Where Delrin® AF 100 Outperforms Standard Acetal in Wear Applications

If you've spec'd standard acetal (POM) for wear-intensive parts bushings, gears, bearing surfaces, conveyor guides you already know it's a workhorse. Low moisture absorption, excellent dimensional stability, easy to machine. But in sustained dry-running, high-load, or high-cycle applications, standard acetal eventually reaches its limits. Wear rates climb. Temperatures rise. Parts need replacing sooner than planned.

That's where Delrin® AF 100 earns its premium. This isn't simply "better acetal" it's a fundamentally different tribological system, engineered specifically for the conditions where unfilled acetal falls short.

What Makes AF 100 Different

Delrin® AF 100 is a homopolymer acetal (POM-H) resin the same Delrin base that engineers trust for dimensional precision uniformly reinforced with oriented PTFE (polytetrafluoroethylene) fibers. The key word is fibers, not powder. PTFE fiber creates a self-lubricating matrix that continuously transfers a thin film of PTFE to the mating surface, reducing friction at the interface without external lubricants.

Standard acetal copolymer (POM-C) and even unfilled Delrin already have a low coefficient of friction relative to many engineering plastics. The problem is wear: under high pressure-velocity (PV) loads, without lubrication, and over thousands of cycles, acetal surfaces abrade. AF 100's PTFE fiber network dramatically suppresses this mechanism.

The Wear Advantage: How It Works in Practice

The mechanism behind AF 100's wear superiority is worth understanding. PTFE is often called "the world's most slippery solid." In fiber form, it creates a self-replenishing transfer film. As the AF 100 part slides against a mating surface (typically steel, aluminum, or another plastic), PTFE fibers deposit a molecularly thin lubricating layer on that surface. This:

• Eliminates stick-slip: Static and dynamic coefficients of friction are nearly identical, eliminating the jerky, uneven motion that accelerates wear in reciprocating or starting/stopping applications.
• Reduces surface temperature: Lower friction = less frictional heat, which in turn preserves dimensional stability and prevents thermal softening that compounds wear in dry-run scenarios.
• Extends lubrication-free service: AF 100 performs in environments where oil and grease are not acceptable food processing, cleanrooms, medical devices, and pharmaceutical equipment.

Pressure-Velocity (PV) Performance

The PV limit the product of load pressure (psi) and sliding velocity (ft/min) is the critical metric for wear component design. Exceeding the PV limit causes rapid surface degradation. Delrin® AF 100 offers a significantly higher limiting PV compared to standard acetal, particularly in dry (unlubricated) operation.

Where Emco Recommends AF 100 Over Standard Acetal

Not every application justifies the AF 100 premium. Here's where the performance gap is decisive:

When Standard Acetal Is Still the Right Call

Emco's engineering team doesn't recommend AF 100 for every acetal application. The premium is justified by performance, not novelty. Standard acetal copolymer remains the better choice when:

• Continuous lubrication is present if the mating surface is oil-bath or grease-lubricated, the PTFE advantage shrinks and standard acetal's lower cost wins.
• Maximum tensile strength is critical PTFE fibers reduce tensile strength by approximately 10%. For structural acetal components not in a wear role, unfilled grades outperform.
• Chemical resistance to hot caustic/acid environments acetal copolymer has better chemical resistance at elevated temperatures and pH extremes.
• High-volume, cost-sensitive production standard acetal is 15–25% less expensive per pound. When PV demands don't exceed the material's limit, it remains the economical choice.

Machining & Procurement Notes

Delrin® AF 100 machines comparably to unfilled Delrin sharp HSS or carbide tooling, moderate cutting speeds, and no coolant required. The PTFE fiber content creates a slightly different chip character (shorter, drier chips), which actually aids chip evacuation in deep-hole drilling. Dimensional stability post-machining is excellent.

Emco stocks Delrin® AF 100 in rod, plate, and tube forms in the dark brown color characteristic of PTFE-filled acetals. Standard 13% PTFE AF Blend is available from immediate inventory; the full-strength 20% AF 100 is available as a stocked or custom-order item depending on dimensions. Our team can also provide cut-to-size blanks to reduce material waste on complex machined components.