Optimizing plastic gear geometry: an introduction to gear optimization

There are numerous engineering evaluations required to design gear sets for optimum performance with regard to torque capacity, noise, size and cost. How much cost savings and added gear performance is available through optimization? Cost savings of 10% to 30% and 100% added capacity are not unusual. The contrast is more pronounced if the original design was prone to failure and not fit for function. Development of the gear geometry is a critical part of the total design process. This article will summarize the design issues relating to optimizing gear geometry. All interrelated parameters that comprise the gear description are candidates for optimization. Those parameters include pitch, pressure angle, helix angle, addendum modification, root clearance, face width, root and tip radii, tooth thickness, center distance and profile modifications. One design parameter, total working depth, will be evaluated as an example of the potential benefit of gear optimization.