Polypropylene (PP) is one of the most versatile and widely used thermoplastics. To achieve optimal results—whether you're molding consumer products, automotive components, or packaging—it's essential to dial in the right process parameters. Here’s a clear, actionable breakdown of key PP molding settings.
Zone Temperature Range (Typical Setting)
Zone | Temperature Range (Typical Setting) |
Hopper | 30–50°C (50°C) |
Zone 1 | 160–250°C (200°C) |
Zone 2 | 200–300°C (220°C) |
Zone 3 | 220–300°C (240°C) |
Zone 4 | 220–300°C (240°C) |
Zone 5 | 220–300°C (240°C) |
Nozzle | 220–300°C (240°C) |
Melt Temperature: 220–280°C
Barrel Residence Temp: 220°C
Mold Temperature: 20–70°C
Parameter | Recommended Value |
Injection Pressure | 80–100 MPa (800–1000 bar); up to 180 MPa (1800 bar) for thin-wall packaging |
Holding Pressure | 30–60% of injection pressure |
Back Pressure | 5–20 MPa (50–200 bar) |
Injection Speed | High for thin-wall packaging; moderate for general parts |
Parameter | Setting |
Screw Speed | High (peripheral speed ≈ 1.3 m/s) |
Metering Stroke | (0.5–4)D |
Cushion | 2–8 mm |
✅ A 4D screw stroke provides sufficient residence time—key for melt homogeneity.
Pre-Drying: Not required. Only 1h at 80°C if stored in poor conditions.
Regrind Usage: Up to 100% regrind possible.
Shrinkage: 1.2–2.5%. Stabilizes after 24 hours.
Gating: Pin-point or multi-point gates; hot runners; gate at thickest section to minimize sink marks.
Purge: No special purging required. PP withstands temperature variations well.
Screw Design: Standard three-zone screw. Use open nozzle or non-return valve for packaging.
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