Overview
POM (polyoxymethylene, also known as acetal or Delrin) bearing sleeves are low-friction, dimensionally stable plain bearings used in pumps, appliances, automotive mechanisms, and industrial machinery. Acetal’s combination of stiffness, fatigue resistance, low moisture absorption, and easy machining makes it the workhorse polymer for unlubricated bearing and bushing applications.
ORRO Manufacturing machines POM bearing sleeves to precise bore and outside-diameter tolerances, holding the concentricity needed for smooth rotation. We can machine grooves, flanges, and lubrication pockets, and match sleeves to your shaft and housing fits for reliable press-fit assembly.
Material Properties
| Property | POM (Acetal Homopolymer) |
|---|---|
| Density (g/cm³) | 1.41 - 1.42 |
| Tensile Strength (MPa) | 60 - 70 |
| Flexural Modulus (GPa) | 2.5 - 3.0 |
| Hardness (Rockwell M) | 80 - 88 |
| Max Continuous Temperature (°C) | 90 - 100 |
| Coefficient of Friction (vs. steel) | 0.20 - 0.35 |
| Limiting PV (MPa·m/s) | 0.10 - 0.15 |
| Water Absorption (%) | 0.2 - 0.5 |
Key Advantages
- Low, Consistent Friction: Smooth running against steel shafts with minimal lubrication.
- Dimensional Stability: Very low moisture absorption keeps fits accurate in humid or wet service.
- High Fatigue Endurance: Withstands millions of load cycles in oscillating and rotating duty.
- Good Stiffness and Strength: Stiffer than nylon or PTFE for load-bearing bushings.
- Excellent Machinability: Machines to fine tolerances with a clean finish.
- Wear Resistant: Long service life in dry and lubricated bearing applications.
Typical Applications
Pumps and Small Motors
Bearing sleeves and thrust faces in pumps, fans, and fractional-horsepower motors.
Automotive and Appliance Mechanisms
Door latches, window mechanisms, and small actuators that need quiet, maintenance-free bearings.
Industrial Automation
Bushings and sleeves in conveyors, packaging machinery, and linear actuators.
Machining Capabilities
| Parameter | Capability |
|---|---|
| Tolerance | ±0.02 mm (bore), ±0.05 mm (outside diameter) |
| Surface Finish | Ra 0.8 - 1.6 μm |
| Size Range | 5 mm to 200 mm diameter |
| Key Processes | CNC turning, boring, milling, grooving |
Application Case
Pump bearing sleeve, POM — A pump manufacturer needed maintenance-free bearing sleeves to replace oil-impregnated bronze bushings in a water pump. ORRO machined POM sleeves with a ±0.02 mm bore and a machined lubrication groove, supplying 25,000 units in 20 days. The acetal sleeves ran quieter, eliminated oil staining, and reduced cost by 40%.
