As plastic technology advances, so do the applications for gears made from this versatile material. Today, well-designed plastic gears can outperform metal gears in a wide range of situations that would have been impossible with metals only a few years ago. However, some of these advantages are offset by design pitfalls unique to plastics. This article outlines the most common ones and offers some tips that will help avoid them.
The main plastic materials used to make gears are acetal and nylon. These are available in molded and machined forms. The choice between molded and machined gears will depend on factors such as tolerances, tooth geometry and load capacity. In general, molded gears are more cost effective for most applications while machined gears provide greater precision.
Both acetal and nylon are highly resistant to corrosion by most chemicals. This property, combined with their low moisture absorption and self-lubricating properties, helps extend the life of plastic gears. This ability to resist corrosion helps reduce maintenance costs and downtime.
In addition, despite their hardness, most plastics are much less brittle than metals. This gives them a higher margin of safety for use in machinery and equipment that may experience high levels of shock and vibration. While metals can withstand some level of vibration, it is not uncommon for this type of stress to cause the gears to crack and fail.
Plastics, on the other hand, have the ability to absorb vibration and energy while still functioning properly. This allows them to perform more reliably than metal gears and also helps prevent damage to other parts of the equipment or structure in which they are installed.
Because of their light weight, plastics do not put as much stress on other gears and components in which they are installed. This reduces noise and wear and tear and extends the lifespan of the other gears in the system. In turn, this can also reduce maintenance and repair costs and downtime.
Another benefit of plastic gears is that they can often be sized with smaller teeth than metal gears, which can save on both materials and cost. This can also reduce weight, which can further enhance performance and efficiency and also decrease the amount of heat generated during operation.
While some early adventures with plastic gears were hampered by quality problems and failures, today’s well-designed gears made from these versatile materials routinely outperform their metal counterparts. This is due to advancements in both the materials and the manufacturing processes that go into making them.
For example, modern thermoplastics, such as those produced by Stagnoli, have superior chemical and temperature resistance. These plastics are made from petroleum byproducts that manufacturers would otherwise have discarded as waste. In addition, they have a very low moisture absorption rate and are able to withstand high heat while still maintaining their shape and function. This makes them an excellent choice for applications where there is a lot of exposure to water and other moisture-based chemicals.