Understanding the interaction and balance among plastic sheet, plug material choice, plug design, mold design, plug speed, vacuum, form air and numerous other factors often separates true artists from lucky amateurs. At CMT, we like to talk about the interplay of all of these factors as the plug meets the plastic: the point where the action is most immediate in the thermoforming process.
While there is often no single choice to be made, making the “best” choice reduces machining costs, improves material distribution, enhances clarity, reduces plastic residue sticking to the plug and maximizes plug life. Introducing science to the process allows even unlucky amateurs to become thermoforming artists.
Many machine operators know the stress of trying to meet production goals while maintaining quality standards. Running large machinery with precise tooling means that you’re in charge of some serious operational assets. You don’t always have the time to stop and appreciate how ROI is calculated or what you can do to improve it. However, stopping to think about the role that the plug plays in your process can save some serious time while you’re reflecting on machinery, tooling and material.
The following comments came from a thermoformer who participated in one of the recent workshops where CMT was invited to speak. We think it provides excellent insight into the daily challenges faced by operators and how a small change can have an outsized impact.
“I took what was learned in your class concerning material flow over the plug assist and applied that to the design of our mold. I started with 1/8” offset from the cavity, applied blends in strategic areas based upon my new understanding, and had the tool maker polish the HYTAC FLX plugs to a 1500 grit. These three things together resulted in a wall thickness that was more than double what we had seen in the part’s troubled areas.
I’ve only been involved with this project for a relatively short time (8 months or so), however, I know that over the years (several years, in fact) at least two engineers and a host of operators and tooling people have all tried their hand at carving assist plugs, adding on to the mold length, and various other forms of ‘black art’ in the attempt to thicken up those troublesome thin walls. In short, the training we received from you proved that there is more of a science to thermoforming than most people recognize.”
CMT will be co-leading a thin-gauge thermoforming seminar at the upcoming SPE Thermoforming Conference in Atlanta, GA on September 9-12. Titled, “Mythcrushers”, we set out to separate myths from facts in thermoforming. We’re looking forward to an interactive and dynamic conversation.