Preventing aluminum on a bench grinder

I have been tasked with setting up some shop guidelines and training for the engineering lab where I work. Unfortunately I have one engineer who insists on grinding aluminum on our bench grinder, and has done so on several occasions. When I was taught this was up there with leaving the key in the chuck, a big no-no for standard black bench grinder wheels for various safety reasons. I keep getting "I've done this dozens of times and not had a problem yet", and our mutual manager doesn't really care.

1) I am assuming this really is a safety issue. Am I correct in this?
2) Are there any accident reports or OSHA rules I can point to. If I can provide written evidence opposed to "Those old grumpy guys said so" I think our manager will agree. I've found surprisingly little in a search, so perhaps I'm using the wrong search terms?
3) I am going to decline to set up the safety guidelines if they won't be reasonably followed/enforced, but I want to try education before giving up, and being engineers we tend to respond well to "here's why" explanations we understand.

We do have a maintenance group in the plant with machining experience. Every time I'm in their area the Bridgeport has a different 1/2" carbide end mill with chipped teeth in a 3 jaw Jacob's chuck. Their mill rumbles like a freight train, and that's after they "rebuilt" it. Point being, I don't want to have skilled machinists in the building to have train these guys or set guidelines.
I advised having our new techs go through basic machining classes at the local tech/trade school, but that was turned down, and don't think I will be able to change that decision.

jccaclimber said:

We do have a maintenance group in the plant with machining experience. Every time I'm in their area the Bridgeport has a different 1/2" carbide end mill with chipped teeth in a 3 jaw Jacob's chuck. Their mill rumbles like a freight train, and that's after they "rebuilt" it.

Click to expand...

Hate to say it, but I really dont think they have experience.

Not sure how you see grinding aluminum as being a safety issue. What exactly do you see happening as a consequence? I'm not saying that it's a great idea, it tends to load the hell out of the wheel causing the need for heavier and more frequent dressing, but I can't see anybody being killed from it! Maybe I'm missing something.
End mills in a drill chuck is just stupid and lazy. That goes for HSS and carbide, but I guess if I had to do it in a pinch, I certainly wouldn't use carbide. I can see you having a safety issue with that one, to me it's really just more stupid and wasteful!

Mebfab said:

Hate to say it, but I really dont think they have experience.

Click to expand...

No, they don't, but it's been the same guys there for at least 5 years so I don't see it changing. Fortunately this is a different group of guys than the ones I need to teach.

Derek Smalls said:

Not sure how you see grinding aluminum as being a safety issue. What exactly do you see happening as a consequence? I'm not saying that it's a great idea, it tends to load the hell out of the wheel causing the need for heavier and more frequent dressing, but I can't see anybody being killed from it! Maybe I'm missing something.
End mills in a drill chuck is just stupid and lazy. That goes for HSS and carbide, but I guess if I had to do it in a pinch, I certainly wouldn't use carbide. I can see you having a safety issue with that one, to me it's really just more stupid and wasteful!

Click to expand...

EDIT: See my question and the response from Norton in post #16 here.
The explanation given to me is that aluminum gets mashed down into the wheel and then later expands under the heat of someone grinding steel. This expansion causes the wheel to crack and come apart. I've been told this several times, including by one person who unfortunately got to watch a wheel explode about 10 feet from him in a maintenance shop on a Navy ship. He described it looking like an IED went off in the shop, I'm not sure what happened to the guy operating the grinder. It seems reasonable, but I'm starting to question it as I haven't found much in writing.

jccaclimber said:

I have been tasked with setting up some shop guidelines and training for the engineering lab where I work. Unfortunately I have one engineer who insists on grinding aluminum on our bench grinder, and has done so on several occasions. When I was taught this was up there with leaving the key in the chuck, a big no-no for standard black bench grinder wheels for various safety reasons. I keep getting "I've done this dozens of times and not had a problem yet", and our mutual manager doesn't really care.

1) I am assuming this really is a safety issue. Am I correct in this?
2) Are there any accident reports or OSHA rules I can point to. If I can provide written evidence opposed to "Those old grumpy guys said so" I think our manager will agree. I've found surprisingly little in a search, so perhaps I'm using the wrong search terms?
3) I am going to decline to set up the safety guidelines if they won't be reasonably followed/enforced, but I want to try education before giving up, and being engineers we tend to respond well to "here's why" explanations we understand.

