In the last few weeks we have talked about the erroneous association between a high level of noise and the incorrect or poor quality of gears and the noise causes of very small gear motors, subjects on which there is a great deal to comment. It is from one of the comments I read recently that I draw inspiration for today’s post. The person that wrote it suggested
using plastic gears to reduce the noise of a transmission.
Good point! And this is the starting point for a broader discussion.
Even though my life spent in a mechanical workshop has guided me towards a predilection for metallic materials, I can’t – as a designer – ignore the huge evolution of plastic materials in recent years. Today we have plastics that are able to withstand continuous use at temperatures of 300°C, with good dimensional stability, characterized by excellent resistance to chemical aggressions and that are also accompanied by the FDA (Food and Drug Administration) approval for food contact or that even offer biocompatibility, etc.
Experienced technicians know well that gears made of plastic have the ability to dampen noise and to reduce the transmission of vibrations at costs that are affordable (production via injection moulding for consistent batches is in fact very economical). However, the use of components of such materials should not, in my view, be taken into account solely for economic reasons but also and above all to accompany traditional metal constructions with technical solutions capable of solving a large number of other issues (obviously where the forces involved so permit).
I think it is important to add that opting for plastic materials instead of metal ones often doesn’t result in cost reductions, quite the opposite in fact. It is not uncommon to find yourself in the opposite situation, given the quality and the performance level of certain products on the market today.
It goes without saying then that it is not a consideration that can be applied to all types of plastics such as normal amorphous or thermoplastic polymers but rather is valid for advanced technical products such as VESPEL®, PEEK® and for others.
The high quality that a gear can reach depends only to a very small extent on the type of material used and more so on the construction technology adopted. At MICROingranaggi, for example, we produce plastic gears using tool machines that allow the achievement of very high levels of quality, very similar to those that characterize metal components.
This is very different from the case in which these components are made by injection moulding for large series of products where, in general, more modest or even, in many cases, very low levels of quality are achieved.
