FEP Release Film for Composite Molding: Autoclave, RTM & VARTM Guide

FEP Film as a Release Agent Alternative

FEP (fluorinated ethylene propylene) release film eliminates liquid release agents in composite manufacturing. The non-stick FEP surface prevents resin adhesion up to 200°C without any mold contamination, transfer to parts, or post-mold cleaning.

Process Compatibility

Molding Process	FEP Film Thickness	Temperature	Reuse Cycles	Notes
Autoclave (prepreg)	25 µm	180°C	5–10	Standard aerospace
RTM (liquid resin)	50 µm	120–180°C	10–20	Thicker for pressure
VARTM (vacuum infusion)	25 µm	RT–120°C	3–5	Perforated option available
Compression molding	50 µm	150–200°C	10–15	SMC/BMC
Filament winding	25 µm	120–180°C	Single use	Mandrel wrap

FEP vs Other Release Methods

Method	Release Quality	Part Surface	Contamination	Reuse	Cost/Cycle
FEP film	★★★★★	Mirror (film side)	Zero	5–20×	Medium
PVA solution	★★★	Good	Residue	Single use	Low
Wax paste	★★★	Fair	Some transfer	Single use	Low
Semi-permanent	★★★★	Good	Minimal	5–30 releases	Medium
Chrome plating	★★★★	Excellent	Zero	Permanent	High (initial)

Key Advantage: No Contamination

Unlike liquid release agents, FEP film leaves absolutely no contamination on the composite part surface. This is critical for:

• Bonded assemblies — secondary bonding requires pristine surfaces
• Painted composites — no release agent interfering with paint adhesion
• Medical devices — biocompatibility requires contamination-free surfaces

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