Automotive Composites & Compression Tooling

Carbon Fiber SMC Compression Molding & Charge Nesting Calculator

Non-isothermal squeeze flow rheology, charge coverage optimization, and automated CNC knife nesting generator for structural carbon fiber SMC.

Process Parameters & Inputs

Finished Part Projected Area ($A_{\text{part}}$ in $\text{cm}^2$):

Total 2D surface area of compression molded automotive panel.

Initial SMC Charge Coverage Target (%):

Percentage of mold cavity covered by pre-cut SMC charge stack (typically 50 - 70%).

Finished Part Thickness ($t_{\text{nom}}$ in mm):

Nominal finished panel wall thickness.

SMC Raw Sheet Areal Weight ($\text{g/m}^2$):

Areal weight of raw uncured carbon fiber vinyl ester SMC sheet.

Hydraulic Press Clamping Force ($F$ in Tonnes):

Hydraulic molding press clamping capacity.

Calculated Engineering Metrics

Charge Nesting Area ($A_{\text{charge}}$)

1820cm²

Required SMC Ply Stack Count

2plies

Cavity Molding Pressure ($P_{\text{cav}}$)

15.7MPa

Shear Edge Parting Clearance

0.075mm

Toolpath & Geometry Simulation

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Engineering Methodology & Technical Notes

Carbon Fiber Sheet Molding Compound (CF-SMC) Rheology: CF-SMC consists of chopped carbon fiber bundles ($25\text{--}50\text{ mm}$ length, $50\% - 60\%$ fiber volume) in a thermoset vinyl ester or epoxy resin matrix. Under high hydraulic press tonnage ($10\text{--}20\text{ MPa}$ cavity pressure at $140\text{--}160^\circ\text{C}$), the charge undergoes non-isothermal squeeze flow to fill complex ribs and bosses. Charge coverage is calibrated to $50\% - 70\%$ to allow sufficient flow for air expulsion without causing severe fiber-matrix separation or knit line weakness.

2D Charge Nesting DXF Prepress & Automated CNC Cutting: Raw SMC rolls must be automated-cut on CNC oscillating knife tables (Zünd, Eastman) using nested 2D DXF charge blanks. SpotItLive optimizes charge geometry and perimeter offset curves to eliminate air entrapment and minimize scrap trim.