Thermoregulators in Plastic Industry: Application Guide for HVAC
Precise temperature control is fundamental in plastic processing. Thermoregulators ensure dimensional quality, surface finish, and productivity in injection, extrusion, and blow molding operations.
Why Use Thermoregulators?
Proven Benefits
- Quality: Parts with precise dimensions and uniform finish
- Productivity: Faster and more consistent cycles
- Economy: Less scrap and rework
- Repeatability: Stable process batch by batch
Problems Without Temperature Control
- Sink marks and voids
- Warping and distortion
- Visible weld lines
- Irregular gloss
- Long and variable cycles
Temperatures by Polymer Type
Amorphous Polymers
| Material | Mold Temp. | Melt Temp. |
|---|---|---|
| PS (Polystyrene) | 68-140°F (20-60°C) | 356-500°F (180-260°C) |
| ABS | 104-176°F (40-80°C) | 392-500°F (200-260°C) |
| PC (Polycarbonate) | 176-248°F (80-120°C) | 536-608°F (280-320°C) |
| PMMA (Acrylic) | 104-194°F (40-90°C) | 392-482°F (200-250°C) |
| Rigid PVC | 68-140°F (20-60°C) | 320-392°F (160-200°C) |
Semi-Crystalline Polymers
| Material | Mold Temp. | Melt Temp. |
|---|---|---|
| PP (Polypropylene) | 68-176°F (20-80°C) | 392-536°F (200-280°C) |
| PE (Polyethylene) | 68-140°F (20-60°C) | 356-536°F (180-280°C) |
| PA (Nylon) | 140-212°F (60-100°C) | 464-572°F (240-300°C) |
| POM (Acetal) | 140-248°F (60-120°C) | 356-428°F (180-220°C) |
| PET | 248-284°F (120-140°C) | 500-554°F (260-290°C) |
Engineering Polymers
| Material | Mold Temp. | Melt Temp. |
|---|---|---|
| PBT | 140-212°F (60-100°C) | 446-518°F (230-270°C) |
| PPO/PPE | 176-248°F (80-120°C) | 500-572°F (260-300°C) |
| PPS | 248-302°F (120-150°C) | 572-644°F (300-340°C) |
| PEEK | 302-392°F (150-200°C) | 662-752°F (350-400°C) |
| LCP | 176-302°F (80-150°C) | 536-662°F (280-350°C) |
Thermoregulator Sizing
Basic Formula
P = (m × Cp × ΔT) / t
Where:
- P = Required power (kW)
- m = Mold mass (kg)
- Cp = Specific heat of steel (0.12 kcal/kg.°C)
- ΔT = Temperature difference (°C)
- t = Desired heating time (h)
Practical Example
Mold of 500 kg, heating from 77°F (25°C) to 176°F (80°C) in 30 minutes:
P = (500 × 0.12 × 55) / 0.5 = 6,600 kcal/h ≈ 7.7 kW
Recommendation: Thermoregulator of 9-12 kW (with safety margin)
Water or Thermal Oil?
Water Thermoregulator
- Maximum temperature: ~302°F (150°C) (pressurized up to 356°F (180°C))
- Advantages: Lower cost, safer, better heat transfer
- Ideal for: PP, PE, PS, ABS, PVC
Thermal Oil Thermoregulator
- Maximum temperature: up to 662°F (350°C)
- Advantages: High temperatures, no pressurization
- Ideal for: PC, PA, POM, PET, engineering polymers
Best Application Practices
- Independent circuits: Each mold zone with its own control
- Adequate flow rate: Minimum 5.3 GPM (20 L/min) per circuit
- Insulated hoses: Avoid heat loss
- Preventive maintenance: Periodic cleaning of channels
- Monitoring: Record temperatures for process control
Conclusion
The correct thermoregulator makes a difference in quality and productivity. Helioterm offers thermoregulators from 6 to 150 kW for all plastic applications. Consult our technical team!