Grinding aluminum without the grit

At the risk of summoning the ire of Dr. Jeffrey Badger, the legendary Grinding Doc, I bring you some handy little insights from our humble little shop’s surface grinding exploits. Today I’m going to focus on two simple and interesting topics: wheel compound and grinding on non-ferrous metals, specifically aluminum.

March 30, 2026By Robert M Layng

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Surface grinding is mostly governed by the laws of wear. As I was taught, the laws of wear govern two interacting surfaces, one being necessarily harder than the other. In the world of surface grinding, the wheel (cutter) is harder than the workpiece, otherwise the workpiece would just invariably consume the wheel. Just as it is with milling, drilling or turning, the cutter must be harder than the material being cut to be effective.

In a sort of subset of these rules, I was also taught that the harder the workpiece material, the softer the compound of wheel should be. For example, if you are grinding on soft 1018 machine steel, you should choose the hardest compound of wheel that you have. Conversely, if you are making sparks on something hard, such as when modifying a tool steel cutter, you’ll want to mount a standard white aluminum oxide wheel. Of course, make sure your wheel passes the ring test, is properly mounted, balanced, and is dressed sharp and clean.

Coolant is a must, be it from a misting nozzle, minimum quantity lubrication or flood coolant. No Iron? No Problem! In my formative years I worked for a tool and die shop that made thermoform molds and the corresponding dies to punch the final product from the stock material.

As I moved up the ranks, I found myself spending a few shifts in the grinding and finishing room, putting the finishing touches on the exact molds I’d made a few days prior. Here’s a twist I faced with two pieces of a mold made of 6061-series aluminum! Hardly magnetic. I needed to find a way to hold the mold on the shop’s magnetic chuck.

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Cutting Tool Engineering

Be sure to catch me The nice thing about this setup, I’ve found, is that you

on CTE’s newest can retain very similar down feeds and cross feeds as podcast, “The Daily you would with the same wheel on steel parts. Grind” where we There is one side effect that I’d like to point out. WD- talk about things just 40, as it is meant to do, leaves a filmy residue on what- like this and so much ever surface it is applied. Make sure you put in some.

Be sure to catch me The nice thing about this setup, I’ve found, is that you on CTE’s newest can retain very similar down feeds and cross feeds as podcast, “The Daily you would with the same wheel on steel parts. Grind” where we There is one side effect that I’d like to point out. WD- talk about things just 40, as it is meant to do, leaves a filmy residue on what- like this and so much ever surface it is applied. Make sure you put in some more, with a new guest good effort to scrub your parts with a mild cleaner after each week. Live, Monday mornings at 8 a.m. Eastern, you’ve taken them off the machine and deburred them. and wherever you get your podcasts on Tuesday It is also a great idea to spend the time to dress mornings, perfect for the commute into the office. your wheel again after you’ve completed your alumi-

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For jaws, I used a series of steel pieces just a little bit thinner than the finish height of the mold halves. The toolmaker I worked for at the time taught me to arrange the two mold halves at around 30, then surround the plates with the steel jaw bars and press them firmly against the sides of the plates before kicking on the magnetic chuck. I chose the most open compound white aluminum oxide wheel I had, mounted it, touched it off and set my depth for the first cut. This is where I introduced another twist.

I didn’t use any of the conventional coolant supply methods on board the machine. Instead, I sprayed a healthy coat of WD-40 on top of the plates before I started the passes, and applied another coat after the wheel completed each path across the parts. The WD-40 acted as a barrier between the aluminum particles that were cut from the plates and the grits of the grinding wheel. It prevented the aluminum from gumming up and lodging inside the voids between the grits, which meant the tiny aluminum chips could fly free of the wheel and the part.

That allowed me to grind aluminum parts with relative ease. The nice thing about this setup, I’ve found, is that you can retain very similar down feeds and cross feeds as you would with the same wheel on steel parts. There is one side effect that I’d like to point out. WD-40, as it is meant to do, leaves a filmy residue on whatever surface it is applied.

Make sure you put in some good effort to scrub your parts with a mild cleaner after you’ve taken them off the machine and deburred them. It is also a great idea to spend the time to dress your wheel again after you’ve completed your aluminum grinding job. If not, the WD-40 can and will sit in the voids and on the exposed grits, which could cause problems down the road. A few passes with your dressing diamond should fix the problem.

The last thing you want is to go and grind some steel parts with an oil-like substance embedded in your wheel. Ihope these tips help anyone faced with the need to grind a surface on an aluminum part. Just remember, your day may be a real grind, but that doesn’t necessarily mean you’ll have a bad day. Thanks for reading.