Help..Grinding aluminum and plastic

Date 06-10-2011 13:27

We all know (or should) not to use a grinder on wood, plastic, etc.
I need help with finding documentation prohibiting the use of a grinding wheel on plastic. I've spent a couple hours going through OSHA, and All I found was under Ship Breaking, advising against getting wheels loaded up with copper, aluminum and bronze residue.
OSHA Regulations (Standards - 29 CFR) 1910.215(d)(3) does mention "free of foreign matter". Even Norton Abrasives was no help.
The problem is, I'm dealing with Shade Tree Knuckle Skinners and since our "Uncle" has a proceedure that details the use of a grinder to perform this task, (so it's gotta be good right?), I can't get any cooperation. To support my argument, I need something that spells it out in plain English...Dangerous! Do Not use to cut plastic!
We have about 1100 linear feet of these cuts to make, so I'm trying to order a Craftsman Twin blade carbide cutter to slice through an aluminum plate glued to plastic. Frustrating because they (us taxpayers), are spending a Billion bucks a week over here and I can't get a $200 tool to do the job safely and right.

Any guidance will be greatly appreciated.

By Joseph P. Kane (****)

Date 06-10-2011 13:58

If it is just straight cuts on aluminum and plastic, just use an ordinary skill saw with carbide blades.

By Superflux (****)

Date 06-10-2011 14:16

If only it were straight cuts! A 10x12 cut out, with a "T" shaped section left in the middle. Inside a cramped vehicle cab floor board.

By rlitman (***)

Date 06-10-2011 14:55

> . . . advising against getting wheels loaded up with copper, aluminum and bronze residue. . .

There are grinding wheels made for use on aluminum. The big difference, is that they're loaded with much more adhesive, so aluminum cannot work it's way into the wheel.
I've used sanding discs, and a chainsaw disk on my angle grinder on wood. The twin cutter is a good idea, but I've heard bad reports as to their longevity.
A "kett" saw would be ideal for what you're doing.

By Superflux (****)

Date 06-11-2011 03:08

rlitman,
Is it the motor or cutting wheels that are short lived?
Speaking of longevity, how well do those chainsaw wheels hold up?

By Tommyjoking (****)

Date 06-11-2011 03:50

Superflux

I use those Norton grinding wheels made for aluminum rlitman is talking about ...I use them heavily as in gouging out cracks in 1/2 thick aluminum on a very regular basis...they do not explode like you would expect....they just grind away. I reckon since the plastic is bonded to the AL the AL would help keep the disc clean of the plastic...maybe. I would have no fear of trying it for sure. Carbide tip saw blades like a pirahnna will do the job but in a tight spot probably not a good idea. I think there are also some cutoff wheels made for aluminum but I would have to ask my supplier on that one. If you can get away with using a 4 inch grinder barring something better those Norton wheels should do it without drama I would bet. On that dual saw setup I have heard the saw gears/drive wear out fast with heavy use, have not used one myself.

Good luck with it
TOmmy

By rlitman (***)

Date 06-11-2011 04:51

Well I haven't tried one myself, but from what I read, the blades in a twin saw rub on each other, and need to be lubricated in the middle. Eventually, that eats the machine. Carbide itself should hold up very well in aluminum, or plastic.

I have the arbortech wheel, which sharpens like a chainsaw, but doesn't actually have the chain around the rim. I haven't worn it out, just the occasional touch up with a chainsaw file, but I use carbide burrs in my die grinders much more, so it hasn't see a great deal of use.

By Superflux (****)

Date 06-11-2011 09:12

Thanks all for the suggestions. The aluminum is not the primary concern, but the plastic in between. I've been mining through the internet and have yet to find a dual purpose cutter.
Does anyone know of a supplier/maufacturer of a 2" or 3" carbide toothed cutting wheel that mounts onto a 20K rpm pneumatic cut off tool?

By Superflux (****)

Date 06-11-2011 09:31

Conventional abrasive wheels just aren't "cutting it" (pun intended!). Tried the AL rated wheels, tried the 4" Diamond wheel. They both gum up and over heat. The plastic in there has really dropped a turd in the punch bowl on this. If it were just me, I'd have no qualms trying most anything. I have the scars and an foot thick Orthopedic file to prove it. I just don't want one of my men on my watch to have an overheated wheel come apart. Especially in such cramped quarters.

By 99205

Date 06-11-2011 14:49

http://www.micromark.com/24-Tooth-Carbide-Tip-Saw-Blade-3-1and4-Inch-Dia-10mm-Hole,7502.html

By rlitman (***)

Date 06-11-2011 19:00

Someone's gonna saw their face off using that carbide blade in a cutoff saw. WAY too much kickback from something like that to be used freehand.
This is exactly what a kett saw is made for. Cutting short (but relatively straight lines) through panels. It's like a pistol grip circular saw, with a tiny (under 2") blade.

By Superflux (****)

Date 06-12-2011 16:51

rlitman,

OK, that last post of your's got me to dig a litttle deeper. At first, all I saw was nibblers and shears, but I think the big rotary cutter is going to be the ticket. The 5.5 amp motor sounds to be a bit wimpy, but not all motors are created equal.
I want to thank everyone for their input on this. All suggestions were followed through, and as always, I knew I could count on my friends, colleagues and brother welders to help me out of a pinch.
John

We are winning the war against terrorism, one truck at a time.........

By rlitman (***)

Date 06-13-2011 14:26

Yeah, Kett makes lots of stuff other than these:
http://www.kett-tool.com/product.php?cat_name=Saws
Just like Dynabrade makes lots of stuff other than DA sanders, and Sioux makes lots of stuff other than angle drills. Maybe I should have been more specific, but here's to hoping that tidbit helps you out.
When I think Kett, that's what I think of. There isn't really much else like it.

By Superflux (****)

Date 06-13-2011 17:35

Thanks again,
I'm just trying to get the P/O approved now. You'd think I was asking them to donate a kidney...