White Grinding Wheel

I ordered a white grinding wheel from my local engineering supplier and when I went for it he'd come up with a usual grey one (although he called it green!)

Now he says that will do so what if any is the difference of a white wheel?

"green" wheels are "soft" for use on hard materials like carbide and tungsten carbide.. Soft in this case means the "grit" is held in with a soft binder so that it sheds and gives new cutting faces as you work..( otherwise the grit particles get blunt)..

The White wheel is probably ali-oxide.. hard grit , hard binder...

Both will "cut" carbide but the green wheel will require more frequent dressing .

sorry cant help futher...Dave C seems well informed..

Hi Wolfie

What is the code on the wheel?

regards David

The most common abrasive in grinding wheels is alumina (aluminium oxide), and the wheels made of this are most commonly white, sometimes pink, and possibly other colours. This is fine for grinding steel as alumina is harder than steel.

It is not though hard enough for grinding tungsten carbide. The only commonly available materials for grinding this are silicon carbide and diamond. Green grit wheels are silicon carbide in a soft matrix. They do grind tugsten carbide, but slowly and with rapid wheel wear; they are really old hat, and diamond wheels are cheap enough, longer lasting and faster working.

Stick to alumina wheels for HSS and diamond wheels for tungsten carbide. You supplier should be able to guide you as to the best grade, but a middling grade alumina in a vitreous medium should be fine.

I don't know what the grey wheel signifies, you need to get him to be more precise. If it really is grey I doubt it is silicon carbide, but he must be able to tell you precisely what it is - he has no business to be selling grinding wheels if he can't.

David

Edit - DC's post appeared while I was composing this - he has asked the most sensible question of all!

Edited By David Littlewood on 10/08/2012 18:05:44

I think this reference **LINK** is fairly clear - and tells us that grey is commonly used for alumina wheels for fairly rough grinding. Now I come to think of it, my original bench grinder had coarse grey wheel on one end and a fine white one on the other.

David

Hi There

The first thing I did with the grey wheels that came with the grinder was... throw them away.

I expect you could have bought a new grinder with two cheap grey wheels for what they charged you for the single grey wheel.

regards David

Grey wheels are usually carborundum, OK for general rough grinding.

J

Jason,

I think you are cofusing carborundum (silicon carbide) with corundum (aluminium oxide). Grey wheels, AFAIK, are aluminium oxide, not silicon carbide.

David

Now that many of us are making our own cutter grinders pehaps David could persuade one of the grinding suppliers to produce a series in MEW regarding what does what and which types to use.

ray

David asks what is the code on the wheel and I agree but we should also ask, What did you order, was it just the size and the colour White. Did you not quote a specification or at least what you intended to use it for. What do you intend to use it for, high speed steel, tungsten carbide or mild steel?

You ask what is the differnce between a grey and a white wheel. Of the cuff I could not explain, but I do know that wheels intended for sharpening HSS tooling are invariably white, occasionally pink i think.

In my experiance the white wheels I have are much superior for grinding HSS compared to the grey wheels on my general purpose grinder.

Harold

Dacid L

Carborundum wheels here

Jason,

If you expect retailers to always use the right word, you are obviously more of an optimist than I am.

David

I am pleased to see this conversation.

I have given up phoning and emailing suppliers to try to locate a 125mm diameter x 16mm wide x 13mm bore wheel suitable for fine hand grinding HSS lathe tools. Only one supplier could help me but he could only sell me two wheels at about £18 each, which was too much.

I have now put my old grey coarse wheel back on and resolved that one day, probably never, I will make sure that I can buy suitable 'special' wheels at the same time as buying a new bench grinder.

I would be pleased to learn more about these new-fangled (to me) diamond wheels: speeds, temperatures, grit equivalents, good and bad treatment, etc., but I don't know where to find the information. Has there been an MEW article?

Merlin,

Diamond wheels are, in general, totally unsuited to grinding steel of any description; have a look at the link I posted above. You should get a decent white alumina wheel.

David

Hi

Interestingly, well maybe, is some of the grinding wheels listed as 'Green' shown on the site, as linked to by Jason, and being suitable for TCT tools are actually 'Grey' in the illustration. Maybe a illustrator's error or perhaps they are 'Grey' but 'Green' wheels.

As David says and others have concurred with get the code for the wheel and then check for suitable uses.

Cheers

Martin

I like merlin..have struggled to source good wheels ...for work..

three ..go clunk..returned

four ..out off round..2-5 mm...returned

one ..badly miss balanced...even if bore concentric to 0.1mm and "round"..returned...

finally one fit to spin.....thats 1 in 9..

still too course (same grit/binder/ grade but defo not same wheel)

after much dressing (thought I would run out of wheel!) passable results..drills still look like the have chip breakers though!

Best of luck..

Btw our centerless grinder wheels are blue/grey carborundum...

Not much point in saying this, but I am surprised that it is so difficult to buy a wheel for grinding HSS -lathe tools - surely a very common requirement in the ME world?

Perhaps the small 125mm diameter requirement is the problem.

I would have taken Geoge Thomas's advice and bought a white 80 or 100 grit wheel 30 years ago but I couldn't afford it then.

In one of my recent phone calls a supplier told me that I needed green grit for HSS.

Wheel info:

• (A) Brown/Blue Regular aluminium oxide abrasive. Grinding mild steels.
• (WA) White aluminium oxide abrasive for medium to hard steels.
• (PA) Similar to (WA) but with cooler grinding properties, chromium oxide added, to make the abrasive tough & good for precision grinding of alloy tool steels.
• (RA) Ruby this is a very tough form of WA abrasive, which is suitable for holding corners and standard steel applications.
• (GC) Green silicon carbide abrasive for tungsten carbide tooling.
• (SG) Light Blue a Microcrystaline abrasive which means it breaks down in micro parts, it is a high performance abrasive for very cool & fast stock removal of hardened steels e.g. Tool Steels.
• (454A) Blue ceramic abrasive for grinding hard to difficult to grind steels.

• Grit size. Coarser---24-30-36-46-54-60-70-80-100-120-150-180-220---Finer
• Bond hardness Softer---G-H-I-J-K-L-M-N-O-P-Q-R-S-T---Harder
• Bond type. V= Vitrified. B=Resinoid

Paul

A very handy reference ... Thanks Paul

Is this standard across all [reputable] manufacturers ?

MichaelG.

Not sure about all manufacturers but AFAIK most of the major ones.

I normally buy my wheels from Abtec either through their site or on occasion when they have a sale on eBay.

Just bought 2x PA 54 JV wheels from their eBay auction for less than a tenner with shipping.

Regards

Paul