We do have a maintenance group in the plant with machining experience. Every time I'm in their area the Bridgeport has a different 1/2" carbide end mill with chipped teeth in a 3 jaw Jacob's chuck. Their mill rumbles like a freight train, and that's after they "rebuilt" it. Point being, I don't want to have skilled machinists in the building to have train these guys or set guidelines.
I advised having our new techs go through basic machining classes at the local tech/trade school, but that was turned down, and don't think I will be able to change that decision.

Click to expand...

Don't you have a belt sander? Why not? Grinding aluminum on a bench grinder is pretty stupid, does this moron like the chain saw like finish he gets? I was taught that aluminum forced into the surface of the wheel will cause it to crack. I have not seen it happen myself. Your manager is an idiot as well.

Really do not need an osha regulation.

Seek out standard shop practice documents or for anil management who may not care or know but will read...Get documentation from wheel manufacturer that includes MSDS and operating instructions for said wheel.

Manufacturers of them have likely been sued enough to have their legal department create or approve of operator instructions.

Send to manager via email and copy yourself.

Take that to management and gently advise that the email is discoverable if anyone does something stupid and gets hurt and it is not following manufacturer guidelines.

Then suggest a safety training session where copy is printed and given out.




Sent from my SAMSUNG-SGH-I337Z using Tapatalk

They had a 6 inch wheel let go a few years ago at a friend's service station. It left a small hole in the overhead plasterboard but fortunately didn't hurt anyone. They used to grind everything on the wheel and it often was loaded with non-ferrous crap.

My suggestion: Move the grinder to someplace only accessible to the pros and get a 1 x 30 belt sander for the enginerds. The "engineering shop" at many places I've worked has often been nicknamed the "hack n chop shop".

By the way, the overhead in a service bay is high enough to clear a pickup truck on a lift at full height and is double layer to meet fire codes so that ought to give a hint of how much energy that chunk of grinding wheel had to punch a clean slot through both layers.

If you poke around osha website you can find accident statistics involving grinders. They also include side grinders and machine grinders such as surface and OD, not just bench. But it is an abattoir of maiming and death. Show that to the boss.

As for the wheel exploding, call Norton. Ask them.

moonlight machine said:

Don't you have a belt sander? Why not? Grinding aluminum on a bench grinder is pretty stupid, does this moron like the chain saw like finish he gets? I was taught that aluminum forced into the surface of the wheel will cause it to crack. I have not seen it happen myself. Your manager is an idiot as well.

Click to expand...

All of our products are steel (powder metal or stamped), and fixtures until recently were shipped out, and tend to be steel as well. As a result there was no aluminum around to do stupid things with (or gain any experience). It does seem pretty bloody obvious to me, but apparently it's an issue. Ironically this same guy is actually really good at welding/bodywork and machining on an industrial scale (we make several million assemblies a year). Obviously there are some holes in his understanding elsewhere.

Finding space for a belt sander will be difficult (the drill press is already about on top of the bench grinder pedestal), but I may have another option. The second side of the grinder has some sort of nylon wire brush we don't use much (not sure why he didn't deburr on this). I was going to replace it with a green wheel to grind tools on (I figure if the guys have to re-grind their own tools they will learn to care for them), but I could try to put a flap disk wheel there instead. I am a bit concerned about someone driving too hard and pulling a part under the guard with a flap disk, but I've only used them on hand held grinders so maybe I'me over concerned?

Oh for gosh sake, buy a $40, HF belt sander and put it next to the grinder. Put a sign above it that says "Aluminum and Wood".

If he still uses the grinder for aluminum, make him dress the wheel every time you find it gummed up with it.

Belt sander: $40
Sign: $15
Your peace of mind: Priceless

Me thinks there is the other danger of grinding alum., not the wheel hazard,
but of intermingling of steel dust and alum dust.

I thought it was fire hazard mixing iron and Al on the same pile of grinder dust. OSHA seems to agree. Make sure you have the special metal fire type extinguisher near the grinder. I think the thought is grinding Al is fine but sparks from grinding iron can ignite the pile of Al dust. I remember a paint factory near me would blow up every few years from grinding Al or titanium into super fine dust for paint additive.
Bill D.

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=27413

As with mules, at first you have to get their attention with a 4 x 4. THEN, patiently explain why etc.

