Cut-Off Wheel Competition/Question

Question, as briefly as possible...

We are a mechanical piping contractor, and use 6" cut-off wheels with angle grinders more than other other consumable/tool. With that, we have set out to find the best wheel in a all the lands. We have set up a testing station (gravity-fed, no human interference, etc) for phase one of the testing. We have roughly 40 different wheels in the 'competition' thus far, from virtually every mfg I could get my hands you. You name it, were likely testing it.

Well things were running smoothly at first, while cutting our first choice materials to cut- cs pipe. Some wheels did great, some failed terribly, etc...and we were really getting some good data to later crunch to find a good wheel at a good price-per-cut etc...Then....a mystery began.

We switched materials, and found that each wheel...either good or bad...performed exactly the same on each different type of material. It's hard to explain....try this...

Wheel A gets 10 total cuts (until wheel is used up completely) on:
3/4" Pipe CS SCH80 A106

Same wheel then gets exactly the same amount of cuts on:
1" Round Rod CS 1018 CR
1" Round Rod SS304
1" X 4" HHBolt GR8

HOW is this possible? With such wide ranges of the specs for each above, how does one cut-off wheel perform equally on all?? The Grade 8 bolt, for example....one would think would eat up a wheel much quicker than the cs round rod. Nope-same.

We decided to test this further....using a wheel that did a little better in the first round, 25 cuts on the pipe. Well, low and behold, it got EXACTLY 25 cuts on the other materials as well.

So.....can someone explain to us why this is? The only theory we have is that the abrasive blade is turning so fast, so hot, and with so much aggression, that it "over-rides" any work hardening rates or material composition in the metals...??

Thanks

Probably because the range in hardnesses between your materials pales in comparison to the wheel media.... by orders of magnitude. I suspect that the performance differences you are seeing are in the bonding matrix, not the actual abrasive material.

I'm no expert, just a guess.

I have been to a bit of a seminar on cutting abrasives here help by Lukas abrasives who are in direct competion to Pherd. The 2 seem to have a decent working relationship here because the Lukas guys admitted where their product was inferior or where it outshone the pherd product. Now interestingly enought they said that coating did not really play a bit part in wear but it was more of the bonding process. And I saw their test machinery to test just the thing that you are describing. The research guy told me that after wear on your wheel/disc that the R.P.M had a big influence on the life of the wheel/disc because the surface speed was way too slow. So I'm thinking that maybe at a certain OD on your tests that the wheels start wearing down the same amount because of the lack of surface speed.

check the area of the cross section that your cutting. I'll bet that you'll find that the area (leading to volume if you consider the width of the wheel) is all about the same. With the wheels that are available today, the cutting media is so hard, that the little difference in you material is not significant. Try cutting 1" Inconel with the same wheel.
JR

I think ...

I agree that the wheel is much harder than any of the materials.

I think that it simply has to do with the dia. of the wheel. Each revolution removes "X" amount of material from the wheel and "X" amount of material from the work piece.

More-bigger wheel = more-bigger life

Use a diamond x:

Abrasives - Grinding & Cutting | Grinding Wheels | Edmar 7" Diamond X Cutter Thin Disc Type 1 | B836831 - GlobalIndustrial.com

So.................how did Klingspor do in the test.

A user wants to know

Please post your findings.

I would suggest the test on some smaller square and rect. tubing, I think you will see alot different results. Mike

Thanks for the input.

So were saying that the hardness of the abrasive cut-off wheel is much harder than the test pieces. Meaning, the test pieces (though wide-ranging in hardness) are no match for the hardness of the wheel...and each wheel equally. Interesting. And all the text pieces are roughly 1" OD, and all the wheels are 6" OD, so that covers the cross section and grinding surface aspects as well. Still...that grade 8 bolt is about twice as hard rockwell and tensile as the cs rod...I wonder how hard a piece has to be to make a difference? 3 times? 4?

