Wear-Resistant and Low-Friction POM Selection Guide

Wear Resistance and Low Friction Are Not the Same Requirement

Wear resistance describes how well a material resists surface loss, scoring, deformation, or other damage during repeated contact. Low friction describes the resistance generated when one surface begins or continues to move against another. These properties are related, but they should not be treated as interchangeable.

A low-friction material may reduce operating force without necessarily providing the longest wear life under high load. Conversely, a highly wear-resistant material may maintain its dimensions over repeated cycles but still produce more friction, noise, or heat than the application allows.

The distinction becomes important in practical component selection. A bushing may need long service life with minimal dimensional change. A slider may require smooth initial movement and limited stick-slip. A gear may need stable tooth geometry, acceptable noise, and controlled wear on both surfaces. A valve moving part may need predictable movement after long periods of inactivity.

• Is the molded POM part wearing too quickly?
• Is the mating component being damaged?
• Is the movement force too high or inconsistent?
• Is the mechanism producing noise, vibration, or stick-slip?
• Is external lubrication unavailable or undesirable?
• Is dimensional change affecting positioning or sealing?

Review Load, Speed, and Movement Pattern Together

Load should be reviewed at the contact surface, not only as the total force applied to the component. A small contact area can create high local pressure even when the overall load appears moderate. Edge contact, misalignment, sharp geometry, and uneven assembly can further increase local stress.

Speed also influences wear and friction behavior. Slow movement can create stick-slip or high breakaway force, while faster movement may generate frictional heat. The effect of speed depends on the load, mating surface, lubrication condition, and movement duration.

Continuous rotation, repeated oscillation, short sliding strokes, and occasional actuation do not produce the same wear conditions. A roller running continuously may require a different material direction from a valve component that remains stationary for long periods and then moves suddenly.

For relatively demanding wear conditions, Taiyi POM EDM-111 may be reviewed as a high wear-resistant direction. POM EMS162, based on a MoS2-filled high wear-resistant direction, may also be considered where the selected additive system matches the contact conditions. POM ENM1040 provides another option based on a special wear-resistant additive direction.

Mating Material and Surface Finish Can Change the Result

A POM component does not wear independently. Its behavior is strongly affected by the material and surface condition of the part it contacts. Steel, aluminum, brass, coated metal, rubber, POM, PA, and other engineering plastics may each produce different friction and wear results.

Surface finish is equally important. A rough metal surface can act as an abrasive and remove material from the polymer. A damaged, corroded, poorly machined, or contaminated mating surface can cause rapid wear even when a suitable modified POM has been selected.

Hard fillers or reinforcing fibers should also be reviewed for their possible effect on the counterpart. A reinforced POM may improve stiffness and dimensional control but could increase wear on a softer mating surface.

For applications requiring both reinforcement and lubrication, POM EGH20-TF may be considered as a PTFE and glass fiber direction. Aramid fiber or aramid powder filled POM directions may also be reviewed where wear behavior, mechanical support, or a particular contact balance is required.

Selecting PTFE, MoS2, Silicone Oil, or Other Wear Additive Directions

Different wear and lubrication additives influence POM through different mechanisms. They should be selected according to the operating system rather than treated as equivalent methods of achieving self-lubrication.

PTFE-filled POM is commonly considered where reduced friction, smoother sliding, or lower operating force is required. Taiyi POM EPTL402 represents a PTFE-filled direction. POM EGH20-TF combines PTFE with glass fiber and may be considered where the application requires a balance of lubrication and additional stiffness.

MoS2-filled POM, represented by POM EMS162, may be considered for high-wear applications where its solid-lubricant system is appropriate. POM ESO102 is a silicone-oil-modified, high-lubricity direction. Consider it when smooth movement, lower friction, less operating force, or improved running feel matters.

POM ENM1040 uses a special wear-resistant additive direction, while POM EDM-111 is positioned as a high wear-resistant direction. These options may be relevant where a customer requires a different balance from conventional PTFE-, MoS2-, or silicone-modified systems.

