POK Material Guide for Dynamic Sealing & Sliding Parts | Grade Selection, Injection Molding & Applications

1. Introduction: Why POK Outperforms POM & PA for Sealing Components

Aliphatic Polyketone (POK / POKETONE) is a high-performance thermoplastic widely recognized as an upgraded alternative to POM and PA for dynamic sealing and sliding components. Compared with traditional engineering plastics, POK features ultra-low water absorption, excellent hydrolysis resistance, outstanding oil/grease resistance, low creep, high elastic recovery, low friction, and minimal stick-slip behavior.

These unique mechanical and tribological properties make POK the ideal material for hydraulic systems, fluid control equipment, and precision moving parts that require long-cycle dynamic operation and stable sealing performance.

Most importantly, all qualified POK grades and custom-modified POK compounds are fully injectable, supporting high-precision injection molding for mass production, as well as machining from extruded rods for prototype samples.

2. Core Material Requirements for High-End Dynamic Sealing

For hydraulic dynamic sealing and reciprocating sliding parts, the industry’s strict technical specifications require balanced ductility, rigidity, and friction performance:

• Hardness: 73–79 Shore D

• Tensile Strength: ≥ 60 MPa

• Elongation at Break: ≥ 250%–300% (core indicator for elastic recovery and crack resistance)

• Excellent elastic recovery and low creep

• Low friction, ultra-low stick-slip, and high wear resistance

• Superior resistance to hydraulic oil, grease, and hydrolysis

• Low water absorption for stable dimensional accuracy

• Unreinforced formula (no glass fiber) to avoid scratching mating surfaces

3. POK Grade Comparison & Correct Selection Logic

Different POK grades have huge performance differences. Many failed sealing tests result from incorrect grade substitution. Below is the official Hyosung POKETONE grade guide for sealing and sliding applications:

3.1 M630 / M630A (Best for Dynamic Sealing)

• Features: High toughness, ultra-high elongation, low creep, stable elasticity, natural hardness within 73–79 Shore D

• Application: The most suitable base resin for custom-modified dynamic sealing parts

• Recommended Formula: M630 base + 5–8% PTFE + 1–1.5% silicone lubricant

• Advantage: Fully meets high elongation and elastic recovery requirements, eliminates stick-slip, and ensures long-term sealing stability

• Process: 100% injection moldable and extrudable

3.2 M33AT2E (Not Suitable for Dynamic Sealing)

• Features: Pre-added PTFE + silicone, good wear resistance and noise reduction

• Limitation: Hardness up to 86 Shore D, tensile strength only 50 MPa, elongation at break ~40% (far below sealing requirements)

• Applicable scenarios: Static bushings, ordinary gears, general wear-resistant parts

• Risk: Brittle, poor resilience, easy micro-cracking under reciprocating dynamic load, causing sealing failure

3.3 M330A / M33AS1A (General Wear-Grade)

• Balanced mechanical properties, silicone-lubricated version for slight friction reduction

• Suitable for light-load sliding parts, common valve components, non-critical wear parts

3.4 M230A / M930A (High-Flow Injection Grade)

• High fluidity, perfect for thin-walled and complex structural parts

• Mainly used for plastic housings, connectors, and non-friction structural components

4. Why Custom Modified M630 POK Is the Only Qualified Solution

Off-the-shelf lubricated POK like M33AT2E only focuses on wear resistance but sacrifices toughness and elasticity. For dynamic sealing, elongation and elastic recovery are more critical than pure wear resistance.

Custom compounded M630 + PTFE + silicone perfectly balances toughness, hardness, friction performance, and dimensional stability:

• PTFE reduces friction and improves wear resistance

• Silicone eliminates stick-slip and ensures smooth sliding

• M630 base provides high elongation and low creep for long-term dynamic sealing

Note: Twin-screw pre-compounding is strongly recommended instead of simple dry blending, to avoid uneven additive dispersion and unstable batch performance.

5. Injection Molding Feasibility & Process Tips

All custom modified POK compounds are standard thermoplastic pellets, fully suitable for precision injection molding.

• Drying: 80℃ for 3–4 hours

• Barrel temperature: 230–245℃

• Processing advantage: Stable fluidity, low shrinkage, high dimensional consistency

• Production mode: Mass injection molding for formal production; rod machining for small-batch prototypes

6. Common Industrial Injection Molding Applications of POK

6.1 Hydraulic & Fluid Control System (Core Scenario)

Dynamic sealing rings, valve sliding sleeves, guide rings, plunger components, hydraulic valve wear parts, and reciprocating sliding seals for construction machinery and agricultural equipment.

6.2 Automotive Fluid & Transmission Parts

Cooling system valve parts, fuel system sliding components, brake guide sleeves, HVAC water valve seals, and new energy thermal management wear parts.

6.3 Automation & Precision Equipment

Oil-free sliding blocks, cylinder guide bushings, pump vanes, low-noise moving parts requiring ultra-low stick-slip performance.

6.4 Water Treatment & Home Appliance Components

Water pump sealing parts, water meter valve cores, and hydrolysis-resistant fluid components working in long-term wet environments.

6.5 General Replacement for POM/PA Parts

Silent gears, rollers, elastic buckles, quick-connect wear rings, and durable structural wear parts.

7. Summary & Selection Rules

• Dynamic sealing & reciprocating sliding: Custom modified M630 + PTFE + silicone (only qualified solution)

• Static wear parts & general gears: M33AT2E, M33AS1A

• Thin-walled complex structures: M230A / M930A high-flow grades

• Never judge POK performance only by wear resistance. Dynamic sealing requires high elongation, elasticity, and low creep priority.

• All professional-grade modified POK materials support stable and high-precision injection molding for industrial mass production.