We all know that handmaking a mold is a long process that can sometimes be tedious and very frustrating.
I’ll show you that (sometimes) is better to spend some time in front of a Pc rather than covered in dust, and the result will be amazing!
I have been through the process of building the master plug for composite mold making and the majority of the time, for large objects, it’s the only affordable solution.
For smaller and more precision-demanding molds, I’ts fairly easy to obtain a nicely finished plug ready to make the mold from, and here it’s how it can be made.
Of course, the first thing to do is to have the 3D CAD file that will be used to machine the plug, this could be easily achieved by downloading already-made models or by designing your specific part using 3D modeling software.
Once we have our specific 3D model we can import it into the CAD-CAM software that will convert our design into machine codes to run a CNC mill.
In the CAD-CAM software, you will have to “place” your model into the working material and set the working parameters as tool dimension, feed, spindle speed, etc…
Now that we have the right code to run the machine it’s time to load the material on the mill and start making some chips.
There are a lot of materials that can be used to obtain a plug such as plastics, wood, or aluminum. When it comes to composite making there are materials specifically created for this particular application. Those materials are called tooling boards and are made out of high-density polyurethane or epoxy (for CNC machining a density of over 500 kg/m^3 is required).
You can learn more about the topic here: https://explorecomposites.com/articles/tooling/machinable-tooling-boards/
Tooling board machines similar to MDF (always take precautions against the dust) and once you have finished your machining it’s time to make the plug shine!
Again there is a product generally called board sealer that helps us to seal the holes of the board obtaining a perfectly smooth and shiny surface, all we have to do is lightly sand the plug before applying liberal coats of this product (sanding between the first applications)until we obtain a perfectly smooth surface.
We now can treat this as any other plug: applying release agents and then building the composite mold above it.
Properly sealed tooling boards can be also used directly as a mold for small batches of production.
The tooling board and the sealant can be easily found here https://www.easycomposites.eu/ or at other composites material vendors.