Field Notes: National Hands-On Thin Gauge Thermoforming Workshop

By Terry Woldorf, General Manager, CMT Materials

“Highly interactive.”   “Informative.”  “Surprising.”  “Great combination of lab, lecture and science and fun.”  These are just a sampling of comments overheard at the 4th annual National Hands-On Thin Gauge Thermoforming Workshop.

CMT Materials, Inc. again was invited to present in the lectures and participate in the lab.  The three day course equally balances classroom instruction time with hands-on lab time. The workshop covers a wide range of planned topics but also intentionally allows for flexibility to cover unplanned topics raised by participants.

The workshop takes place each year at Penn College of Technology campus in Williamsport, PA and is part of their Workforce Development and Continuing Education program in the Plastics Innovation and Resource Center (PIRC).  Attendees from as far away as Wisconsin, Florida, Texas and Michigan mixed with others from nearby states to fill the roster to its cutoff capacity of 30 people.  Keeping the group small ensures instructors and guest speakers are able to interact and fully explore topics, effects as well as the inevitable surprises from process-related matters in the extrusion, thermoforming or testing labs.

Hosted by Chris Gagliano, PIRC Program Manager –Thermoforming, and instructed by Mark Strachan, President of uVu Technologies, lectures included:

Dr. Kirk Cantor (Penn College):                   “Raw Material & Sheet Extrusion for Thermoforming”

Mark Strachan (uVu Technologies):          “Fundamentals of Thermoforming, Advanced Thermoforming Techniques, Trimming and Stacking”

Robert Wandelt (uVu Technologies):        “Thermoforming Quality Control and Process Monitoring”

Julie Griswold (WR Sharples Co.):              “Structural Design Considerations When Building Steel Rule Trim Dies”

Terry Woldorf (CMT Materials):                  “Plug-assist Material Selection, Geometry, Processing Methods and ROI Calculations”

Robert Borse (Angle Tool Works):                “Tool Design”

Dr. Joseph LeBlanc (Penn College):             “The Physics of Heating and Cooling the Sheet”

Bill Norderer (Raytek):                                     “Thermal Imaging Tools and Techniques”

These topics combined with multiple break-out group lab sessions where participants ran equipment, tested new and old procedures, interacted with each other, students and full-time PIRC employees. Participants generally tried to prove/disprove a wide variety of theories and traditional “best-practice” approaches to the thermoforming process.

If you missed out on this year’s event, be sure to contact the school to sign up next year.

Field Notes: Kiefel USA Thin Gauge Thermoforming Workshop

By Conor Carlin, International Sales Manager

On June 27-28, CMT participated in an impressive thin gauge thermoforming workshop hosted by Kiefel Technologies USA at their facility in Portsmouth, NH. The event was a highly technical affair with presentations from a variety of experts as well as a demonstration of a KMD85 inline thermoforming system. Attendees and participants came from both sides of the Atlantic including Germany and the Netherlands, New England, Canada, Ohio, Michigan, Wisconsin, California and Florida.

If any single theme emerged from the two-day event, it was that new technology has most certainly impacted the thermoforming process. The increased adoption of fast-cycling, tilt mold machinery means that tooling, including the plug assist, must be exceptionally precise and engineered to very tight tolerances. The use of air-save technology is just one of the new innovations in thermoform tooling. On the topic of air consumption, Kiefel explained how new high-volume, dual circuit pressure forming valves allow air to flow in and out of the mold cavities for faster cycle speeds and a significant reduction in air consumption and, by extension, operating costs.

The application of information technology to thermoforming is proving to be a rich vein of conversation in the industry. As demonstrated by Sam Hacman of uVu Technologies, real-time visualization of data from multiple monitored points (strain gauges, temperature sensors, plug drive sensors, vacuum/pressure transducers) can now allow operators to truly understand the variables in the forming process, further removing the moniker of ‘black art’ from thermoforming.

Here is the list of speakers and topics:

Julie Griswold – Sharples: “Structural Design Considerations for Steel Rule Die Applications”

Conor Carlin – CMT Materials:  “Best Practices for Using Syntactic Foam Plug Assists in Thermoforming”

Frank Karai – ODC Tooling:  “Tooling and Challenging Applications”

Michael Walper – Hekuma:  “T-IML Automation: Technology Ready for the Market”

Martijn Haex – Bosch Sprang: “Advanced Tooling Technology for In-Mold Cutting”

Jeff Nigro – Klockner: “New Product Innovation”

Markuz Zlotosch – Kiefel Technologies: “Advantages of a Speedformer”

Todd Morgan – Ametek LAND: “Scanners for Thermoforming Applications”

