Minimum 450°C heating is required when processing high-temperature materials like PEEK, which melts between 380–420°C. Barrels must use ceramic or mica band heaters capable of sustaining ≥450°C. Precision temperature control using 5–8 independently PID-controlled zones ensures thermal degradation is minimized, with stability within ±1°C. A heat-up rate of ≥4°C/min helps avoid prolonged material exposure.
Efficient melting without excessive shear heating is achieved through a compression ratio of 2.0–2.5:1 (e.g., 2.2:1 for PEEK) and an L/D ratio of 22:1–24:1 for optimal melt homogenization. Durable materials like dual-hardened steel (DIN 1.2767) or bimetallic barrels, along with tungsten carbide-coated screws, are essential to resist wear from abrasive fillers.
High melt viscosity materials require 20–25% higher clamping tonnage than standard plastics. For example, a part normally requiring 400 tons may need 500 tons when using PEEK to prevent flash and ensure full cavity fill.
Injection systems must deliver ≥2,500 bar pressure to mold thin-walled parts, such as electrical connectors. Servo-electric drives offer acceleration responses under 50 ms for repeatable performance.
High torque (≥25 Nm/cm³) and optimized screw RPM (80–120 rpm) are required to rotate screws against viscous high-temp melts while balancing throughput and shear heating.
For mold thermal control, oil-based TCUs up to 230°C or pressurized water systems (up to 180°C) provide stability within ±0.5°C—essential for minimizing warpage in semi-crystalline polymers.
Materials like PEEK demand strict drying conditions: desiccant dryers with ≤ -40°C dew point and 150–180°C drying capacity for at least 4 hours. Closed conveying systems with nitrogen purging prevent oxidation during transfer.
Insulated barrels help minimize heat loss and energy consumption. Ceramic thermocouples prevent melt stagnation and degradation.
Wear-critical parts like check rings and nozzles must withstand abrasive compounds. Tungsten carbide or PEEK-coated check rings and reverse-taper shut-off nozzles prevent material drool and premature wear.
Safety features include barrel cooling systems (air/water jackets) to prevent overheating during downtime and exhaust systems to safely manage byproducts like H2S from PPS decomposition.
Melt pressure sensors with ≤1 ms response times and in-line viscosity monitoring enable real-time process corrections, reducing defects and enhancing consistency.
Modern machines log thermal profiles, cushion consistency, and screw positions with ±0.01 mm repeatability—critical for ensuring high-yield production in regulated industries.
| Component | Standard Machine | High-Temp Machine |
|---|---|---|
| Barrel Heaters | Mica (max 350°C) | Ceramic (450°C+) |
| Screw Material | 4140 Steel | Nitrided or Bimetallic |
| Clamping | Toggle | Direct Hydraulic (higher tonnage) |
| Drive | Hydraulic | Servo-Electric (precision) |
In one medical device facility, high-temperature injection molding of PEEK spinal implants was successfully implemented using the Engel e-motion 440 servo-electric machine. The machine operated with a 400°C barrel temperature, 180°C mold temperature, and 2,200 bar injection pressure. The outcome included consistent tensile strength (>95 MPa) and compliance with ISO 13485 standards—demonstrating real-world effectiveness and production quality.
Thermal Precision: Accurate and consistent barrel temperatures are foundational to high-temp molding success.
Mechanical Performance: High torque, clamping force, and abrasion resistance are mandatory for handling aggressive polymers.
Integrated Systems: Drying, TCUs, and safe material handling systems must work in tandem with the press.
Using inadequate machinery for high-temperature materials like PEEK, PPS, or PEI can result in material degradation, tool failure, and production waste. Brands like Engel, Arburg, and Sumitomo (SHI) lead the field with injection molding platforms specifically engineered for these polymers.
The margin for error in high-temp molding is measured in degrees and microns—engineer accordingly.