I hate to say it but those shitty little sanders are VERY handy to have around. And on the rare occasion they die,
just toss it in the trash and go get another one.. Easy to move around, easy to store, belt change in about 6 seconds
if you throw the guards away... I've got one on a pedestal
and one that is portable, I just use it where I need it and when I need it, and when not in use it
fits nicely under a bench or in a cabinet, even fits behind the seat of my truck if I need to take it home.

EPAIII said:

Oh for gosh sake, buy a $40, HF belt sander and put it next to the grinder. Put a sign above it that says "Aluminum and Wood".

If he still uses the grinder for aluminum, make him dress the wheel every time you find it gummed up with it.

Belt sander: $40
Sign: $15
Your peace of mind: Priceless

Click to expand...

I'm sure that if you take a bench grinder and jam the wheel up with aluminum so good that the face is a smooth shiny silver surface, and then continue to jam ferrous or non ferrous material into this non cutting rotating mass to the point that things are glowing red, getting all sorts of weird, and screaming that somethings wrong, that you certainly could get the wheel to blow up. I don't worry about things like this, because someone who would do something so stupid, is bound to hurt themselves somehow, no matter what they do. It's a wonder they even make it to work in the morning. I have ground aluminum many times, on bench grinders, disk grinders, surface, ID, and OD grinders. It is not ideal. I have never had a wheel explode, then again, I'm not a moron! I understand the principles involved, if a wheel is not cutting freely, for what ever reason, it needs to be dressed.
If mixing aluminum and steel and other dust is such a concern, then I guess I need to go buy about a dozen belt sanders so I can dedicate one to each material I encounter.
As far as you "safety patrol" folks who spend your days fretting over hurting yourself or being sued rather than being productive, STOP! Please, before you have completely ruined our country.
The bottom line is this, If you have idiots working for you who need a nanny to make sure they don't hurt themselves, get rid of them, OR, put them in roles that suite there abilities. They are a liability, no matter what safety guards or protocols you have in place, they will cost you money in the long run. Someone who would force work into a clearly loaded wheel to the point that the wheel explodes, should not be in a position to do so.

I wrote to Norton this afternoon. Below is my question as well as the reply (posted with their permission). It sounds like as long as the wheel is dressed and not used when loaded up (a separate common sense issue), there is not the safety hazard I envisioned. So, is it annoying, yes. Are there better tools for the material, yes. Is the wheel going to blow up in my face later, probably not. If he wants to make it look like he dragged the parts behind his car instead of using a faster and more appropriate tool, I'll offer my suggestions but he can carry on doing so as long as he dresses the wheel after.

Thank you to everyone for your suggestions, especially the obvious in hindsight "Ask Norton". Unfortunately we have no dust collection on this machine despite having vacuum ports on the back of the shields. Fortunately this means the floor is swept frequently, so there is no significant buildup of mixed metal dust. I do periodically check the inside of the grinder shields for slag buildup and it has not been an issue so far.



"
The engineering lab where I work has a pedestal grinder with a black general purpose grinding wheel on it. I have not pulled the guards, but assume it is Norton as the other grinding wheels in our building are. I have a co-worker that insists on grinding aluminum on this wheel, and is of course gumming up the wheel. I have two questions:

1) I have been taught that this is a safety hazard as using aluminum in a wheel for ferrous materials may result in cracking and subsequent explosion of the wheel. Is this the case? If so, or if there are other safety hazards, can you point me to any written guidelines or warnings that I can reference?

2) In addition to the "I've done this for years and never blown up a wheel" response the employee has suggested he simply dress the wheel until majority of the aluminum is removed off the wheel each time he uses it for aluminum. Is this an acceptable solution, or are there still specific safety reasons not to do this?
"

Here is the reply which I am posting with their permission:

"
This is a common misconception spread by over-cautious academics.

It is not at all unsafe to grind aluminum in and of itself.

Grinding wheels dull and/or load up with material between the grains regularly, and dressing is a required step when they do.

Bench/Pedestal grinders are often used by laymen who are not familiar with the process of dressing a wheel.

For that reason, some collegians have published that it's unsafe to grind soft metals like aluminum, because they load wheels quickly and an untrained user might simply bear down harder on a wheel that is no longer cutting because it is loaded.

