(1)POM can not be dried before processing, it is best to preheat in the process of processing (about 80ºC), which is good for the stability of product size.
(2) THE processing temperature of POM is very narrow (0~215ºC), and it will decompose when the residence time in the barrel is slightly longer or the temperature exceeds 220ºC, producing strong irritant formaldehyde gas.
(3) When POM material is injected, the holding pressure should be larger (similar to the injection pressure) to reduce the pressure drop. Screw speed can not be too high, the residual amount should be less;
(4) POM products have a large shrinkage rate and are prone to shrinkage or deformation. POM specific heat, high mold temperature (80~100ºC), the product is very hot when demoulding, need to prevent burns fingers.
(5) POM should be formed under the conditions of "medium pressure, medium speed, low material temperature and high mold temperature", and the mold temperature should be controlled when precision products are formed
(6) With high mechanical strength and rigidity
(7) The highest fatigue strength
(8) Environmental resistance, good resistance to organic solvents
(9) Strong resistance to repeated impact, good electrical properties, good recovery, with their own lubrication, good wear resistance, good dimensional stability.
Paraformaldehyde is a smooth, shiny hard and dense material, light yellow or white, thin wall part is translucent. Combustion characteristics are easy to burn, from the fire to continue to burn, the upper end of the flame is yellow, the lower end is blue, melting dripping, there is a strong irritant formaldehyde taste, fishy smell. Polyformaldehyde is white powder, generally opaque, good coloring, specific gravity 1.41-1.43 grams/cubic centimeter, molding shrinkage rate 1.2-3.0%, molding temperature 170-200ºC, drying conditions 80-90ºC 2 hours. The long-term heat resistance of POM is not high, but it can reach 160ºC in the short term. The short-term heat resistance of homopolymer POM is more than 10ºC higher than that of copolymer POM, but the long-term heat resistance of copolymer POM is about 10ºC higher than that of homopolymer POM. It can be used in the temperature range of -40ºC~100ºC for a long time. POM is easily decomposed at 240 ° C. Irritant and corrosive gases occur when decomposition, so the mold steel should be made of corrosion-resistant materials.
(1)POM is a crystalline plastic with a density of 1.42g/cm3. It has good rigidity and is commonly known as "Match steel ".
(2) It has excellent performance of fatigue resistance, creep resistance, wear resistance, heat resistance, impact resistance, and small friction coefficient, good self-lubrication.
(3)POM is not easy to hygroscopic, water absorption rate is 0.22~0.25%, in the humid environment, good dimensional stability, its shrinkage rate is 2.1%(larger), injection size is difficult to control, hot deformation temperature is 172ºC, POM has two kinds of paraformaldehyde, different performance (paraformaldehyde temperature resistance is better).
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