POM Polyoxymethylene Acetal Delrin Rod Bar 330mm / 13 inch Long Dia. 3mm~85mm #

Engineering Plastics · POM / Acetal / Delrin · Round Rod · 330mm Length · Custom Diameter

What Is This POM Acetal Rod?

POM (Polyoxymethylene) — also sold under the trade names Delrin (DuPont) and Acetal — is a high-stiffness, low-friction engineering thermoplastic. This listing is for a round rod stock, 330mm (approximately 13 inches) long, available in diameters from 3mm up to 85mm, in black or white. POM machines beautifully on a lathe or mill: it cuts cleanly, holds tight tolerances, and produces a smooth surface finish without the gummy behavior of nylon or the chipping tendency of acrylic.

In short: The rod you machine into bushings, rollers, gears, and insulators when you need a plastic that is dimensionally stable, self-lubricating, and does not absorb water like nylon.

Why Choose POM Over Nylon or PTFE for Machined Parts

1. Dimensionally Stable — No Water Swell

Nylon (PA6/PA66) absorbs moisture from the air — up to 2-3% by weight — which causes it to swell and change dimensions. If you machine a tight-tolerance bearing from nylon in winter, it may seize up in summer humidity. POM absorbs negligible moisture and stays dimensionally stable year-round. This is why precision bushings, valve seats, and pump impellers are made from acetal, not nylon.

2. Self-Lubricating and Low Friction

POM has a naturally slippery surface — its coefficient of friction against steel is around 0.2 (dry), similar to PTFE but with much better wear resistance. This makes it an excellent material for plain bearings, slide blocks, cam followers, and gear teeth where you want low friction without external lubrication.

3. Machines Like Brass

If you have experience machining metals, POM will feel familiar — it produces clean, curled chips rather than the stringy swarf of nylon or the dust of acrylic. It can be turned, milled, drilled, tapped, and reamed with standard HSS tooling at speeds similar to aluminum. Use sharp tools with positive rake and you will get a glossy finish without polishing.

Key Specifications

Specific grade (homopolymer vs copolymer), density, tensile strength, and hardness — verify from supplier datasheet. This is general-purpose POM rod stock; if you need FDA-compliant or UV-stabilized grades, contact us before ordering.

Typical Machined Parts Made from This Rod

• Plain Bearings & Bushings: Self-lubricating sleeve bearings for low-speed shafts, conveyor rollers, and hinge pins
• Spur Gears & Worm Wheels: Light-duty power transmission gears that run quietly against metal gears without lubrication
• Valve Seats & Seals: Chemical-resistant valve components for water, mild acids, and alcohol-based fluids
• Insulators & Standoffs: Electrical isolation in assemblies where metal fasteners would cause a short
• Jigs & Fixtures: Machining fixtures that will not mar softer workpiece surfaces
• Pump Impellers: Lightweight, corrosion-resistant impellers for small centrifugal pumps

Frequently Asked Questions

What is the difference between black and white POM?

Mechanically, very little — both are the same base polymer. The black color comes from carbon black pigment, which adds slight UV resistance (useful if the part will see sunlight). White POM shows contamination and wear more easily, which can be an advantage in food or medical applications where visual inspection matters. Choose white for visibility, black for UV exposure or cosmetic preference.

Can I glue POM to itself or to metal?

POM has notoriously poor adhesion — it is one of the most difficult plastics to bond. Standard cyanoacrylate (super glue), epoxy, and polyurethane adhesives will peel right off. To bond POM, you need to flame-treat or plasma-treat the surface to activate it, then use a specialized primer (like Loctite 770) followed by a cyanoacrylate adhesive. For most applications, mechanical fastening (threads, press-fit, snap rings) is more reliable than adhesive bonding.

Does POM off-gas or smell when machined?

When machined at correct speeds, POM produces a faint formaldehyde-like odor — this is normal and is the result of trace depolymerization at the cutting edge. At excessive cutting speeds that overheat the material, the odor becomes strong and irritating. Use sharp tools, moderate speeds, and good ventilation. If you are machining large quantities, consider a fume extractor. The finished part does not off-gas.

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