When to 3D Print Fiber Layup Molds

Fiber-reinforced plastics are a unique solution for engineers in aerospace, automotive and sporting goods because of their incredible strength-to-weight ratio. The combination of fibers and polymer form a new material with improved physical properties. There are two main categories of molding processes to produce fiber layups: wet layup, in which fibers are applied to a mold and resin is brushed onto the cloth by hand, pressure is applied to eliminate air bubbles and cured, or prepreg (pre-impregnated), in which fibers have resins already absorbed and just need to be applied to the mold before pressure application and curing begins.
fiber layup

So what do fiber layups have to do with additive manufacturing?

Although fiber layups have many applications, it can be an expensive process to automate, especially when you’re producing customized parts. Manufacturers have started using 3D printing technologies to create the molds and masters for wet and prepreg fiber layups to reduce costs, shorten lead times and improve accuracy.

Traditionally molds and masters are made with CNC machining or by hand. Handcrafting the molds is obviously time-consuming and labor intensive, but even CNC machining can be challenging when you have parts with complex geometries and tight deadlines with no room to wait on machine shops.

Producing molds and masters with Fused Deposition Modeling (FDM) or PolyJet technology addresses the challenges of traditional manufacturing methods, offering the following benefits:

  • Reduced lead time – No need to wait on the machine shop. Upload your 3D CAD file and print out the mold at a service bureau or on an in-house printer.
  • Reduced cost – Less labor intensive, generally less expensive than machining and no cost penalties for design updates.
  • Inert mold material that doesn’t inhibit curing – Materials can withstand high pressure vacuum processes.
  • Stability, eliminating distortion from heat – There are many high-temperature engineering thermoplastics and photopolymers compatible with fiber layup resin and epoxy.
  • Decreased core weight – FDM offers the ability to print lattice structures within parts instead of solid to reduce weight.
Producing molds with FDM or PolyJet is a viable option when:
  • Tool geometries are difficult to machine
  • Low production volumes – When handcrafting and CNC are not cost effective or as a bridge to tooling.
  • Parts are customized or constantly changing – Making design adjustments is as simple as updating the CAD file and printing out a new mold.
Large and intricate detail – 3D printing can produce complex geometries that traditional methods can’t, giving you complete design freedom.

More specifically, PolyJet is perfect for fiber layup parts that require a very smooth surface finish. The fine resolution reduces surface preparation needed to create a smooth part. FDM is a better fit for molds that need to withstand high temperature resins and epoxies or high pressure vacuuming because of its durable, engineering thermoplastics. FDM is also a good fit for large parts. Because of the ability to build and bond multiple sections together with the same part material, there’s virtually no size limit with FDM.

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