Optimization of StepLock® Orthotic Knee Joint Design

Concurrent and early application of DFM, DFMA, FEA, and DFE methodologies in biomedical products can yield significant benefits to companies involved in the design and development of products such as orthotics. In these cases, nearly 70-80% of the orthotic cost is already committed during the design phase leaving much less than 20% of product cost for optimization during the manufacturing phase. Thus, attempts to reduce orthotic cost, and increase robustness of product performance become an uphill task due to limited scope for optimization during the manufacturing phase. Currently, most of the design and manufacturing work in the orthotic industry does not incorporate all available robust design tools during the concept stage of product development. Consequently, many times the manufacturing process results in line stoppers; parts not assembling correctly; endless engineering change orders; pruning, grooming, tuning to get the part out of the door. This paper presents the integration of DFM, DFMA, FEA, and DFE principles early in the design phase of orthotics, coupled with the use of CREO® for generation of CAD models, DFM-Pro® for improving manufacturability, CustomPart. Net for cost reduction, and Sustainable Minds® for reducing carbon footprint. In this study StepLock® orthotic knee joint design optimization resulted in a 50% reduction in number of features, 37% reduction in number of parts, 2% reduction in weight, 50% reduction in Von-Mises stresses, 44% reduction in maximum shear stresses, 47% reduction in cycle time, 49% reduction in manufacturing cost, and 95% reduction in carbon footprint. This study demonstrates successful implementation of robust design tools in the production of environmentally benign biomedical products and reducing carbon footprint, while simultaneously increasing robustness and reducing cost.