How Vacuum Formed Molds are Made.

A quick lesson to give you a rough idea of how it is done.

I am going to try to tell you in as few words as possible, how vacuum formed molds are made.

The first step is making the "buck".  This is the name of the piece that the forming will be done over.

This has to be smooth, strong, heat resistant, and free of undercuts.

The smooth part is self explanatory.

The strong part is so that it will not be crushed when the plastic is being formed over it.

The heat resistant part is because the plastic is at about 300 degrees F.

And no undercuts is so that you will be able to get your piece out of the mold without  having to cut the mold off.

All these are of equal importance.  They all must be done, and done right!

This is the time consuming part of making the molds.

Once this has been done the buck is placed on he table of the vacuum forming machine.  I put a light coat of Talc (in the form of cheap baby powder) on the Buck to help the mold pop off once it is formed.

This machine is the costly part of making molds.  It makes it possible to evenly heat and then mold the plastic.  The bigger the molds you require, the bigger the machine you need.  They go up in price according to the size of the plastic that they can handle. 

The machine has two basic parts,

1 - The heater - it controls the temp of the plastic within the range determined.

2 - The vacuum pump - it sucks the air out from under the sheet of plastic when it has been brought down to the vacuum table.

The blank piece of plastic is clamped into its frame and heated.

As soon as the plastic has reached it flow temperature ( I judge this by quickly touching it - if I can't hold my hand on it for more than a second it is hot enough) it is pressed down onto the buck and vacuum is applied at the same time.

The plastic forms over the buck and cools.   This takes about 3 or 4 seconds!  

Once it has cooled (about 30 seconds) you pop the buck out, take the plastic out of its clamp frame and trim out the mold!

That's it!! 

Copyright © 2005 Delmar Germyn All Rights Reserved.