Thermoforming Wisdom from The Ancients


Confucius said, “By three methods we may learn wisdom: first, by reflection, which is noblest; second, by imitation, which is easiest; and third, by experience, which is the most bitter.” We all know the internet has increased the pace of most things in life, but perhaps finding the path to wisdom is also easier today: just take the bus.

Alas, the pace of modern business is not necessarily conducive to ample reflection time, and wisdom gained through imitation can run afoul of copyright or patent laws. Are we forever doomed to the bitter wisdom of experience? Or do we simply learn best from our mistakes?

We will include ‘repetition’ in this 3rd category. Just because you have a strong case, it doesn’t mean that everyone will accept your argument immediately. Any salesman with the newest, fastest mousetrap will tell you this. So it does behoove us to refine the message and frame it in the context of what matters most to the customer.

Over a period of 12 months, CMT engaged with toolmakers and others to truly understand the optimal method for cutting and machining syntactic foam. Simply put, it is not like other materials. It requires a different approach and different tools.

The CNC programmer must understand both the nature of the material and the optimal feed rate so the machine operator can use the correct tool geometry so that the plug fitter (usually the person who is tasked with getting the smoothest surface possible) does not have to wear his fingers out during polishing.

And while we can easily provide a short list of key concerns, making the leap from, “Yes, I understand. Let me get this to my team” to “My team followed your guidelines and we have solved all of our problems!” is not easily achieved.

So, in the spirit of sharing our bitterly-acquired wisdom, here are the main points to remember when machining HYTAC syntactic foam for plug assist:

1. Use sharp, solid carbide tools that are designed for cutting abrasive plastic. Not metal. Not wood. Talk to your tool provider.

2. Keep the heat out of the tool. We know people use coolant, but it is not required if the feed rate is accurate. If the tool is too hot, it is either dull or the feed rate is too slow.

3. Understand the variables of the feed rate: RPM x number of flutes x chip load. A little bit of trial and error will ensure that you get it right for your project. The goal is to get the best possible surface finish.

For a more in-depth discussion of machining, download Module 3 in our Learning Series. And, as always, get in touch to let us know what works (or doesn’t) for you. We’ll all be the wiser for it, with a bittersweet aftertaste.