EXTRUSION BLOW MOLDING & PLASTIC CONTAINER TOOLING

Blow Molding Pinch-Off Land & Parison Tooling Calculator

Calculate blow molding bottom pinch-off cutting land width (W_p), blow-up ratio (BUR), flash relief pocket angles, and parison extrusion swell for HDPE, PP, and PET bottles.

1. Input Parameters

Container Nominal Volume [mL]

Max Mold Cavity Width / Diameter [mm]

Finished Container Nominal Wall Thickness [mm]

Resin Polymer & Extrusion Swell

2. Calculation Results

Pinch-Off Land Width (W_p)

0.0 mm

Blow-Up Ratio (BUR)

0.00:1

Flash Relief Angle (θ)

30.0°

Est. Parison Wall Extruded

0.0 mm

3. Geometric Visualizer

Tooling & Vector Prepress Engineering Notes

1. Pinch-Off Land Width Rule: For HDPE containers, pinch-off cutting land width is $W_p = 0.8 imes t_{\text{wall}}$ (typically $0.6 - 1.0\text{ mm}$). Excessively wide lands create thick, rigid weld seams prone to drop-impact splitting.

2. Flash Pocket Depth: The flash relief cavity must provide depth $D_{\text{flash}} \ge 1.5 \times t_{\text{flash}}$ to prevent mold clamp tonnage dissipation across flash rather than the parting line.

3. CNC Mold Split Parting Line DXF: Blow mold parting lines require vacuum venting micro-slits ($0.03\text{ mm} \times 6.0\text{ mm}$) at container corners to eliminate trapped air entrapment.