Nowadays, the progress in polymer materials and injection molding processing has enabled a drastic expansion of plastic gear applications. They are used not only for lightly loaded motion transmissions, but also in moderately loaded power drives in automotive, agriculture, medical, robotics, and many other industries.
The wear behavior of polymer gears made of five different materials has been investigated using an existing polymer gear test rig. Step loading tests at a constant speed of 1,000 rpm were performed. Significant differences in failure modes and performance have been observed for the five polymer gear materials for gear engagements of gears, with the same material as each other.
The aim of the study was to apply such a specialized tooth contact analysis method, well-used within the steel gear community, to a polymer gear application to assess what modifications need be made to these models for them to be applicable to polymer gears.
Plastic gears are everywhere
today - throughout your car, at
the oceans' lowest depths, in deep
space. The question, when is a
metal gear a candidate for plastic
conversion, can be addressed in
three words, i.e. what's the application?
In the hypercompetitive race to increase automobile efficiency,
Metaldyne has been developing its balance shaft module line with Victrex
PEEK polymer in place of metal gears.
The collaborative product development
resulted in significant reductions in
inertia, weight and power consumption,
as well as improvement in noise, vibration and harshness (NVH) performance.
Curved face width (CFW) spur gears are not popular in the gear industry. But these non-metallic gears have advantages over standard spur gears: higher contact ratio, higher tooth stiffness, and lower contact and bending stresses.
There is an increasing significance of screw helical and worm gears that combine use of steel and plastics. This is shown by diverse and continuously rising use in the automotive and household appliance
industries. The increasing requirements for such gears can be
explained by the advantageous qualities of such a material combination in comparison with that of the traditional steel/bronze pairing.
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.