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Learn more about "POM" (CNC machining programming)

Aug 13,21

Learn more about "POM" (CNC machining programming)

POM "POM density: 1.42g /mL at 25 °C.(42 g 1. The density of POM was 1.42 g/mL.)

General performance
POM is a hard and dense material with a smooth, shiny surface, yellowish or white, and the thin-walled parts are translucent.
The combustion characteristics are easy to burn, and continue to burn after leaving the fire. The upper end of the flame is yellow, the lower end is blue, and melting drops occur. There is a strong irritant formaldehyde smell and fishy smell.
Poformaldehyde 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 170-200℃, drying conditions 80-90℃ for 2 hours.
The long-term heat resistance of POM is not high, but can reach 160℃ in the short term. The short-term heat resistance of homopolymer POM is more than 10℃ higher than that of copolymer POM, but the long-term heat resistance of copolymer POM is about 10℃ higher than that of homopolymer POM.
It can be used in the temperature range of -40℃ ~ 100℃ for a long time.
POM is easy to decompose at a temperature of 240 degrees.
Irritant and corrosive gases occur when decomposition occurs, so the mould steel should be made of corrosion-resistant materials.
(1) POM is a crystalline plastic with a density of 1.42g/cm3. Its rigidity is very good and it is commonly known as "sai steel".
(2) It has fatigue resistance, creep resistance, wear resistance, heat resistance, impact resistance and other excellent properties, and small friction coefficient, good self-lubrication.
(3) POM is not easy to moisture absorption, water absorption rate of 0.22 ~ 0.25%, good dimensional stability in a humid environment, its shrinkage rate of 2.1%(large), size is difficult to control when injection molding, thermal deformation temperature of 172℃, there are two kinds of POM, different performance (homopolyaldehyde temperature resistance is better).
Mechanical properties of
POM has high strength, stiffness, good elasticity, wear reduction and wear resistance.
Its mechanical properties are excellent, the specific strength can reach 50.5mpa, the specific stiffness can reach 2650MPa, and the metal is very close.
The mechanical properties of POM changed little with temperature, and the change of copolymer POM was slightly larger than that of homopolymer POM.
The impact strength of POM is higher than that of ABS and PC.
POM is sensitive to notch, which can reduce the impact strength by as much as 90%.
The fatigue strength of POM is very outstanding. After 10 alternating loads, the fatigue strength can reach 35MPa, while that of PA and PC is only 28MPa.
The creep of POM is similar to that of PA, which is only 2.3% at 20℃, 21MPa and 3000h, and is very little affected by temperature.
POM has small friction coefficient and good wear resistance (POM>
PC), the limit PV value is large, and the self-lubricating property is good.
POM products on grinding, high load action is easy to produce similar to the scream noise.
Electrical performance
POM electrical insulation is good, almost not affected by temperature and humidity;
The dielectric constant and dielectric loss vary little over a wide range of temperature, humidity and frequency.
Excellent arc resistance and can be maintained at high temperatures.
The dielectric strength of POM is related to the thickness, which is 82.7kV/mm when the thickness is 0.127mm and 23.6kV/mm when the thickness is 1.88mm.
Environmental performance
POM is not resistant to strong alkali and oxidant, and has certain stability to enoic acid and weak acid.
POM has good solvent resistance, hydrocarbon, alcohols, aldehydes, ethers, gasoline, lubricating oil and weak base, and can maintain considerable chemical stability at high temperature.
Small water absorption, good dimensional stability.
The weather resistance of POM is not good. Under the action of ultraviolet radiation for a long time, the mechanical properties of POM will decline, and the surface will be pulverized and cracked.
Crystallizing material, melting range is narrow, melting and solidification is fast, the material temperature is slightly lower than the melting temperature that crystallization occurs.
Medium flow.
Moisture absorption is small, can not be dried