High-temperature resistant plastics are widely used in automotive, electronic, and electrical applications due to their excellent thermal stability, mechanical strength, and chemical resistance. These materials typically have high melting points, high processing temperatures, and high sensitivity to molding conditions. Improper temperature settings will result in degradation, silver streaks, burns, insufficient filling, and dimensional instability. This article systematically analyzes the injection molding temperature parameters of common high-temperature resistant plastics and provides practical processing guidelines for on-site production.
I. Temperature Control Requirements for High-Temperature Resistant PlasticsCompared with general plastics, high-temperature resistant plastics require higher barrel and mold temperatures. Most of them are crystalline or high-performance engineering materials with high melt viscosity and poor fluidity. Their processing temperature windows are relatively narrow, and slight overheating may cause thermal decomposition, while low temperature will lead to poor melting and insufficient filling. Therefore, precise temperature control is the key to stable molding. In addition, mold temperature significantly affects crystallinity, shrinkage, and mechanical properties. Most high-temperature materials require higher mold temperatures to ensure complete crystallization and stable dimensions.
II. Injection Molding Temperature Parameters of Common High-Temperature Resistant PlasticsPA66 is the most commonly used high-temperature engineering plastic with a continuous service temperature of about 120°C. The barrel temperature is 260–290°C, nozzle temperature 270–285°C, and mold temperature 60–100°C. Glass fiber reinforced PA66 can increase the temperature by 10–20°C to improve fluidity. It must be fully dried before processing to avoid silver streaks.
PBT is a crystalline polyester with good heat resistance and electrical performance. The barrel temperature is 230–270°C, reinforced grade 240–270°C, nozzle temperature 240–260°C, and mold temperature 80–120°C. High mold temperature helps improve crystallinity and dimensional stability.
PC has high impact resistance and heat resistance with a service temperature of about 120°C. The barrel temperature is 260–300°C, nozzle temperature 270–290°C, and mold temperature 80–110°C. PC is highly hygroscopic and must be dried to avoid bubbles and silver streaks.
POM has excellent wear resistance and fatigue resistance with a service temperature of 100–110°C. The barrel temperature is 180–210°C, nozzle temperature 190–205°C, and mold temperature 60–90°C. POM is prone to thermal decomposition and emits irritating gas, so over-temperature must be strictly prohibited.
PPA is a high-temperature nylon with a service temperature above 150°C. The barrel temperature is 290–330°C, reinforced grade 300–340°C, nozzle temperature 300–330°C, and mold temperature 120–150°C. It requires high mold temperature and sufficient drying.
LCP features low warpage, high fluidity, and high heat resistance. The barrel temperature is 290–350°C, nozzle temperature 300–350°C, and mold temperature 100–150°C. Its processing window is narrow and requires precise parameter control.
PEEK is a super high-performance material with a service temperature up to 250°C. The barrel temperature is 340–390°C, nozzle temperature 350–400°C, and mold temperature 160–200°C. It can only be processed on special high-temperature injection molding machines.
III. General Processing GuidelinesHygroscopic high-temperature materials must be dehumidified and dried to ensure moisture content below 0.01%. Barrel temperature should be set in a gradient: lower in the rear zone and higher in the front zone to prevent premature melting. Nozzle temperature should be slightly higher to avoid cold slugs. For glass fiber reinforced materials, appropriate temperature increase can improve dispersion and fluidity. Mold temperature control is critical for crystalline plastics; insufficient mold temperature leads to low crystallinity, unstable dimensions, and poor mechanical properties.
IV. Common Defects and Temperature Adjustment MethodsSilver streaks and bubbles are usually caused by moisture or overheating. The solution is to strengthen drying and lower barrel temperature. Burns and yellowing indicate severe degradation, requiring temperature reduction and shortened residence time. Short shots and poor flow are caused by low temperature, requiring appropriate temperature increase. Weld lines and poor appearance can be improved by increasing mold temperature.
| Material | Barrel Temp (℃) | Nozzle Temp (℃) | Mold Temp (℃) | Notes |
|---|
| PA66 | 260–290 | 270–285 | 60–100 | Must dry fully |
| PBT | 230–270 | 240–260 | 80–120 | High crystallinity |
| PC | 260–300 | 270–290 | 80–110 | Sensitive to moisture |
| POM | 180–210 | 190–205 | 60–90 | No overheating |
| PPA | 290–330 | 300–330 | 120–150 | High temp & mold temp |
| LCP | 290–350 | 300–350 | 100–150 | Narrow process window |
| PEEK | 340–390 | 350–400 | 160–200 | Special high temp machine |
V. SummaryThe processing of high-temperature resistant plastics depends on precise temperature control. Different materials have specific temperature ranges and requirements. Stable drying, reasonable barrel temperature, and controlled mold temperature are the three core elements. Standardized temperature setting can effectively reduce defects, improve product consistency, and ensure the performance of high-temperature components. Understanding the temperature characteristics of each material helps engineers quickly debug and achieve stable mass production.