• Required wear life
• Static and dynamic friction
• Mechanical strength and stiffness
• Dimensional tolerance
• Counterpart material and hardness
• Dry or lubricated service
• Noise and movement quality
• Surface and secondary-process requirements
• Production stability and moldability

Lubrication, Noise, and Stick-Slip Should Be Evaluated Separately

The first question regarding lubrication is whether the component operates dry, with grease or oil, or with occasional contact from process fluids. A material that performs well in dry sliding may not provide the same advantage in an externally lubricated system.

Where external lubrication is not practical, an internally lubricated POM direction may be considered. However, self-lubricating should not be interpreted as meaning that friction and wear are eliminated. The contact system still depends on load, speed, geometry, temperature, mating material, and surface condition.

Noise is also not controlled by friction alone. Gear noise, squeaking, chatter, and vibration may be influenced by dimensional accuracy, stiffness, tooth profile, assembly clearance, surface finish, resonance, lubrication, and molding variation.

Stick-slip occurs when the force required to begin movement is significantly different from the force required to continue movement. It is often important in sliders, guides, adjustment mechanisms, valve controls, seats, and slow-moving components.

Counterpart Wear Can Be More Important Than POM Wear

Material evaluation often focuses only on the weight loss or dimensional change of the POM component. This can produce an incomplete conclusion. The mating surface may experience polishing, scratching, coating removal, abrasion, or dimensional damage even when the POM part appears acceptable.

This is especially important when POM runs against soft metals, plated components, painted surfaces, sealing elements, or another molded polymer. Reinforcing fibers and some functional fillers may alter the wear mechanism of the contact pair.

A successful tribological material should therefore be evaluated as part of a two-surface system. Tests should inspect both the POM component and the counterpart. Engineers may need to review dimensional change, wear debris, surface damage, operating force, temperature rise, noise, and the stability of the contact area.

For gears and similar paired components, the material combination should be considered together. Using the same material on both parts is not always the best solution. Different hardness, surface conditions, geometries, or modification systems may provide a more stable contact pair, but the final combination should be tested.

Why Laboratory Wear and Friction Data Are Not Enough

Laboratory values are useful for preliminary comparison, but tribological results are highly dependent on the test method. A coefficient of friction or wear rate measured under one set of conditions may not predict performance in another system.

Even data from two suppliers may not be directly comparable when the test methods, specimen preparation, conditioning, or counterpart surfaces are different. A lower reported friction value should not automatically be interpreted as better component performance.

Molded parts introduce additional variables that standard laboratory specimens may not represent. These include gate position, weld lines, shrinkage, orientation of fibers or fillers, residual stress, surface replication, part warpage, and dimensional tolerance.

Molded-part trials should therefore reproduce the real assembly as closely as possible. Testing should use the actual counterpart material, representative load and speed, expected lubrication condition, and a meaningful number of operating cycles.

• Test specimen geometry
• Counterpart material and hardness
• Surface roughness
• Contact pressure
• Sliding speed
• Movement direction
• Test duration
• Temperature and humidity
• Dry or lubricated conditions
• Initial running-in period

What to Send Before Grade Recommendation

A grade recommendation should not be based only on the statement that the customer needs wear-resistant POM or low-friction POM. More complete application information helps distinguish between EDM-111, EGH20-TF, EMS162, ENM1040, EPTL402, ESO102, aramid-filled directions, or another material approach.

Use this information to choose a material direction. Then review the applicable TDS, mold representative parts, and test them under actual or closely simulated operating conditions.

• Part name, drawing, photo, and main function
• Current material or current grade
• Current failure mode or performance problem
• Type of movement: sliding, rotation, oscillation, rolling, or intermittent actuation
• Load, contact pressure, speed, sliding distance, and duty cycle
• Expected service life or number of cycles
• Mating material, hardness, coating, and surface finish
• Dry operation or lubricant type
• Operating temperature and environmental conditions
• Noise, stick-slip, or operating-force requirements
• Existing TDS, test reports, wear samples, or failed components