Custom POM Plastic Gears for Electronic Equipment

For a small gear set inside electronic equipment, purchasing the gears separately is not always enough. The larger and smaller gears need to mesh as intended, the center bores need to match their shafts, and the finished dimensions need to remain consistent from prototypes through repeat production.

The components shown here are a custom black POM spur gear set manufactured for a European electronic equipment project. Both gears are made directly from the customer's 2D drawings, with the module, tooth count, pressure angle, gear width, bore and other dimensions defined by the actual transmission design.

Because these are non-standard components, our work starts with the drawings rather than a catalog size. YS Precision provides custom plastic gear machining services for POM gears, mating gear sets, prototypes and production quantities.

Project Overview

A Mating Gear Set, Not Two Independent Parts

The most important feature in this project is the relationship between the two gears.

The larger and smaller spur gears have different diameters and tooth counts, but they operate within the same mechanism. Their geometry therefore needs to correspond with the shaft positions and transmission requirements of the electronic equipment.

Typical drawing information includes:

Module · Tooth Count · Pressure Angle · Gear Width · Bore · Critical Tolerances

We use the customer's specified data rather than estimating gear parameters from an existing sample or outside diameter.

This is one reason custom POM gears are useful when standard catalog components cannot match an existing mechanism. The gears can be manufactured around the equipment layout instead of requiring the equipment to be redesigned around an available stock gear.

Why POM Works Well for Small Mechanical Gears

POM, commonly known as acetal, is widely used for moving plastic components because it combines good dimensional stability with relatively low friction and wear resistance.

For electronic equipment, those characteristics can make POM a practical choice for compact gears, rollers and other mechanical transmission parts.

Machining POM, however, requires a different approach from machining steel or brass.

Plastic can respond to cutting heat and clamping force. Small teeth also need clean edges without excessive burrs, while relatively thin gear bodies should not be unnecessarily distorted during workholding.

The goal is not simply to reproduce the visible shape. The finished POM gear needs to maintain the dimensions required for its shaft and mating component.

Material selection should still reflect the actual operating conditions, including load, speed, temperature, lubrication and expected service life.

The Center Bore Can Decide Whether the Gear Runs Correctly

On a gear like this, the bore looks much simpler than the tooth profile—but it can be just as important in the assembly.

The teeth establish engagement between the mating gears. The bore establishes the position of the gear on its shaft.

If these two features are not correctly related to the rotational center, the mechanism may not run as intended even when the individual dimensions appear to be within tolerance.

For this reason, a drawing may call for control of characteristics such as:

Bore Diameter · Gear Width · Tooth Geometry · Runout · Concentricity

The exact inspection requirements come from the customer's drawing and the function of the component.

This is particularly relevant to a gear pair, because dimensional variation in either part can influence the final engagement.

How We Approach a Custom POM Gear Set

Production starts by reviewing both the gear geometry and the shaft features.

A typical route may be:

POM Material → Blank Preparation → Bore & Reference Machining → Gear Tooth Machining → Deburring → Dimensional Inspection

The actual method depends on the gear size, tooth geometry, thickness, bore design, tolerances and order quantity.

For a mating set, we also consider the relationship between the larger and smaller gears instead of viewing each drawing in isolation.

This matters during both first-part production and repeat orders. Once the machining setup is established, the objective is to maintain the drawing-defined characteristics consistently across the required quantity.

When Machining Makes More Sense Than Molding

For product development and lower production volumes, machining offers an important advantage: no injection mold is required before the design has been proven.

A customer developing new electronic equipment may first need only a limited number of prototype gears for:

Fit Check · Shaft Assembly · Gear Engagement · Functional Testing

If testing leads to a change in the bore, thickness or other dimensions, the drawing can be revised before the next batch is machined.

This makes prototype plastic gear machining useful during engineering validation.

After the design is confirmed, the same project can move into small-batch or repeat production. If demand later increases substantially, the annual quantity and component geometry can be reviewed again to determine whether continued machining or injection molding provides the more suitable production route.

The manufacturing method should follow the stage of the product—not the other way around.

What Matters When the Same Gear Is Ordered Again

For a production manager, an acceptable first sample solves only the first part of the problem.

The next question is whether the same gear can be supplied consistently when another batch is required.

For repeat plastic gear production, inspection can focus on the features that affect assembly and operation rather than only general outside dimensions.

Depending on the drawing, these may include:

• center bore diameter;
• gear thickness;
• drawing-defined tooth characteristics;
• runout or concentricity where specified;
• burr and edge condition.

For mating gears, both components also need to remain consistent with the transmission design.

This is why we prefer to identify the functional dimensions from the customer's drawing before production rather than applying the same generic inspection checklist to every plastic part.

Custom Plastic Gear Machining from Your Drawings

YS Precision manufactures custom plastic gears for electronic equipment, instruments and mechanical assemblies.

For POM gear projects, our manufacturing scope can include:

Gear Blank Machining · Precision Bore Machining · Plastic Gear Cutting · POM Gear Machining · Deburring · Dimensional Inspection

We can support individual gears as well as mating gear sets with non-standard dimensions.

The service is particularly suitable for customers who need prototype plastic gears, small-batch quantities or repeat production without being limited to standard catalog sizes.

Send Us Your Gear Drawing for Review

For a new POM gear project, the best starting point is the complete 2D engineering drawing. A 3D CAD model can also be provided where available.

Please include the relevant:

Material · Module · Tooth Count · Pressure Angle · Gear Width · Bore · Critical Tolerances · Mating Gear Information · Quantity

If the components operate as a gear set, providing both drawings helps us understand their relationship within the mechanism before quotation.