Make · process

Resin infusion (RTM / VARTM)

Dry fibre laid in a mould, then resin drawn through it

Dry fibre is laid up — no messy prepreg — sealed under a bag or in a closed mould, and liquid resin is drawn through it by vacuum or pressure. It is how the biggest composite parts on earth, wind-turbine blades and boat hulls, are made.

Low–moderate
Volume
Moderate
Tooling
Hours
Cycle
Moderate
Tolerance
How it works
  1. 1
    Lay a dry fibre preform in or on the mould.
  2. 2
    Seal it under a vacuum bag (VARTM) or close the mould (RTM).
  3. 3
    Draw liquid resin through the fibre by vacuum or pressure.
  4. 4
    Cure, demould and finish.
Strengths & limits
Strengths
  • Very large parts in one shot
  • Cheaper than prepreg — no frozen storage
  • Good fibre content, low voids
  • Cleaner, low-emission (closed mould)
Limits
  • Resin flow must reach everywhere — dry spots ruin the part
  • Slower than the injection processes
  • Preform and flow design are exacting
Typical parts & materials

Typical parts: Wind-turbine blades, boat hulls, large panels, automotive body parts

Commonly run in — open one for its cited properties:

E-glass/epoxyVinyl esterPolyesterEpoxy

Part of the Make map of manufacturing processes. Browse the cited database, or see where these parts end up in the application domains.