Custom plastic helical gears

Custom plastic gear manufacturers

We are capable of manufacturing and supplying all kinds of custom-designed plastic gears including spur and helical gears, worm gears, bevel gears, and racks of small and large sizes. We have the engineering capabilities of designing gears, choosing the right parameters and materials for gears.

Here is an example of our recent job.

injection mold plastic helical gear close view

Main gear parameters

Normal module (mn)/transvese module (mt)mn=0.74mm / mt=0.7428mm
Teeth number (z)z=82
Helix angle (β)β=5°
Reference diameter (d)d=60.91mm
Tip diameter (da)da=62.17mm
Profile shift coefficient (x)x=-0.15

Plastic helical gears have many advantages over spur gears, including reduced impact and noise, running more smoothly, more load capacity and longer product life.

Plastic material is acetal (POM)

This is the most used plastic material for plastic gears, because it has good dimensional stability, strength, and ductility. It is also humid and corrosion-resistant.

Mold cost: $2,500

  • Cavity number: 1
  • Mold material: 718H
  • Lead time: 45 days

We use high-end machines to produce the mold

This is necessary for producing the molds for precision plastic parts like gears. It means higher machining cost, better accuracy, and less manual work after the workpieces are taken off the machine.

We used slow speed EDM wire cutting (also called as WEDM-LS) to produce the teeth profile, with one coarse cut plus four finishing cut, this way we can ensure the accuracy and smoothness of machined finish. As a result, we do not need to manually polish the surface to the required smoothness.

EDM cut teeth profile for plastic gear

As a matter of fact, it is always better to rely more on machine accuracy and reduce manual work, because machines can always do better jobs than human hands. However, we still have to balance between the cost and accuracy, so we can get the best price/quality output.

You may also notice that for plastic helical gears, the direction of teeth is not vertical to the end surface. This can also be properly handled by the EDM wire cutting machine.

Proper mold design is critical for plastic gears

As you can see from the pictures, we designed 3 gates which are radial symmetrical to the sprue. This is a typical mold design for gears to ensure even flow of material, and pressure, temperature distribution. In order to get the required accuracy, we need to control the pressure and temperature precisely.

We keep the mold temperature at around 140℃,and make the gate a bit wider to ensure the quick flow of material. By doing thisso, the plastic helical gears are produced with good dimensional stability, and the weld lines are minimized.

3 gates on the injection mold for gears

Another recommended mold design is one gate at the center of the gear, but this is only for plastic gears without a hole in the center.

Other earlier jobs of plastic helical gears

Here are a few pictures:

other plastic helical gears other plastic helical gear 2