I'm going to test that theory a little. Just bought a piece of 1" OD M2 Tool Steel from McMaster, will be here tomorrow and report back. That stuff looks pretty damn hard, so we will see. I also bought a piece of 1" OD Aluminum 6061 just for fun. I might assume since it's soft, it will get a better wheel life..?? Probably not, for some reason I'm thinking it will eat up a wheel for some strange materials reasons. Will report back on that as well.

Brands. You got me on those...I have missed the Lukas and the Klingspor...both on the way now. On that note, please see the following link. It's a simple doc that lists what we have so far. If anyone can look through and suggest something else I missed, please post back here and I will certainly try those as well. Once all the results are in, I will report back here and post them, just for fun and information. Probably be a couple more weeks. Thanks again, and any other feedback is appreciated.

Link:
https://docs.google.com/spreadsheet/ccc?key=0AvFsDgmkMscMdE1Od2xkWW5oMnplbzNzYU43VlZIa3c&usp=sharing

Did you use a non contact tachometer to check speed on all your cuts, did speed vary on different materials.

Friction sawing heats the work quite a bit, but something that cannot be annealed by the cutting process might be interesting, HSS for example. Friction saws seem to do just fine on HSS though.

for a 6" wheel with a 7/8" arbor i use Norton wheels, they have 3 different grades, they work great, for 4" wheels with a 3/8" arbor i use Walter ZIP .035 wheels. Ive found those two to be the best of the brands ive tried. from my experience nothing wears out any type of cut off wheel faster than vibration in the work piece. Im very interested in the results of your testing as well.

My only thought is to be careful with the aluminum, it may load up the cutting wheel and then do bad things.

duckman said:

Did you use a non contact tachometer to check speed on all your cuts, did speed vary on different materials.

Click to expand...

We're not that technical around here. But to be fair as possible...we have used 2 grinders of the exact model, swapping off and on, to keep on track with fairness of same speed, power etc for all wheels. Also, each work piece is positioned exactly the same on the jig, same size, same angles...etc, also, to try and be fair for all.

Apparently Lukas have brough out a cut off wheel here that out performs anything else speed wise. I'm not too sure if it is viable price wise compared to other brands. And last I heard Klingspor and Lukas have gone into partnership in Germany.

Did you measure the time required for each of the cuts for a comparison of wheel to wheel? Material to material? How about first vs tenth cut for a given wheel?

Not looking for the actual answers, just want to understand that if, cutting material A with wheel X was the same time to cut (normalized for material thickness) as cutting material B with wheel X.

Thank you,
Bill

I would not use the cutoff wheel on aluminum...abrasive wheels are not designed to be used on aluminum. It's pointless, and could get dangerous.

Can't wait to see the final results of your testing though....on ferrous materials

planet6racing said:

Did you measure the time required for each of the cuts for a comparison of wheel to wheel? Material to material? How about first vs tenth cut for a given wheel?

Not looking for the actual answers, just want to understand that if, cutting material A with wheel X was the same time to cut (normalized for material thickness) as cutting material B with wheel X.

Thank you,
Bill

Click to expand...

I was wondering the same thing. I would guess your biggest consumable cost is not the wheels but TIME. I would much rather pay for a more expensive grinding wheel that does not last as long but cuts faster. My time, especially while grinding is worth more that the wheels.

Yes, we are timing the cuts. From start to finish, then averaging the totals. And will certainly factor that in later, as well as price per cut. You're right though...speed is a big factor. Which includes wheel-changing time. I might think a wheel getting 50 cuts before needing changing (say on a 1 day job of cutting over and over job) would still be quicker (most cuts for the day) vs a wheel that gets 25 cuts, even if that wheel is showing slower cut times in our test by a few seconds. One could do the math, which I will eventually, but you see my point.

10-4 on the Aluminum! I did not know that, obviously, and won't mess with. Thanks for possibly saving some stitches or worse