POM Baotailin Nantong M90‑04
POM Baotailin Nantong M90‑04
POM Baotailin Nantong M90‑04 is an injection‑molding copolymer polyoxymethylene grade with balanced comprehensive properties. It is widely applied in multiple fields for favorable mechanical strength, excellent wear resistance, good heat resistance and dimensional stability.
Main Applications
Automotive industry: fuel‑system components (pumps, valves), universal‑joint bearings, motor gears, crankshafts, handles, instrument panels, automotive window‑lift assemblies, electrical switches, seat‑belt buckles 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. Home appliances: household‑appliance components including washing‑machine gears and coffee‑machine parts. Others: precision mechanical parts, zippers, water‑faucet valve cores.
Physical‑Mechanical‑Thermal‑Electrical‑Tribological Properties
| Property Category | Item | Test Standard | Test Data | Unit |
|---|---|---|---|---|
| Physical Properties | Density | ASTM D792 | 1.41 | g/cm³ |
| Water absorption (24 h, 23 °C) | ASTM D570 | 0.22 | % | |
| MFR (190 °C / 2.16 kg) (similar grades for reference) | — | ~9.0 | g/10min | |
| Dynamic friction coefficient (against steel) | ASTM D1894 | 0.15 | — | |
| Dynamic friction coefficient (against POM) | ASTM D1894 | 0.35 | — | |
| Mechanical Properties | Tensile strength (yield) | ASTM D638 | 60 | MPa |
| Elongation at break | ASTM D638 | 60 | % | |
| Flexural strength | ASTM D790 | 96 | MPa | |
| Flexural modulus | ASTM D790 | 2580 | MPa | |
| Notched Izod impact strength (23 °C) | ASTM D256 | 63 | J/m | |
| Unnotched Izod impact strength (23 °C) | ASTM D256 | 760 | J/m | |
| Rockwell hardness (M Scale) | ASTM D785 | 80 | — | |
| Thermal Properties | HDT @1.8 MPa (unannealed) | ASTM D648 | 95.3 (reference value) | °C |
| HDT @1.32 MPa | ASTM D648 | 110 | °C | |
| Coefficient of linear thermal expansion | ASTM D696 | 10 | ×10⁻⁵/℃ | |
| Electrical Properties | Volume resistivity | ASTM D257 | 1×10¹⁴ | Ω·cm |
| Surface resistivity | ASTM D257 | 1×10¹⁶ | Ω | |
| Dielectric breakdown strength | ASTM D149 | 24 | MV/m | |
| Flammability | UL94 rating (1.5 mm) | UL 94 | HB | — |
Injection‑Molding Parameters
| Parameter | Typical Value / Range | Remarks & Instructions |
|---|---|---|
| Drying Treatment | Although POM features low moisture absorption (0.22 %), drying is recommended. Moisture at high temperature triggers degradation, causing bubbles and silver streaks; drying also improves dimensional stability. | |
| Drying temperature | 80‑100 °C | Dehumidifying dryer is recommended. Material bed thickness ≤30 mm for uniform drying. |
| Drying time | 2‑4 h | Ensure sufficiently low moisture content (normally ＜0.2 %). |
| Barrel Temperature | POM has a narrow processing temperature 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) | 150‑170 °C | Near feed throat; avoid over‑temperature to prevent bridging. |
| Middle zone (compression zone) | 170‑190 °C | Main plasticizing zone; keep uniform temperature. |
| Front zone (metering zone) | 180‑200 °C | Close to nozzle; excessive temperature causes POM degradation. |
| Nozzle temperature | 170‑190 °C | Normally slightly lower than front‑zone temperature to prevent drooling; raise moderately in case of blockage. |
| Melt temperature | ~180‑205 °C | Must not exceed 220 °C. Avoid high temperature and long residence time to prevent POM degradation (decomposition temperature approx. 220‑240 °C). |
| Mold temperature | 40‑80 °C (or 60‑80 °C) | High mold temperature (80‑100 °C): uniform crystallization and good toughness, yet longer cooling cycle. Low mold temperature (40‑60 °C): poor surface gloss and high residual stress. Take anti‑burn precautions for hot ejected parts. |
| Injection pressure | 80‑150 MPa | Adjust according to wall thickness and fluidity; 120‑150 MPa for thin‑wall parts, 80‑120 MPa for thick‑wall parts. Relatively high hold‑up pressure (comparable to injection pressure) is required to reduce pressure drop. |
| Injection speed | Medium‑to‑high (30‑80 mm/s) | Too‑fast speed causes turbulence and burning; too‑slow speed leads to short shots and prominent weld lines. Multi‑stage speed control is suggested: low speed for runner filling, medium‑high speed for cavity filling. |
| 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 | 30‑80 rpm | Avoid excessive rotational speed to prevent shear‑heat‑induced degradation. Keep cushion volume low. |
| 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.
