Thermoforming high volume Lexan parts
Submitted by Gary Pettet on Thu, 01/21/2010 - 3:48pm
I am fairly new to thermoforming and plastics processing in general although I have been a Manufacturing Engineer for many years. We have been thermoforming Lexan 6000 material and doing the trimming on 3 and 5 axis cnc routers. My problem is tha up until lately most of the parts that I have made form tools for have been prototype or very low volume parts. Most molds are made from a Urethane rapid prototype material. This works well for small runs of parts and trim fixtures but I am having trouble using it for our high volume part runs. I am now considering using an epoxy board type material or aluminum tooling. I am steering more toward the epoxy because of the heat dissipation. What I would like to know from some more experienced plastics engineers out there is if this is the right track to be on or should I be look at aluminum tooling with a Thermolator or something to stabilize the heat instead. Any help will be greatly appreciated.
Comments
Tried this
You could contact www.mayfieldplastics.com as I have found them to be helpful regarding thermoforming questions.
Mold material
We use both materials for molds. They each have a few advantages.
The Urethane retains the warmth for less chill lines, however the material can become less rigid and has the possibility of fracturing. Cool times and draft angles can help to nullify these issues.
Aluminum deteriorates less and we actually have an aluminum mold that we have been using consistently for over 2 years on large part runs. As you said, the heat dissipates quickly and this can cause bowing. If you can keep the part cycles short and control the mold temperature this can also be controlled with consistency.
All of this said, I would advise the aluminum if you are going to be making large part runs and want to avoid some of the time stealing of repairing a possible Urethane mold.
Aluminum Molds
Thanks for the comment and help. On your aluminum mold, what do you use to control the temperature. Do you control your cycles somehow, or do you have some type of coolant circulation such as a thermolator to control it?
Thanks
Gary