POM (Delrin/Acetal)

POM (Polyoxymethylene), commonly known as Delrin or Acetal, is an engineering thermoplastic renowned for its high stiffness, low friction, and excellent dimensional stability. It is often regarded as the "most machinable" plastic, bridging the gap between metals and plastics. At Jucheng Precision, we utilize this machinability to its fullest potential. Using our high-speed Haas/Mazak CNC turning and milling centers, we produce POM precision gears, bushings, and sliding components with surface finishes that rival injection molding. Unlike other plastics that warp, POM allows us to hold tight tolerances (+/- 0.02mm) consistently. Our capabilities support both the Homopolymer (Delrin) and Copolymer (Celcon) grades for automotive, consumer electronics, and industrial machinery applications.

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CNC POM Machining

Available POM (Delrin) Grades

Grade Common Name Key Characteristics Typical Applications
POM-H (Homopolymer) Delrin® 150 Higher mechanical strength, stiffness, and hardness than copolymer. Slight centerline porosity possible. Precision gears, bearings, stiff mechanical parts, check valves.
POM-C (Copolymer) Acetal / Celcon® Better chemical resistance (especially to high pH) and free of centerline porosity. Easier to machine without voids. Plumbing fittings, medical instrument handles, food processing parts.
PTFE-Filled POM Delrin® AF Blended with Teflon (PTFE) fibers. Extremely low coefficient of friction and high wear resistance. High-speed sliding bearings, bushings, conveyor wear strips.
Glass-Filled POM POM-GF Reinforced with glass fibers for increased stiffness and dimensional stability. Abrasive to tools. Structural parts requiring high rigidity and low creep.

POM Machining Capabilities

Capability Technical Description Jucheng Advantage
Precision Gear Machining Milling or hobbing high-precision plastic gears (spur, helical) directly from POM stock. We achieve high gear quality (AGMA standards) with low noise and excellent wear properties.
High-Speed Turning Rapid production of bushings and rollers using bar-fed CNC lathes. Optimized for high-volume orders (50k+ pcs/month) with extremely low unit costs.
Complex Milling 3/4/5-axis milling of intricate housings and clips with snap-fit features. POM’s stiffness allows for machining precise snap-fits that function reliably without breaking.
Burr-Free Machining Using sharp tooling and optimized paths to minimize burr formation, which can be an issue with plastics. Eliminates manual deburring for many parts, ensuring consistent edge quality and fit.

Fabrication Guidelines for POM

Clamping Sensitivity:
While stiffer than most plastics, POM can still deform. We use collets or soft jaws with controlled pressure. For flat parts, vacuum workholding is ideal to maintain flatness.

Coolant Use:
POM machines very freely, but coolant is recommended to flush chips and keep the part cool to maintain tight tolerances. Air blast is also effective for simple cuts.

Tooling:
Standard sharp HSS or Carbide tools work best. High rake angles help slice the material cleanly. Dull tools will cause heat buildup, which can lead to POM outgassing (smelling like formaldehyde).

Dimensional Stability:
POM-C (Copolymer) is preferred for parts where centerline porosity (common in thick Delrin sections) could be an issue, such as parts requiring sealing or aesthetic perfection.

Primary Application Industries

Automotive
Key Parts: Fuel system components, window lift gears, door lock actuators.
Why POM: Resistance to fuels/solvents and excellent fatigue endurance for moving parts.

Consumer Electronics
Key Parts: Zippers, clips, mechanical keyboard switches, rollers.
Why POM: Low friction (“slipperiness”) and high stiffness provide a premium tactile feel and durability.

Industrial Machinery
Key Parts: Conveyor links, bearings, wear strips, guide rails.
Why POM: Self-lubricating properties reduce the need for external grease and maintenance.

Medical Devices
Key Parts: Inhaler components, insulin pens, surgical instrument handles.
Why POM: Easy to sterilize (some grades), dimensionally stable, and resistant to cleaning agents.

Material Properties

Density 1.41 - 1.42 g/cm³
Tensile Strength 60 - 75 MPa
Impact Strength 50 - 90 J/m
Heat Deflection Temp 110 - 136 °C
Hardness 120 Rockwell R
Continuous Service Temp 90 - 100 °C
Water Absorption 0.20 - 0.25 %
Dielectric Strength 19 - 22 kV/mm
Melting Point 165 - 175 °C
Max. Part Size 2000 mm (L) x 800 mm (W) x 600 mm (H)