Tooling suggestions for PVC

Discuss Thermwood 3-axis Machinery, Controller, and Software.

Moderators: Jason Susnjara, Larry Epplin, Clint Buechlein, Jim Bullis

Post Reply
Rob Davis
Guru Member
Posts: 351
Joined: Mon, May 23 2005, 5:43PM
Location: Indiana
Contact:

Tooling suggestions for PVC

Post by Rob Davis »

We are machining a quantity of PVC sheets for an industrial customer. i am using Vortex tools in upshear for most of the cutting operations (18000 rpm and feed 325ipm) and I am using a 2" flycutter for the surfacing part.
1) Are these the "best" tools for my application? Suggestions?
2) The "chips" melt together and I get balls of chips which are no big deal but tiresome. If I cut faster will they not get as hot or will they get hotter? Slower generates heat too fast and gets things gummy. I went up to 550ipm and while really loud, it was OK but seemed to be really working hard. (Lots of load on tool) I have been too chicken to run faster for fear of overloading the tool and busting it. The chips just hang around and don't get sucked out too easily as they get too big to go up tubes and cut down air flow.
3) Sometimes the upshear lifts the small parts so I was thinking of using straight or downshear for small parts but I am afraid I will end up with a big melted ball. I am tabbing the small ones for now to stay ahead.
4) Any other suggestions here would be great. Feed, speed, type of tool, things to watch for, etc. I have no trouble holding this stuff to the table!
Looks like we'll be doing this for a while so better fine tune it best I can and I am hoping the Forum can get me onto the right things to adjust without me using trial and error.
Thanks in advance!
Rob
Forrest Chapman
eCabinets Beta Tester
Posts: 1231
Joined: Mon, May 30 2005, 2:26PM
Location: Anderson SC.
Contact:

Re: Tooling suggestions for PVC

Post by Forrest Chapman »

Hey Rob,

I use a 3/8" upshear turning 15k rpm at 650 ipm in 1/2" material. It sounds like its tearing through the material but cuts well. Skinning all your parts and climb cutting will help with lifting.

Hope this helps,
Forrest
Rob Davis
Guru Member
Posts: 351
Joined: Mon, May 23 2005, 5:43PM
Location: Indiana
Contact:

Re: Tooling suggestions for PVC

Post by Rob Davis »

Thanks, Forrest.
Ryan Hochgesang

Re: Tooling suggestions for PVC

Post by Ryan Hochgesang »

You will have to work with Feeds/Speeds per your application but, I've had pretty good luck using a (3) flute low helix tool when cutting harder type plastics. The upward, low helix helps remove chips, but doesn't have as much pull on the part as a typical helical tool. Below you will find the woodworkers wholesale site with some sample tooling:

http://www.woodworkerswholesale.com/Sea ... elix+upcut
Rob Davis
Guru Member
Posts: 351
Joined: Mon, May 23 2005, 5:43PM
Location: Indiana
Contact:

Re: Tooling suggestions for PVC

Post by Rob Davis »

Very helpful. Thanks Ryan.
Rob Davis
Guru Member
Posts: 351
Joined: Mon, May 23 2005, 5:43PM
Location: Indiana
Contact:

Re: Tooling suggestions for PVC

Post by Rob Davis »

For closing the loop, I ended up cutting at 600 ipm for surfacing, 450 for contouring and the single biggest factor = sharp tools! I hd no troubles with this formula and are well on our way to running all these parts.
Rob Davis
Guru Member
Posts: 351
Joined: Mon, May 23 2005, 5:43PM
Location: Indiana
Contact:

Re: Tooling suggestions for PVC

Post by Rob Davis »

Update and maybe an opportunity for someone:
I am admitting defeat here. After one successful run, I have hit the wall. The surfacing of the stuff makes the sheet curl up on the table and come loose and then all sorts of bad things happen. Not every one, but often enough I don't want to be in the line of fire when chunks come out of the machine at bullet velocity. So if you can solve this problem, you can have the work.
Material is Delrin plastic and supplier gives sheets 22" x 35" and supposedly 0.250" thick but actually closer to 0.260 or 0.265. They need them surfaced to 2 different thicknesses, 0.225 and 0.218. I figured this was a no-brainer with flycut tool but not. I was down to taking 0.005 per cut and using a 2.5" flycutter going 450 ipm. And yes, I flycut the table to dead flat before I started, used a sharp tool, had plenty of vacuum, etc.
My opinion is the tool generates enough heat at the cutting surface to create stress in the sheet and as it cools and contracts, it pulls it up off the table. Not hot or warm to touch but this is my guess. Sheets "bow" up to 1/2" as you go across. I tried slower (less material might mean less heat genereated) and I tried faster (less contact time) and I tried heavier cuts and thinner cuts and just am out of ideas. This stuff is so dense and so strong and hard it is unforgiving.
The customer says they think I shoudl cut grooves in the spoil board and install seals where the parts will lie and then drill holes through board to maximize vacuum pull in this area. But this gets to really dedicated equipment and they only need a couple of these a year (100 or so) and I am reluctant to chop up my table when it is working so good for cabinet stuff.
So, if you have ideas or want to try it, you could post ideas on this forum or PM me if you want me to pass your name to the customer.
I am going to stick with fiber materials I think.
Rob
Michael S Murray
eCabinets Beta Tester
Posts: 933
Joined: Tue, May 17 2005, 2:48PM
Location: Logansport, In
Contact:

Re: Tooling suggestions for PVC

Post by Michael S Murray »

Rob,
How about this.

Take a couple pcs of 3/4" mdf slightly larger than you material size
Glue them together to make a 1.5" thick fixture.
Rout in a groove for a gasket, and then bore a through hole through this fixture and then a channel on the bottom of it, from the hole, then out the side.
Then suck this down using your big table pump.
Then use a small pump like they use on vacuum bags or vacuum holding fixtures, I have several here in shop.
This will hold a TON.
You can snap a 2x4 with my vacuum bag setup we use for veneer work..
Mike Murray
Versatile Cabinet & Solid Surface
mike@versatilecabinet.com
http://www.versatilecabinet.com
Post Reply