Sheet in POM C 1000x1000 mm black

A sheet in POM C is copolymer acetal in flat stock, meant for milling, sawing or cutting individual parts. The material combines dimensional stability, wear resistance and low friction in a way that has made acetal one of the most used engineering plastics in the workshop industry.

POM C has a density of 1.41 g/cm³, which is heavy for a plastic and gives a compact impression. The long term temperature is 105 degrees and the material takes down to minus 40 without turning brittle. The flammability rating is HB according to UL 94. Water absorption is low, around 0.8 percent at saturation, which makes a difference against polyamide when the dimensions have to hold in a damp or varying environment. Parts turned or milled in POM C keep their tolerances even where PA would draw in moisture and grow.

Mechanically POM C is stiff, tough and has low creep under constant load. Wear resistance is good against steel, brass and other plastics, and the coefficient of friction is low in the dry state. The material has good spring properties, which makes it useful for snap fit constructions and spring clips. Impact strength is higher than in homopolymer acetal (POM H), which is the reason the copolymer version is often chosen for large machined parts where the risk of cracking during machining or under impact load is a problem.

The sheet format is used where the part is flat or is to be cut out of a surface: slide rails in conveyor systems, wear strips in packaging machines, handling fixtures on assembly lines, gears with a wider tooth face milled out of sheet, cam plates, slide blocks in presses and cores in smaller vacuum forming tools. In the food industry POM C turns up in handling components since the material does not absorb moisture and can be cleaned with water without swelling.

Machining is forgiving. Milling gives clean chip formation with sharp tools and enough rake angle. Standard drills in HSS or carbide work. Turning gives a shiny surface straight away and thread cutting is clean both internally and externally. Sawing with a fine toothed band saw blade or circular saw gives straight, clean cuts. The chip is dry and runs off easily, which makes the material friendly in automatic production.

POM C cannot be bonded the way ABS or acrylic can. Mechanical fastening, snap fitting, threaded inserts or ultrasonic welding are the more common methods. If needed, the surface can be activated with flame or plasma treatment before bonding with a special primer, but that is rarely the first choice.

The sheet is usually supplied in natural color, from beige to light yellow-white depending on batch and thickness. The color difference between batches is normal and does not affect the material properties. POM C is also available in black, where a carbon black pigmentation gives a slight improvement in UV resistance outdoors. For longer outdoor exposure, black POM or PE is a better choice than natural colored acetal.

Choosing between POM C and POM H, the rule of thumb is this: POM C is tougher and takes the machining of large parts better, POM H is harder and stiffer but more prone to cracking in thick, milled sections. For flat parts milled out of stock, POM C is almost always the safer choice.

The sheet is handled dry during transport and storage. Direct UV exposure in storage does not affect the material noticeably over reasonable storage times. Do you need help choosing the right thickness or comparing against the homopolymer grades? Get in touch.

The same 1000x1000 mm in black, where the surface hides grease marks on bearings and sliding parts.