this paper will generate the required SACS codes based on the geometrical and topological information extracted from the STEP files of a product in a CAD environment. Based on the generated SACS codes, the proper assembly operations can then be derived for assembling the designed product. An example of assembly with simple parts is presented to verify the method.