PTFE vs POM (Polyacetal) Sliding Pads — Chemical Resistance Guide

In chemical processing, pump manufacturing, and heavy industrial machinery, sliding pads are subjected to some of the harshest environments imaginable. The choice between PTFE (Polytetrafluoroethylene) and POM (Polyoxymethylene/Acetal) often dictates whether a component will last for years or fail within weeks. This guide provides a comprehensive technical comparison of these two materials, with a specific focus on chemical compatibility and tribological performance.

• 1. Sliding pad applications in harsh environments
• 2. PTFE properties: Friction and Chemical Inertness
• 3. POM properties: Rigidity and Creep Resistance
• 4. Chemical compatibility table by class
• 5. Cost vs performance trade-off
• 6. Hybrid installations: POM body + PTFE wear face
• 7. Manufacturing standards and Quality Assurance

Sliding pads, also known as wear pads or bearing blocks, are used to support moving loads while minimizing friction and wear. In industrial settings, they are found in:

• Chemical Processing: Tank supports, agitator bearings, and valve seats where exposure to acids or bases is constant.
• Pump Manufacturing: Shaft bushings and thrust washers in centrifugal pumps handling corrosive fluids.
• Marine Engineering: Rudder bearings and hatch cover pads exposed to salt water and UV radiation.
• Oil & Gas: Pipe supports and skid-mounted equipment pads requiring high load capacity and weather resistance.
• Conveyor Systems: Guide rails and slider beds in bottling or food processing where frequent wash-downs occur.

PTFE (known widely by the brand name Teflon™) is the gold standard for chemical inertness. Its carbon-fluorine bond is one of the strongest in organic chemistry, making it virtually unreactive.

Key Engineering Specifications for PTFE:

• Coefficient of Friction (COF): 0.04 to 0.10. It is the slipperiest solid material known to man.
• Service Temperature: -200°C to +260°C. PTFE maintains its properties in cryogenic temperatures and extreme heat.
• Chemical Resistance: Resists almost all known chemicals, including aqua regia and hydrofluoric acid. Only molten alkali metals and certain fluorine compounds can attack it.
• Water Absorption: <0.01%. Completely waterproof and non-swelling.
• Dielectric Strength: Excellent electrical insulator, even at high frequencies.

Limitations: PTFE is relatively soft and prone to "cold flow" or creep under sustained high loads. It is also difficult to machine to extremely tight tolerances due to its thermal expansion and flexibility.

POM (Polyacetal), often referred to by the brand Delrin® (homopolymer) or simply Acetal (copolymer), is a high-performance thermoplastic known for its metal-like properties.

Key Engineering Specifications for POM:

• Tensile Strength: 60 - 70 MPa. Significantly stronger and more rigid than PTFE.
• Creep Resistance: Excellent. POM holds its shape under sustained pressure, making it ideal for structural sliding pads.
• Service Temperature: -40°C to +100°C (up to 140°C for short periods).
• Coefficient of Friction (COF): 0.20 to 0.30. While higher than PTFE, it is still very low for a structural plastic.
• Machinability: Exceptional. POM produces clean, crisp chips and can be machined to ±0.02mm tolerances on standard CNC equipment.

Limitations: POM is sensitive to strong acids (pH < 4) and strong oxidizing agents. Homopolymer POM is also susceptible to hydrolysis in hot water or steam over 80°C.

The following table provides a high-level comparison of how PTFE and POM react to various chemical classes. Ratings: E (Excellent), G (Good), P (Poor/Not Recommended).

Choosing the right material is an exercise in balancing engineering requirements with project budgets. At JSLT, we provide both raw materials and finished CNC parts, allowing us to offer the most cost-effective path forward.

• PTFE Cost: Higher initial material cost. However, its longevity in extreme chemical environments often results in a lower Total Cost of Ownership (TCO) due to reduced downtime.
• POM Cost: More economical for large-volume parts. Its high machinability reduces labor costs during the CNC phase.
• Lead Times: We maintain a large stock of both POM and PTFE sheets/rods, allowing us to offer Quote in 24h and fast shipping on standard sizes.

If your application involves moderate temperatures (<100°C) and no strong acids, POM is almost always the better value choice. If there is any doubt about chemical exposure or temperature spikes, PTFE is the "safe" choice.

For advanced engineering challenges, JSLT often recommends hybrid sliding pads. This design combines the structural rigidity of POM with the low-friction/chemical resistance of PTFE.

How it works:

1. POM Body: Provides the structural support, mounting points, and creep resistance. It is CNC machined with a recessed pocket.
2. PTFE Wear Face: A thinner PTFE sheet (or glass-filled PTFE) is inserted into the POM pocket.
3. Mechanical Retention: The PTFE is held in place by counter-bored fasteners or a dovetail fit. This prevents the PTFE from "creeping" out from under the load.

This hybrid approach allows engineers to achieve COF values of ~0.05 while maintaining the dimensional stability of a metal-like plastic. It also significantly reduces material costs compared to a solid PTFE block.

JSLT Engineering Plastics is committed to delivering precision components that meet international standards. Our facility in Dezhou is SGS / FDA / RoHS verified certified, and we follow strict QA protocols for all sliding pad production.

• Material Certification: Every batch of PTFE and POM is verified for density, tensile strength, and purity.
• Surface Finish: We can achieve surface roughness as low as Ra 0.4 μm on POM and Ra 0.8 μm on PTFE through specialized CNC tooling.
• Low MOQ: We support both large industrial projects and small maintenance needs with an MOQ from 1 piece.
• Global Logistics: Based in Shandong, we offer FOB Qingdao pricing and can provide CIF quotes to any major global port.

Our engineering team is available to review your chemical compatibility charts and recommend the exact polymer grade (Virgin, Glass-filled, Carbon-filled, or MoS2-filled) for your specific sliding pad application.

Technical Assistance Available

Email Claire for chemical compatibility charts, material samples, and FOB Qingdao quotations.