LAUSR

Abstract Plastic gears have many advantages over traditional metal gears, including a lower weight, better design flexibility and an improved ability to absorb shock and vibration. Moreover, they are easily produced by plastic injection molding, and can therefore be mass produced at a low cost and in large numbers. However, in designing the profile of the gear mold, compensating for the shrinkage of the gear during the molding process such that the final component has the correct geometry and dimensions represents a significant challenge. Accordingly, the present study proposes an algebraic calculation method for fine-tuning the module of the gear mold based on the actual shrinkage rate of the plastic material by progressively re-sharpening the rake surface of the hob cutter used to produce the mold. The validity of the proposed method is demonstrated by means of two illustrative examples. The results confirm that the proposed method provides an effective technique for compensating the shrinkage rate of plastic gears.