Brian Golden – Kiefel Technologies: “Beyond Conventional Wisdom”

Sam Hacman – uVu Technologies/ToolVu: “Thermoforming Quality Control and Process Monitoring”

Thomas Huber – Kiefel Technologies: “CAT System Presentation on Kiefel KMD85B”

Our presentation on plug assists began with a live poll of the audience to determine the percentage of tools that were manufactured with plugs. A second question explored the different types of materials used for plug assist. From the responses, it appears that syntactic foam is the leading choice of thermoformers and toolmakers. We dug further into why it is important to understand the interplay of the plug material, plug geometry, tool design and sheet temperature, and not just to look at each element in isolation. While the choice of plug assist material directly impacts the plug life, machinability and ease of processing, it is also directly tied to material distribution, cycle time, start-up time and process cost.

In addition to bringing together industry experts and processors for a great seminar, the Kiefel team also proved to be generous and thoughtful hosts. We were treated to a tour of The Redhook Ale Brewery and a traditional New England lobster bake for dinner! Here’s hoping they make this an annual event….

How Syntactic Foam Plug Assists Improve Your ROI

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.

“Which Syntactic Foam Should I Use?”

We are often asked to provide recommendations on plug materials based on a specific project. Usually the processor will ask us, “Which material should we run with PP/PS/ PET, etc.” And while we are happy to engage with toolmakers and thermoformers, there are many elements beyond our scope that need to be taken into consideration. However, we strongly believe that using the right material under the right conditions can make a dramatic difference in the end product.

The following is our response to a typical customer inquiry. We are writing about in our blog today because it is a universally relevant response. As always, we would love to hear from other processors who have different experiences. (All names are changed or removed to protect the innocent!)

“In this [PP cup] case, I think the answer is simply to have your customer reduce the temperature and fine tune the process.  PP has a very narrow window for forming temperatures and the range your customer is at is very high.  This is common when the customer has past experience with DELRIN due to the high thermal conductivity of DELRIN, which takes heat out of the sheet very quickly so the PP must be run at higher temperatures. (The thermal conductivity of DELRIN is over 2000% higher than XTL!)

While FLX and XTL will provide suitable performance, XTL will hold up better to abuse in the process.

Several factors that may help in the comparison of materials:

  • XTL, FLX and DELRIN all have the same service temperature of 350F/176C.
  • Thermal conductivity for each material (which controls how fast the material absorbs heat from the sheet ):
    • XTL: 0.17 W/m0K  (0.10 BTU/hr-ft-0F)
    • FLX: 0.11 W/m0K   (0.065 BTU/hr-ft-°F)
    • DELRIN: 4.32 W/m0K  (2.497 BTU/hr-ft-°F)
  • Thermal expansion for each material (which controls how much the plug expands as it is heated):
    • XTL: 58 x 10-6 m/m/0C (0.000058 m/m/°C)   (32 x 10-6 in/in/°F)
    • FLX: 42 x 10-6 m/m/0C (0.000042 m/m/°C)   (23 x 10-6 in/in/°F)
    • DELRIN: 85 x 10-6 m/m/0C (0.000085 m/m/°C)  (47 x 10-6 in/in/°F)

The true meaning to the application of the numbers above comes from realizing that thermal conductivity has a double impact.  First, the higher the number, the faster heat is absorbed from the sheet.  (This results in the need to run the material hotter than is recommended and results in “chill marks” that show where the plug contacts the sheet. It also means the process typically must run slower to allow time for the sheet to form.) Second, the higher number means the plug itself will absorb heat faster, which means it will expand more quickly. (This results in the need to run more pieces at startup to allow the plug to stabilize in temperature and size.)

For thermal expansion, the higher the number the more the plug will expand as it is heated.  This means the user must start with a plug that is smaller at room temperature than is needed for best material distribution.  Many pieces must be run to stabilize the plug as it expands over time.

If you focus strictly on the numbers though, it would indicate FLX is the best choice.  FLX does work very, very well with PP and we often recommend it.  In the case of your customer though, you can see from looking at the plugs that there is much material buildup.  This generally results from running the sheet at too high a temperature creating a buildup of melted plastic on the plug. The scratch marks and chipped- out sections indicate the material has been scraped or chiseled away from the plug and damaged the plug surface.  In this case, we would suggest XTL is the better alternative because it is so much tougher and more resistant to chips and dings.

If the customer turns down the temperature (even a drop of 5 degrees will help) the parts will run better, they will likely be stronger in crush strength and the material will not stick to the plugs.”

Needless to say, our email exchanges can be very in-depth, but we wouldn’t have it any other way. Got any questions on your own application? Let us know by filling out our basic form here.