Thermoforming
Formech manual and thermoforming guide PDFs are available for download on the wiki (linked above).
There is a gasketed frame on our Formech that will seal a 24x24 inch piece of sheet plastic for vacuum forming.
We sell 1/16 inch sheets of clear PETG (listed on the materials page) for this, but you can bring in your own.
The sheets must fit the frame for an airtight seal, for the vacuum/compressed air in the machine to work.
On the manual operation page, there's a sequence of buttons that more or less walks through the steps.
Understanding these is easy with a little practice, which will happen in an in-person training session.
Access to the machine will involve going over these steps in person, and practicing at least once.
We can provide one sheet of plastic for this.
After that, students are free to use the machine as long as they:
-
do not put any dusty, dirty, crumbling, greasy or wet material in the machine - debris will clog the air lines, and the
machine will need to be dismantled for repair.
- do not ever pull the heating elements over a sheet that is not flat - if anything touches them while they are
hot, they will burn, be damaged, and require expensive repair/part replacement.
- do not leave the machine open (without a cover) after use - a cover needs to stay in the frame to keep the
interior and the air lines as clean as possible.
Plastic can be vacuum formed or manipulated manually, as long as it's not destructive to the machine or
the user.
Unintentional wrinkles happen, usually with overstretched plastic, and tall corners like these:
Soft or weak tooling will also deform under the vacuum - these were pointed tips, originally:
Testing must be done to determine heating time for good quality, which will change depending on plastic
type, thickness, tool geometry, and even whether the machine was started at room temperature or if it was
still warm from previous use before testing. The sheet is watched carefully as it heats - it deforms first:
and then it sags:
minor surface texture on a tool will show up in the plastic:
This one was heated until it sagged/stretched a bit too much:
This little port in the center must be kept clean and clear for vacuum - the mesh is necessary to prevent sealing:
Also note the 2nd gasket around that plate - be careful not to damage that foam, either.
We need to prevent dust and other mess like this stain from happening inside the machine:
The frame is counterweighted, so be careful when you release the clamps to hold it so it doesn't
swing up towards your face:
When you pull the heating elements forward over the plastic, the clearance is absurdly tight:
and it can catch on the bolts on either side - so pull slowly, and expect to need to shift it a mm or two
in both directions to slide past those bolts.
This tool (mdf, below) was not made for thermoforming - the rectangular edge doesn't have draft angles (a slight taper)
and was very difficult to remove from the plastic afterwards.
If the sheet is not warm enough to form, it will pull - it can get yanked right out of the gasketed frame,
which can damage the foam we need to keep an airtight seal: