Molds

Goal of this page is to discuss the different type of mold possible for composites manufacturing (pros, cons and the process for manufacturing each mold).

Types of molds

MDF (Illegal not allowed by SSDC)

• Making Composites Tooling with MDF

• Process:

  • CAD model is created and validated

  • Sponsor search begins

  • MDF block to be machined is glued together (epoxy) to prep for machining

  • Assuming sponsor has been found, deliver the blank to the sponsor

  • After machining is complete, return the MDF mold from the sponsor

  • Surface prepping begins:

    • Sanding the general surface to get it smooth enough for panel lay-up

    • Fill any holes using surface filler

    • Repeat sanding and priming process until a smooth surface is achieved

  • Apply mold release

• Pros:

  • Heat resistant in the off chance prepreg or thermoforming is used

  • Previous knowledge from MSXIV

• Cons:

  • Have to go through the process of finding a sponsor to do the machining for us

  • Heavy molds, typically require more than one person to move or a lift

  • Messy machining, leaves large chunks of MDF around after initial machining

  • Surface finishing requires more effort than that of a foam surface; sanding eats away at foam much faster

  • Higher cost than that of foam where a 4' x 8' x 5/8” sheet comes in at $66.91 (https://www.homedepot.ca/product/hdg-premium-5-8-inch-x-49-inch-x-97-inch-mdf/1000167403)

Foam

• Process:

  • CAD model is created and validated

  • Email the CAD file to Brian, the machinist

  • Foam blank to be machined is glued together (epoxy) to prep for machining

  • Block is machined in house

  • Surface prepping begins:

    • Coat the mold in a thin layer of epoxy resin (plaster and putty can also be used)

    • Sand the general surface to get it smooth enough for panel lay-up

    • Fill any holes using surface filler

    • Repeat sanding and priming process until a smooth surface is achieved

  • Apply epoxy coat on the final surface to prevent any resin placed later from seeping through the pores of the foam during layup

  • apply mold release (PVA and wax work well)

  • https://diyblog.commonfibers.com/blogs/process/plug-finishing https://www.generalplastics.com/wp-content/uploads/2018/08/General-Plastics-Tooling-Molds-Guide.pdf

• Pros:

  • Brian, the machinist, is willing to machine any of the MSXV molds in house so long as they’re made of foam (2 day downtime compared to looking for a sponsor to get a single mold machined)

  • Lightweight molds, can be easily carried by one or two people (even the larger scale molds)

  • Sanding surface is much faster than that of MDF (although can be a downfall of the foam if not careful)

  • Lower cost than that of MDF where a 4' x 8' x 1” sheet comes in at $43.50 (https://www.homedepot.ca/product/owens-corning-foamular-codebord-xps-insulation-48-inch-x-96-inch-x-1-inch-ship-lap-edge/1000155125)

  • Does not tear off in chunks during machining, and if it did, expanding foam can be used to re-fill that removed section? (assumption)

• Cons:

  • may be leaky (need to treat with chemicals in order to be able to tacky tape to the mold itself)

  • Rather porous and will need epoxy to prevent any resin during a layup from seeping through

Fiber Glass

• Requires a foam plug

  • Creating the plug entails the same process as a full foam mold, so going straight to the foam mold might be time efficient

• Ways to make the foam mold include:

  • How to Make A Fiberglass Mold from a Plug - Part 1 (foam glue together, cut, sand, apply fiber glass, sand, apply putty/plaster, sand, primer, apply mold release PVA and wax work well)

• Adding fiber glass onto the foam molds might be a good way to improve the surface finish and make the mold less leaky (plus we have a lot of fiberglass).

• Pros:

  • potentially less sanding (less time maybe)

  • mold is reusable

  • better surface finish than just a foam plug

• Cons:

  • more material

  • more expensive

  • will still require sanding the foam

  • more time (maybe)

Aluminum

• Process

• Pros

• Cons

3D printing

Hand Laminating a Carbon Fibre Part Directly into a 3D Printed Mould

Thermoforming Molds:

https://www.empirewest.com/thermoforming-mold-design-and-materials.html

How to build a vacuum forming mold to make your own plastic parts

Fiber glass, wood, aluminum, and foam all see to be viable as molds.

Are we planning in house or sponsor?

Additional resources:

Foam Molds