"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..

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

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

Jason,

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

David

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

Jason,

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

David

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

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…

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

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

.

So lets look at this logically.

if you are not looking at using HSS which you can regrind you are looking at inserted tips.

Taking the average tip to be £4.00 and you get 3 cutting edges you are getting about 14 cutting edges for £18.00.

I'm damn sure you can regrind a HSS tool more than 14 times before the wheel is worn out. Chances are you will get 500 to 700 uses out of a wheel so that equates at the lowest figure to three and a half pence per use , stretching to two and a half pence.

If you are that tight you could always save the dust and re-glue it up into a new wheel.

John S.

Hi David L and Jason, "Carborundum" is actually a trademark for silicon carbide abrasive. I can remember when I first started working for a living in a Blacksmith shop, where there was a tapered square stick about 12" long with CARBORUNDUM cast into one side. It was used to sharpen knives and the like by hand.

Discounting diamond and any other uncommen grinding wheels, there are two types of abrasive used, which are Aluminium Oxide and Silicon Carbide, but there are a number of different bonding mediums for holding the abrasive. I guess that manufacturers can make thier wheels any coluor they choose, however most AO wheels I've seen are grey, while I can only remember seeing green SC wheels.

There is a standard classification used for grinding wheels and the codes are what you need to get the right one and should be sought. Below is a scan of the codes used on well represented grinding wheels.

Regards Nick.

Edited By Nicholas Farr on 11/08/2012 18:01:40