First step is to get a membership at TechShop! They have great classes and great tools! This was my third class at TechShop Chandler, where we learned about vacuum forming.
You can find more info at http://techshop.ws
Step 1: The Formech 686 - Key Controls and Connections
Material size 27 x 26"
Forming area 25.5 x 24.5"
Max. depth of draw 12.8"
Max. material thickness .25"
Controls on the front of the machine are used mostly during the actual forming process. Times, temperatures, table control, etc.
Controls on the back are for power and air pressure.
Our instructor referred to the process of vacuum forming as "pulling". Making a part is called "pulling" a part, or making a "pull". The master shape that you use to make your part is referred to as a mold, or buck, or form. I refer to it as a form in this Instructable.
Step 2: Reducing Windows, Mold/Buck Placement, Material Placement
Our instructor gave us an overview of the machine and it's controls before turning it on using the master power switch in the back of the machine. Once on, he used the front panel control to turn on the heater system so that it could warm up.
While it was warming up, he explained how the heater rolls in and out as needed. Also explained were the reducing windows. These are important for reducing material waste. If you have an 8" by 8" part, use the smaller windows so you don't waste so much material. Use the larger windows as needed.
Form-making is pretty involved. The instructor made one prior to class that we all used. It's important that you don't undercut the edges on the form, or it could get trapped in the formed part.
The table that holds the form is inside the middle of the machine. It raises the form up into the softened material, which is then pulled down around the form to get it shape. You have to raise the table to place your form, and to make the "pull".
Step 3: Heating Your Material, and Making a "pull"
So you have the machine connected, warmed up, have your form placed on the table and centered, and have your material clamped down in the reducing window. Now you need to heat your material. Each material has different thicknesses and heat related properties, so this takes a little more attention and care. You want to get the material soft enough so that it stretches and forms, but not so hot that it sags too much or tears during a pull.
This particular machine has a anti-sag feature, where it monitors how far the material is drooping. If the material gets too low (too hot) it puffs a little air at the material to raise it and cool it. It's best though to watch it and catch it before this happens.
There are a couple of things to look for, and you can watch the material as it warms, by looking through the gap between the heater and the reducing window. There are some pictures below. Look at the reflection on the material to see how it changes as it warms up.
Step 4: Releasing the Part
Once the material has cooled, you'll want to release it from the form. Our instructor had a cool little infrared laser thermometer that he used to see if the part was cool enough to release. You need to wait until the material is cooled to a point where it will hold it's shape. If you don't let it cool, some of the shape and definition might be lost.
Use the control panel to send a puff of air to separate the form and pulled part, then unlock the reducing windows, and raise them out of the way. You can now lift your pulled part and the form out of the machine. Lower the table when you are done, so that it is out of the way.
Next is to remove the un-needed material. Our instructor used the laser cutter to do this, which left a nice clean edge. You can use just about any cutting device.
Be sure to clean up and shut down if you are done!
Step 5: A Few Additional Notes...
Our instructor wanted to show us some of the bad things that can happen while making a pull. So we overheated a piece of material during one pull. The material was too soft, and tore during the pull, this cause the vacuum to be weak and the part did not fully form. See the picture for the result.
All in all this was a great class. Cannot wait for the next one. Thanks TechShop!