Routing Phenolic.. Chilling Coolant Air?

[Brian Mifsud]

Hi All,

First post. I'm a Mechanical Engineer. My Dad was a Machinist (non-CNC.. "old school" mills and lathes...) so I understand speeds and feeds and holding parts for rigidity.. all the basics. I'm faced with a situation where we CNC route 5mm Phenolic Sheet in fairly large volumes. Supplier "A" provides a reasonably machinable material where we can get several hundred parts (about 6 linear feet of cutting per part) per cutter before we need to change out. Supplier "B" provides a much "harder" material, at a substantially lower price point, but so far, we've destroyed our carbide cutters (3 flute, slight spiral, starts with plunge cut) in a few parts.

Big pressure to see if "Supplier B" material can be utilized. I'm NOT sure that we've optimized the cutter shape, nor speeds and feeds, but I know for SURE that Production will not tolerate longer cycle times.

So back to basics, our Thermwood and Routech CNC machines use vacuum to remove chips, but there is no active cooling. Coming from the metalworking background point of view, I see the absence of coolant as leaving lots of tool wear on the table.

Has anyone any experience applying chilled air as the "coolant" in machining Phenolics? It's nasty a horrible heat-holding material. Would this make any substantial difference pulling heat out of the tool or are things moving too fast to make a difference?

Thanks

[Steve Jenkins]

I can’t speak to phenolic but I know that adding a “cool gun” from MSC when milling 100’s it feet of oak and maple rope molding increased time between sharpenings about 10-15 times. I was using a porter cable router on a Legacy Mill

[Jim Becker]

Many phenolic products are very abrasive so you may need to use a specialized cutter rather than a more traditional end-mill. Amana has some as do other major tooling manufacturers.

[Grant Wilkinson]

The shop where I work part time does a lot of corian work on a Biesse. I realize that this is not phenolic, but it, too, holds heat. The boss found bits that are a tighter spiral than a normal end mill. They cut cleaner and run cooler. He says that their life span is much better, too. The bits' specs say that they are designed for this material, so I expect you will have little problem finding them.

[Dave Sheldrake]

Have a look at fast helix ripple cutters designed for plastics and light aluminum, Close grain carbide will work well and don't suffer with heating as much.

Air amplifiers can give a good blast of cold air for cutting without the need for commercial cooler units

[Ted Reischl]

Make sure if you blast air into a phenolic cut that you are NOT blasting that dust into the air you breathe. Machining phenolics and breathing the dust has been a known carcinogen for over 50 years. I worked at Spaulding Fibre in the 70's in a factory that primarily machined phenolic and glass fiber products. We were very careful to not let that dust get into the shop air as it was already known that it caused lung cancer.

[Rick Whitehead]

I had to cut some 1/2" phenolic sheet once. I used a PCD cutter made by Amana. It cut the phenolic just fine. I only had a few cuts to make,so I don't know how long the cutter would have lasted in production, but I'm sure it would have outlasted solid carbide.
If you get your speed and feed right, you shouldn't need coolant.
Hope this helps.
Rick W