POM machining part

General performance

Polyoxymethylene is a hard and dense material with a smooth, shiny surface, light yellow or white, and the thin wall part is translucent. The burning characteristics are easy to burn, and continue to burn after leaving the fire. The upper end of the flame is yellow, and the lower end is blue. Melting and dripping occur, and there is a strong pungent formaldehyde smell and fishy smell. Polyoxymethylene is a white powder, generally opaque, good colorability, specific gravity 1.41-1.43 g/cm3, 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 it can reach 160°C in the short term. The short-term heat resistance of homopolymerized POM is more than 10°C higher than that of copolymerized POM, but the long-term heat-resistant copolymerized POM is about 10°C higher than that of homopolymerized POM. It can be used for a long time in the temperature range of -40℃～100℃. POM is easily decomposed, and the decomposition temperature is 240 degrees. Irritating and corrosive gases will occur during 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. Its rigidity is very good, commonly known as "Saigang".

(2) It has excellent properties such as fatigue resistance, creep resistance, wear resistance, heat resistance, impact resistance, etc., and has a small friction coefficient and good self-lubrication.

(3) POM is not easy to absorb moisture, the water absorption rate is 0.22～0.25%, the dimensional stability is good in a humid environment, and its shrinkage rate is 2.1% (larger), the size is difficult to control during injection molding, and the heat distortion temperature is 172°C. There are two types of polyoxymethylene, homopolyoxymethylene, with different performance (homopolyoxymethylene has better temperature resistance).

Processing technology

1. POM does not need to be dried before processing, and it is preheated (about 80°C) during processing, which is good for the stability of the product size.

2. The processing temperature of POM is very narrow (0～215℃), and it will decompose when it stays in the barrel for a little longer or the temperature exceeds 220℃, producing strong irritating formaldehyde gas.

3. The holding pressure of the POM material should be relatively large (similar to the injection pressure) to reduce the pressure drop. The screw speed should not be too high and the residual volume should be small;

4. POM products have a large shrinkage rate, which is easy to shrink or deform. POM has a large specific heat and a high mold temperature (80-100°C). The product is very hot when it is demolded, so it is necessary to prevent burning fingers.

5. POM should be molded and processed under the conditions of "medium pressure, medium speed, low material temperature, higher mold temperature", and mold temperature control is required when precision products are molded.

6. POM has high mechanical strength and rigidity

7. Higher POM fatigue strength

8. POM environmental resistance, good resistance to organic solvents

9.POM has strong resistance to repeated impacts, good electrical properties, good recovery, self-lubricity, good wear resistance, and excellent dimensional stability.

Acting as an agent of POM American DuPont 100P: Basic introduction and processing technology of POM

Polyacetal resin (POM) is DuPont's high-performance polymer business unit's first impact-resistant modified POM, which can meet the stringent requirements of the automotive industry for interior plastics. This extends the application of Delrin? POM resin in automobiles to interior plastic parts to cope with the requirements of high impact loads.

Auto industry

Polyoxymethylene is widely used in the automotive industry. The parts made of polyoxymethylene have good effects such as reducing lubrication points, wear resistance, easy maintenance, simplifying the structure, improving efficiency, reducing costs, and saving copper materials. Substituting copper for the production of half-shafts and planetary gears on automobiles not only saves copper, but also increases the service life. In the engine fuel system, POM can manufacture parts such as radiator water pipe valves, radiator tank caps, coolant spare tanks, water valve bodies, fuel tank caps, water impellers, vaporizer housings, accelerator pedals and other parts.

Electronic appliances

Due to its low power consumption, high dielectric strength and insulation resistance, and arc resistance, polyoxymethylene has been widely used in the field of electronics and electrical appliances. For example, polyoxymethylene can be used to manufacture electric wrench shells, electric wool shears shells, coal drill shells and switch handles, etc., as well as telephones, radios, tape recorders, video recorders, televisions, computer and fax machine parts, timer parts, tape recorders, etc. seat.

Construction: It can be used as taps, window frames, wash basins, water tanks, curtain pulleys, water meter shells and water pipe joints, etc.

Agricultural machinery: parts of manual sprayer, connection and intermodal parts of planter, movable parts of milking machine, housing of drainage and irrigation water pump, inlet and outlet valve seats, joints and sleeves, etc. It can also be used for aerosol packaging, conveying pipes, parts immersed in oil, and standard resistance panels, etc.Can overcome the easiness of pure PTFE

POM has a very low coefficient of friction and good geometric stability, especially suitable for making gears and bearings. Because it also has high temperature resistance, it is also used in pipeline devices (pipe valves, pump housings)

Main product