POM - Polyoxymethylene
POM – Polyacetal – Acetalplast – polyformaldehyd – Polyoksymetylen – Polyoxymethylene – polyformaldehyde
POM – Application: Used in almost all industries including mechanical engineering, food industry and the automotive industry. used bla. a. Wheel rolls pulleys knots impeller pump housings water meters hinges fuel caps bearings and plain bearings petrol pumps screws handle gear bushings steering wheels gear bearings gear guide rails screws, snap locks.
Fire :It burns with clear blue flame without visible smoke. Pungent smell like formaldehyde. Because of the oxygen content of the molecules are POM highly flammable and more flammable than PA and PET. Flammable class UL 94 HB. Ignition temperature 375 ° C. POM burns to CO2 and water from incomplete combustion.
Electrical properties : The insulation properties are good, and there are high becom-strength. Dielectric loss levels are low . POM POM-H and C have different properties. The electrical properties are affected by temperature and humidity to a limited extent.
Should not be used with corona plants , resulting in creep voltage , as the surface over time changed.
Colors: POM is white to colorless in an undyed state. Usually in the colors of nature (white) or black. Can be dyed in all colors.
Fugtoptagelse 50%RF: 0,2-0,8 %. Fugtoptagelsen is a maximum of about. 1% and usually does not mean anything for properties.
Physiological properties: The food industry uses POM to a great extent, the material is easy to clean and is not affected by the cleaners, normally used. POM can be approved by US (FDA) and German (BGA) authorities for use in machines for food.
History: Polyacetal has been on the market since 1959. Acetal, was first developed in the late 1950s, som en homopolymer ved DuPont Delrin®, og som copolymer ved Ticona’s Celcon®.
Indifikation brandprøve: It burns with clear blue flame without visible smoke. Pungent smell like formaldehyde.
Category: Delkrystallinsk material.
Chemical resistance: Resistant to most hydrocarbons as essential, petrol, alcohol and other fuels, oil, but not esters. POM-H are generally less resistant than the POM-C. This also applies to hot water (hydrolysis), where POM-H not tolerate Vandals over 65 ° C. POM-C is more than kemirestens POM-H. Resistant to weak acids at pH below 4 and most bases.
Chemical structure: Polyacetal st and delkrystallinsk termoplast. Density 1,41 g/cm³. POM can be found in 2 types of homopolymer and copolymer wherein the copolymerede POM-C is now the standard. Copolymer have better chemical, but poorer mechanical and thermal properties.
Delivery: POM-C comes in rundstænger (Available center less-polished), hollow bars and plates both in variety and nature. As intermediate goods are available POM in two types – POM-H og POM-C. POM-C, is today the most common.
Bonding: Bonding quite difficult, and large forces is not achieved. There can be used on two- component epoxy-based or polyurethane adhesive. Before the bonding surface should be rough, which is best achieved with a chemical etching or mechanical grinding.
Mechanical properties: pen, dimensionsstabilt, hard and resilient plastics , with a high impact strength and poor koldflydningstendens. Has good range of properties such as sliding material, When modglidefladen is smooth. POM-H is tougher, stiffer and more wear-resistant than the POM-C because of the higher crystallinity.
Friction 0,3 m
Tensile Strength 65 Mpa
Kærvsejhed 6,5 KJ/m²
Elasticitetsmodul 2700 MPa
Ball pressure hardness 135 N / mm² .
Environment: Formaldehyde can cause cancer and irritation in the airways.
When heated above 260ºC kan POM dekomponere, wherein formaldehyde is released gases, which implies a danger of explosion.
The processing can be smelt. POM can be recycled.
Optical properties: Delkrystallinsk material, impermeable to visible light.
Surface treatment: Parts can be metallised or colored by printing and varnishing. A chemical or electrical pretreatment is necessary for good adhesion.
Cleaning: Used largely in food industry, the material is easy to clean and is not affected by the cleaning products, normally used.
Assembly (mechanical): Collection of bolts is the most used.
It is perfectly cut a thread in the POM, but an even stronger collection please
using threaded inserts or self-tapping screws for plastics.
Injection molding: Can be processed by injection molding, extrusion, blow molding, rotationsstøbning og termoformning.
The processing temperature of the injection molding and extrusion is approximately. 200ºC.
Can be reinforced with glass and other reinforcement materials.
Cutting: Can easily and quickly processed to common machine tools.
The plastic is kortspånet, and the surface will get a good finish with properly sharpened tool.
Rods are available centerless grinding cut.
Welding: Varmespejl 210-230 ° C strength ca. 90% – hot air welding with nitrogen 240-260 ° C strength ca. 30% – friction welding strength ca. 50-70% – ultralydssvejsning – viberationssvejsning.
Thermal Properties. The impact strength decrease with decreasing temperatures and are not normally used during – 40°C, because less impact resistance is very low. Over 85-100 ° C should not be used POM renewable. Tolerates short term temperatures up to 140 ° C.
When used in hot water above 65 ° C may result in brittleness and cracking (hydrolysis).
Stiffness is temperature dependent and decreases much with rising temperature
near the crystalline melting point at about. 166°C (POM-C) respectively 175 ° C
(POM-H).
UV- Stability: POM is not UV stable, but by black and specially stabilized types can be used outdoors.
Thermoforming (Termoformning): Hot bending as well as a thermoforming is possible, if one controls the temperature accurately. Material temperature should be 160 -170°C, which is close to the melting temperature. At this temperature the plastic transparent.
Density: 1,40 – 1,42