A loaded wheel that has stopped cutting is just rubbing and creating heat. In theory, if a wheel were abused like that long enough the heat could cause the loaded aluminum to expand, crack the wheel, and centrifugal force would do the rest.

Any machine is dangerous when abused.

As long as the user properly dresses the loaded grains off the wheel on a regular basis, he/she could grind Aluminum all day long with no safety concerns.

There are many different types of dressing tools. Here is a dressing stick that I would recommend:

61463610354 - 1 x 1 x 6 37C24-TVK
"

Go to horrible frieght buy a fake monitor camera bolt it in a place where it can be seen and pointed at the grinder used most. put up a sign "No Aluminum". Have a shop meeting orate a threat of termination directly from management with a dead serious scowl. Same goes for endmills in a drill chuck.
Normally I handle this on a shop level but the threat from above works wonders especially on the newbies.
Nuff said,

Go old school - a large steel toe capped boot up the offenders ass.

Time proven.

scojen said:

Go to horrible frieght buy a fake monitor camera bolt it in a place where it can be seen and pointed at the grinder used most. put up a sign "No Aluminum". Have a shop meeting orate a threat of termination directly from management with a dead serious scowl. Same goes for endmills in a drill chuck.
Normally I handle this on a shop level but the threat from above works wonders especially on the newbies.
Nuff said,

Click to expand...

I like all of your thinking here, but there are two main issues:
1) There is no threat of termination. I could make one, but I have neither the authority nor the management backing for this to work. We aren't talking a problem with Joe P Newbie, we are talking a problem with Richard P Tenured. No real tenure, but nobody where I work is going to fire an otherwise skilled employee for this. Might ban him from using the machine, but that's even a stretch.
2) The end mill in the chuck continues to amaze me. Then again 1) The maintenance supervisor either doesn't know better, or doesn't care enough to do anything about it. I've offered to show his guys how to rebuild their machine a bit better and do some training, he more or less declined in a polite way. That is not my department, so I have settled for teaching the guys in my area better where I do have the backing to enforce that.



I will be posting a "no aluminum" sign, and perhaps discuss any potential exceptions with the entire group. I don't need a camera, nor would one be acceptable there, this (particular) problem isn't one of people doing something in the dark, we know exactly who did what, and he openly mentioned it when I asked.

The person who did this said (and I believe him) that based on years of doing this previously he was not aware of the hazard, but agreed that there are better ways to go about removing material from aluminum parts in the future. I think that closes the issue for me. Quite frankly I am very surprised at the Norton reply saying it wasn't really an issue if dressed after, but they are the experts.

jccaclimber said:

I like all of your thinking here, but there are two main issues:
1) There is no threat of termination. I could make one, but I have neither the authority nor the management backing for this to work. We aren't talking a problem with Joe P Newbie, we are talking a problem with Richard P Tenured. No real tenure, but nobody where I work is going to fire an otherwise skilled employee for this. Might ban him from using the machine, but that's even a stretch.
2) The end mill in the chuck continues to amaze me. Then again 1) The maintenance supervisor either doesn't know better, or doesn't care enough to do anything about it. I've offered to show his guys how to rebuild their machine a bit better and do some training, he more or less declined in a polite way. That is not my department, so I have settled for teaching the guys in my area better where I do have the backing to enforce that.



I will be posting a "no aluminum" sign, and perhaps discuss any potential exceptions with the entire group. I don't need a camera, nor would one be acceptable there, this (particular) problem isn't one of people doing something in the dark, we know exactly who did what, and he openly mentioned it when I asked.

The person who did this said (and I believe him) that based on years of doing this previously he was not aware of the hazard, but agreed that there are better ways to go about removing material from aluminum parts in the future. I think that closes the issue for me. Quite frankly I am very surprised at the Norton reply saying it wasn't really an issue if dressed after, but they are the experts.

Click to expand...

This surprises me to that Norton would say this just for a liability standpoint. Not that I think it is a issue though.

Here is a good one for you though. I use a lot of abrasive belts and one band I use always has directional arrows going in one direction on the back of the belt. I could not figure out what difference it would make what direction the belt is rotating when installed. So one day I asked an application's guy for said belt company at a trade show and his response was it was there in case the was an accident involving one of their belts they could take the stand that the belt was on backwards and was improperly installed. I stood there shaking my head after that. LOL