POM Baotailin Nantong M90‑44
POM Baotailin Nantong M90‑44
POM Baotailin Nantong M90‑44 is a medium‑viscosity injection‑molding copolymer polyoxymethylene with balanced comprehensive properties. It is widely used in multiple fields for good mechanical strength, excellent wear resistance and dimensional stability.
Main Applications
Automotive industry: fuel‑system components (fuel pumps, fuel‑tank caps), seat‑belt parts, universal‑joint bearings, motor gears, crankshafts, handles, instrument panels, automotive window‑lift assemblies, electrical switches and other auto accessories. Industrial components: engineering parts requiring wear resistance and self‑lubrication, such as gears, bearings, cams, sliders, pump housings and valves. Especially suitable for mechanism gears inside printers and copiers. Electrical‑electronic: electrical components, connectors and housings requiring good insulation and mechanical strength; AV devices such as DVD players and Blu‑ray disc players. Home appliances: components for washing‑machines, refrigerators, electric shavers and other household appliances. Others: precision mechanical parts, zippers, window‑frame and shutter components, toys, sports‑equipment parts.
Physical‑Mechanical‑Thermal‑Electrical‑Tribological Properties
| Property Category | Item | Test Standard | Test Data | Unit |
|---|---|---|---|---|
| Physical Properties | Density | ISO 1183 | 1.41 | g/cm³ |
| Water absorption (24 h) | ISO 62 | 0.22‑0.50 | % | |
| MFR (190 °C / 2.16 kg) | ISO 1133 | 8.0‑9.0 | cm³/10min or g/10min | |
| Molding shrinkage (flow direction) | ISO 294‑4 | 2.0‑2.2 | % | |
| Mechanical Properties | Tensile strength (yield) | ISO 527‑2 | 60.0‑62.0 | MPa |
| Elongation at break | ISO 527‑2 | 35‑60 | % | |
| Flexural strength | ISO 178 | 87.0‑96.0 | MPa | |
| Flexural modulus | ISO 178 | 2500‑2700 | MPa | |
| Charpy notched impact strength (23 °C) | ISO 179/1eA | 6.0‑6.5 | kJ/m² | |
| Rockwell hardness (M Scale) | ISO 2039‑2 | 80 | — | |
| Thermal Properties | HDT (1.8 MPa) | ISO 75‑2/A | 95.0‑110 | °C |
| Melting point | DSC | 165‑166 | °C | |
| Coefficient of linear thermal expansion | ISO 11359‑2 | 1.2E‑4 | cm/cm/°C | |
| Electrical Properties | Volume resistivity | IEC 60093 | 1.0E+14 | Ω·cm |
| Surface resistivity | IEC 60093 | 1.0E+16 | Ω | |
| Dielectric strength | IEC 60243‑1 | 19‑24 | kV/mm | |
| Flammability | UL94 rating (1.5 mm) | UL 94 | HB | — |
Injection‑Molding Parameters
| Parameter | Typical Value / Range | Remarks & Instructions |
|---|---|---|
| Drying Treatment | Although POM has low moisture absorption (0.22%‑0.50%), drying is recommended. Moisture at high temperature will cause degradation, bubbles and silver streaks; drying also improves dimensional stability. | |
| Drying temperature | 80‑90 °C | Dehumidifying dryer is recommended. |
| Drying time | 3‑4 h | Ensure sufficiently low moisture content (normally ＜0.2 %). |
| Barrel Temperature | POM has a narrow processing window. Temperature shall never exceed 220 °C; otherwise irritating formaldehyde gas will be generated. Material residence time in barrel shall not exceed 20 minutes. | |
| Rear zone (feed zone) | 170‑180 °C | Near feed throat. Avoid over‑temperature to prevent bridging. |
| Middle zone (compression zone) | 180‑190 °C | Main plasticizing zone; keep uniform temperature. |
| Front zone (metering zone) | 190‑210 °C | Close to nozzle. Excess temperature causes POM degradation. |
| Nozzle temperature | 190‑210 °C | Usually slightly lower than front‑zone temperature to prevent drooling. |
| Melt temperature | 190‑210 °C | Do not exceed 220 °C. Avoid high temperature and long residence time to prevent POM degradation (decomposition temperature approx. 220‑240 °C). |
| Mold temperature | 60‑80 °C (or 80‑105 °C) | Higher mold temperature improves crystallinity, dimensional stability and surface gloss, yet prolongs cooling cycle. |
| Injection pressure | 49.0‑98.0 MPa (or 700‑1200 bar) | Higher injection pressure is required due to high melt viscosity. Hold‑up pressure is generally 50‑70 % of injection pressure. |
| Injection speed | Medium‑to‑high | Too fast causes turbulence and burning; too‑slow leads to short shots and prominent weld lines. |
| Hold‑up pressure | 50‑70 % of injection pressure | Compensates POM shrinkage, reduces sink marks and dimensional deviation. |
| Hold‑up time | 5‑15 s | Adjust according to part wall thickness. |
| Back pressure | 0.5‑2.0 MPa | Low back‑pressure improves melt homogeneity and degassing; excessive back‑pressure causes overheating and degradation. |
| Screw speed | 100‑150 rpm | Avoid excessive rotational speed to prevent shear‑heat‑induced degradation. |
| Cooling time | 10‑30 s | Adjust according to part thickness and mold temperature to ensure full cooling and anti‑deformation upon ejection. |
Note: All data above is for reference only.
