Composites Manufacturing

Composites manufacturing builds high strength-to-weight parts by combining fibers and resin in molds, with properties driven by fiber type, orientation, and cure method.

Overview

Composites manufacturing forms parts from fiber reinforcement (carbon fiber, fiberglass) bonded with a resin matrix (typically epoxy, vinyl ester, or polyester). The key value is tailored performance: you place fibers where loads are, tune stiffness with ply orientation, and achieve high strength-to-weight with corrosion resistance.

Choose composites when mass reduction, stiffness, fatigue performance, or non-metallic behavior matters more than tight machining-like tolerances. Tradeoffs include higher process complexity, longer cure cycles, more variability than metals, and the need to design for laminate behavior (anisotropy, interlaminar strength, and bearing/fastener loads).

Common sub-processes include RTM and VARTM for closed-mold infusion parts, prepreg layup with autoclave for highest performance, OOA prepreg for lower capital equipment, filament winding for axisymmetric pressure parts, pultrusion for constant profiles, compression molding for higher-volume shapes, and hand/spray lay-up or chopped fiber for low-cost, lower-structural parts.

Common Materials

  • Carbon fiber/epoxy
  • Fiberglass/vinyl ester
  • Fiberglass/polyester
  • Aramid/epoxy
  • SMC (glass/polyester)
  • Carbon fiber/PEEK

Tolerances

±0.010" to ±0.030" (as-molded); critical interfaces often finish-machined to ±0.003" to ±0.010"

Applications

  • UAV fuselage and wing skins
  • Motorsport monocoque panels
  • Composite pressure vessels (COPV)
  • Wind turbine blade shells
  • Marine hull panels
  • Robotic arm links and covers

When to Choose Composites Manufacturing

Choose composites for parts where weight reduction and directional stiffness/strength are primary requirements and moderate-to-high tooling effort is acceptable. They fit well for low-to-medium volumes, large parts, and structures where a molded surface and integrated features can reduce assembly. Plan for bonded joints and post-machined interfaces where tolerance and sealing are critical.

vs CNC machining

Choose composites when stiffness-to-weight, corrosion resistance, or tailored anisotropic properties matter more than tight, uniform tolerances. Composites also make sense when a molded skin can replace multiple machined parts and fasteners, reducing assembly count. Expect to machine only datums, holes, and sealing surfaces.

vs Injection molding (thermoplastics)

Choose composites when you need structural stiffness and strength beyond typical unfilled or short-fiber injection-molded plastics, especially in larger parts. Composites tolerate lower volumes and larger footprints without the same tooling and press requirements. Injection molding wins when you need very high volume, tight cosmetic repeatability, and integrated small features.

vs Metal fabrication (sheet metal/weldments)

Choose composites when weight and corrosion drive the design and you can benefit from smooth aerodynamic/contoured surfaces without many formed-and-welded pieces. Composites can integrate ribs, skins, and stiffeners in one mold cycle and avoid weld distortion. Metal fabrication is generally faster to iterate when geometry changes frequently and you need tight threaded/bolted features everywhere.

vs Metal casting

Choose composites when you need high specific stiffness, fatigue performance, and non-metallic behavior (EM transparency, corrosion resistance) in medium-to-large parts. Composite tooling and curing can be more manageable than casting for very large shells and panels. Casting is typically better for isotropic strength, high-temperature service, and thin intricate metal features.

vs 3D printing (polymer or metal)

Choose composites when you need repeatable structural properties over large areas and a lower part cost at production volumes after tooling. Composites are well-suited to skins, shells, and tubular structures where fiber direction can be engineered. 3D printing is better for rapid iteration, highly complex internal channels, and very low quantities without tooling.

Design Considerations

  • Define primary load paths early and specify fiber orientation/ply schedule expectations (or performance targets) so suppliers can quote accurately
  • Avoid sharp corners; use generous radii and continuous curvature to improve drape, reduce bridging, and lower scrap
  • Plan hardpoints/inserts for fasteners and bearing loads; don’t rely on thin laminate alone for clamp-up or thread engagement
  • Keep uniform laminate transitions and use tapered ply drop-offs to reduce delamination risk and print-through
  • Call out which surfaces are cosmetic vs. functional, and identify datums that will be post-machined to control tolerance stack-up
  • Specify environment and service temperature (moisture, UV, chemicals, max temp) to drive resin system and cure method selection