Delrin AF (PTFE-filled Acetal)

Overview

Delrin AF is DuPont's trade name for PTFE-filled acetal (POM) — a bearing-grade compound produced by blending PTFE fibres into the acetal matrix. The PTFE filler reduces the coefficient of friction and improves wear resistance in sliding contact applications compared with unfilled acetal. Delrin AF retains acetal's key strengths — precise machinability, dimensional stability, low moisture absorption, and chemical resistance — while improving dry-running bearing performance. It is used for bushings, thrust washers, slide rails, and mechanical components that require dry running or minimal lubrication. The standard grade is a white/off-white material; it is available in rod and sheet form.

Working properties

• Reduced friction vs unfilled acetal

  The PTFE filler acts as an internal lubricant, lowering the friction coefficient of the material against mating surfaces. This reduces running temperatures, extends wear life, and allows dry running in applications where liquid lubrication is impractical.

• Wear resistance

  Delrin AF has improved PV (pressure × velocity) capability compared with unfilled acetal. It is appropriate for moderate-load, moderate-speed bushing and bearing applications that would cause premature wear in standard acetal or POM.

• Machinability

  Delrin AF machines very similarly to unfilled acetal — clean cuts, tight tolerances, and good surface finish. The PTFE content does not significantly affect machinability. Standard tooling used for acetal is appropriate.

• Dimensional stability

  Like standard acetal, Delrin AF has very low moisture absorption and good dimensional stability. Machined components hold their tolerances well across varying humidity conditions — an advantage over nylon-based bearing grades.

• Load and speed limits

  Delrin AF is suitable for moderate load and speed conditions. For heavy loads, high speeds, or elevated temperatures, dedicated bearing grades such as Rulon or Turcite, or filled PEEK grades, should be considered.

Typical uses

• Dry-running bushings and sleeve bearings in food, packaging, and general machinery
• Thrust washers and wear pads in mechanical equipment
• Slide rails, guide strips, and sliding contact surfaces
• Cam followers, rollers, and low-load bearing components
• Components requiring minimal or no lubrication for maintenance reduction

Things to confirm before ordering

• PTFE content — different grades have different PTFE levels (typically 15–20%); confirm grade specification if a specific PTFE content is required.
• Load and speed — confirm the PV (pressure × velocity) conditions for your application to verify suitability.
• Mating material — performance in dry running depends on the counterface material; hardened steel and stainless steel are common counterfaces.
• Form and size — confirm rod diameter or sheet thickness and dimensions required.

How does Delrin AF (PTFE-filled Acetal) compare?

• Standard Acetal (POM)

  Standard acetal is more economical and appropriate for most structural and general-purpose applications. Delrin AF is chosen specifically when dry-running friction or wear life must be improved beyond what unfilled acetal provides.

• Nylon (PA)

  Nylon has comparable bearing properties but higher moisture absorption, which causes dimensional change. Delrin AF is preferred where dimensional stability in varying humidity is important.