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What type of wheel is best suited for grinding HSS M2?

A.Delaney

Aluminum
Joined
Nov 23, 2015
After many hours of researching. I had reached the conclusion that I needed a CBN wheel for grinding HSS in my surface grinder. I contacted a company called Eagle Superabrasives. They specialize in CBN and Diamond wheels. They agreed a CBN wheel is what I need for grinding HSS however felt my machine was lacking with only a 1hp spindle. I would not see much benefit for the 5 times in price over an AO or Ceramic wheel. Here are my questions. Has anybody ground HSS using a CBN wheel? How does it perform compared to an AO or Ceramic? Do you think a 1hp machine would be under powered for removing .005" total material per side? I have 48 parts to grind. Even if I could only take .001" per pass I would be happy. Im taking .0005" per pass right now and I have to dress the wheel every couple passes. I want to be able to grind at least 2 parts at a time and do a couple sets before dressing again. Is there another type of wheel that works good for HSS that you have used other than a CBN?

Here is a few wheels I have tried.

Radiac 8BP46 G800 VOS
Radiac 8BP46 J8 V8
Radiac RA46 H8 V8
Radiac 8BP46 H800 VOS
Norton 5SG46-JVS

I use Q Cut 225C cutting and grinding coolant with water.
I have tried slowly dressing the wheel with my diamond and also dressing it more aggressively. In addition to this thread I have emailed Norton about my issue and am anxiously waiting to see what they have to offer.

Thank you for any help.

Aaron
 
How big are these parts? I have the same or less HP in my old Boyar-Schultz and .0005" per pass would be right for me. Everybody recommends those expensive Norton 5SG wheels, but I wasn't thrilled with my 60 grit, though maybe it was because I didn't have the special dressing diamond they recommend, just my regular one. I dress aggressively and usually do OK with a plain old white AO wheel. A slow smooth dress is a recipe for trouble. Now, if your parts are larger than some 3/8" lathe tool bits, optimizing the wheel may make sense.
 
Figure out what's the smallest wheel diameter that could be effective on your grinder, then talk to the CBN wheel vendor to see if that would help the low HP situation. It would lower the surface speed, which would hurt MMR, but decrease the torque acting against the low HP motor and reduce the arc of engagement, both (potentially) helping your grinder to function, even if slower that ideal.

With the low erosion of a CBN wheel, even at smaller diameter you should be able to grind more pieces and maintain accuracy longer.
 
How big are these parts? I have the same or less HP in my old Boyar-Schultz and .0005" per pass would be right for me. Everybody recommends those expensive Norton 5SG wheels, but I wasn't thrilled with my 60 grit, though maybe it was because I didn't have the special dressing diamond they recommend, just my regular one. I dress aggressively and usually do OK with a plain old white AO wheel. A slow smooth dress is a recipe for trouble. Now, if your parts are larger than some 3/8" lathe tool bits, optimizing the wheel may make sense.

My parts are 2”x5”x .551” thickness. Not solid though. There is 2 holes and then a cutout on one end.
 
Figure out what's the smallest wheel diameter that could be effective on your grinder, then talk to the CBN wheel vendor to see if that would help the low HP situation. It would lower the surface speed, which would hurt MMR, but decrease the torque acting against the low HP motor and reduce the arc of engagement, both (potentially) helping your grinder to function, even if slower that ideal.

With the low erosion of a CBN wheel, even at smaller diameter you should be able to grind more pieces and maintain accuracy longer.

I will contact him tomorrow about this. I have a wheel in the grinder now that’s about 5”. It seems to bog less than the 7” wheel.
 
Wheels you mentioned should grind OK for that material IMHO..
Are you incrementing across .. hold the down feed set in one position and steeping across with the cross feed? This is the most normal grinding method.

Coming down feed incrementing is not common on a light grinder. That is down feeding with cross set and left in one place.Can be a good way to grind with some jobs to come to + .002 or so then increment across for tickle finish.

I don’t think that light 1Hp and belt drive would be good for CBN wheels but the wheel vendor may have other customers who may give insight to the wheel he recommends.
*I have use 3/4 Hp direct drive grinders on just about everything and that has been plenty of power.
Need to be sure spindle drive belts are tight.. I don’t remember an adjustment on that machine so just need to replace belts if they don’t hold..*and drive pulleys have to be clean and dry..

I used a belts drive Micromaster(belts drive) on super hard broach cpm stock and it would hardly grind that material.think they were 24" long and the smallest cut would try to stall the machine spindle.

Are the parts sold in structure to the wheel pressure and not bending away with the grind? That can cause a wheel to not penetrate the stock. Perhaps look at some you tubes to see grinding action on mild stock and note if your machine grinds as well.
Perhaps grind a sample of cold roll to see it grinds as well as you see in the you-tubes.
Grinding wet an asset because hard work likes to grow up into the wheel adding more wheel pressure need. Yes you said you are wet grinding.

Hard work stacked close together will not let the RPMs come back to speed..so with a grinder losing speed a space between and some over travel at the ends of travel can help.

Yes back in the day I would full fill a chick with a row of hard parts on a 3/4 Hp Reid direct drive ..going across a little slower with long travel and had no problem. At that same shop I had a 3Hp pope on a Reid 6-18 used for carbide specials and having electro chemical DC for carbide grinding specials.

You may have to send a batch to a local grinding shop so to see if they have the same problem..

You don't need any fancy diamond but one you can turn to get a new facet facing the wheel..A diamond that stands straight vertical can not be turned to a new facet..so the diamond needs to be at angle. A round nose diamond will/can dull your wheel.
 
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In 35 years of grinding with 'super abrasives' with 1 h.p. grinders I have never needed more power. Heavier cuts make too much heat so 1/2 thou max depth of cut.

I do like 5" wheels IF THE WORK WILL CLEAR THE SPINDLE HOUSING, which it will not on a Mitsui, so 6" wheels are needed.

Wheels will last so much longer than AO or SG they end up being much more economical to use, plus with proper grinding techniques rarely need dressing.

Edit: forgot to mention, For D-2, M-2, M-4, T-15 and so on, once you use cbn there is no reason to use AO wheels again.
 
When you get it figured out..You might add an off-chuck diamond..set to perhaps + .001, .005, .010 or even dead zero size.

You then don't have to raise or lower the head to dress just go off at the far end and skim the wheel. With the hand dial-set telling where the wheel is..


Yes an overhead dresser can be handy but many machine don't have that.
 
Here is what they look like. I have a Harig Super 612 that I have ground a couple of these on in the past. Now that I think about it. I don't remember the wheel bogging down. Im going to try that again. If the wheel doesn't bog down then it must be something with the other grinder. Either the machine or the coolant.




chopper blades.JPG
 
looks like a sold part and so should grind well..future parts should have minimum stock for removal. Parts would grind well on my B&S #2 or any of my grinders with the wheels you show..

machine, coolant, motor running with specified Hp due to wiring or the drive belts slipping IMHO..

looks like a good finish so likely rule out spindle problem..
 
Well I tried grinding without coolant. It actually seems a little better. Also my wheel is wore down to about 5" diameter. Max cut depth is still .0005" per pass though. Maybe that all I'm going to get from this. The parts didn't get hot at all.
 








 
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