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Thread: Bench grinder and Aluminum?
07-22-2005, 02:51 AM #1
If I recall correctly my Ryobi bench grinder warned me not to grind aluminum. I understand that the wheel might tend to load up, but is there any harm in using it to deburr edges? I think the manual warned that the disk might explode and all manner of mayhem might ensue. Is this just lawyer talk, or is there a real problem here? If it's real, then how should I deburr aluminum. I'm generally talking 6061 rod or plate.
Thanks in advance for the wisdom you share with this hobbyist.
07-22-2005, 02:54 AM #2
I did it without incident on my cheezy 4 year old taiwanese crap bench grinder. The only issue was the wheels loaded up *really* fast, and it took forever to clear all the aluminum off them later. A wheel dresser would've helped...
I don't see how grinding aluminum will cause the wheel to explode.
07-22-2005, 03:04 AM #3
Well, I decided to dig up the manual and I slightly misremembered. It only says, "Warning, never sharpen or grind anything made of aluminum". They just give this dire, but unjustified warning and it is given as a "safety" issue.
Could heavy loading bring the wheel out of balance...or is this just CYAWP BS?
07-22-2005, 03:06 AM #4
Be more professional and use the right tool for the job. If you just want to debur aluminium get a deburring wheel.
07-22-2005, 03:26 AM #5
First off its not practical to grind aluminum with a stone grinding wheel. Since it clogs up so fast you have to constantly dress it to reexpose the cutting surface.
Second grinding wheels are bonded so once the wheel gets loaded if you keep applying pressure the wheel will over heat and will literally come apart!
and third I have heard that if grind aluminum and then iron you can potentially have a fire due to the reaction between them.
07-22-2005, 03:28 AM #6
What happens is the wheel loads up to a point that it wont grind at all.
Then somone will try to grind a piece of steel, and will apply extreme pressure to do so and break the wheel, and that may kill you.
07-22-2005, 03:44 AM #7
If the belt sander isn't precise enough I reach for a single cut file.
07-22-2005, 05:18 AM #8
When you grind aluminum on a standard grinding wheel it will load up quickly. The aluminum is filling in the voids in the wheel and can expand and cause the wheel to explode due to internal stresses caused by the aluminum expanding. Even after dressing the wheel some of the aluminum may still be the pours of the wheel. The next person grinds steel and heats up the aluminum and they have the problem.
For deburring get a 3M or other brand name wheel made for that purpose. They work fine and last along time.
07-22-2005, 06:23 AM #9
There's still some shop where if you're seen grinding anything but steel on a shop bench grinder you stand a good chance of spending some time on the beach in a non-paid status.
Aluminum and non-ferrous alloys are verboten on bench grinders. Grinding anything but steel with my grinders without special permission will fetch you some rough language and maybe a lump or two if you're in range.
If you want to de-burr aluminum use a belt sander. A 1" x 42" belt sander is one of the handiest tools to have in the shop especially for de-burring and touching up details.
Many times I use my pocket knife to deburr aluminum closly followed by a burr-quik (local name for a castering de-burring tool of marvelous convenience and versatility) a file, and the 1" beld sander.
07-22-2005, 07:38 AM #10
Lesse... Portland, to here... couple of hundred miles, at least... OK.... so the wheel fragments shouldn't hit me when it does blow... ummmm.... OK...
What'cha talkn' 'bout? You can grind that thar 'lumnuuum all day on that thar thang! Sheeeure!
(runs and hides)
07-22-2005, 08:44 AM #11
As I misremember it, micro-fine aluminum powder is used in military flares and in some explosives.
I DO remember that powdered aluminum is a dangerous material when mixed with powdered iron. I believe the mixture is called THERMITE!!!
Do you really want powdered aluminum anywhere around your shop where you might have added, or will add, grindings of iron-bearing products?
DON'T DO IT! Please?
My 2¢ worth.
07-22-2005, 10:07 AM #12NiftyNev Guest
07-22-2005, 11:03 AM #13
GREAT CEASER'S GHOST!!!! Does this mean that the powdery dust at the base of my 4 X 36 belt sander, where I grind and deburr all kinds of materials including steel and aluminum, is a major hazard?
Mebbe it WAS worth checking this forum this morning!!!
07-22-2005, 11:21 AM #14
I think the "government" thing is a possible hoax.......or typical "theorizing" by people who really have no experience and no real knowlege. The latter is more likely, the writer was not there, and did not see whatever happened, if anything.
That said, I have "ground" aluminum and followed up with steel, on the belt sander, and seen a few bright white flashes. So I suppose its possible.
But the details in that "government" report are highly suspect....there may have been a flash, etc, but I strongly doubt it was just like that.
Giving the diameter of teh "fireball", etc, etc. Oh, pu-leEEEse. That guy wasn't there, and I'll bet the "victim" has no clue.... in that kind of situation you generally don't, it comes down to "what the %%%%?".
I know folks who have TRIED to get a thermite reaction to "go". It isn't easy, and I doubt 12 rivet heads will do the job. Maybe if they were magnesium....
That goes double because the "mixing" won't be very good between the aluminum and steel dust. The real thermite is well mixed, in the right proportions. Random mixing from grinding will be uneven, with layers formed, etc.
Finally, the steel isn't ALL or even MOSTLY turned to ferrous oxide. There are sparks, yeah, but most of the grinding dust I get is still "steely-looking". So you are down to "lighting" the aluminum. If actual thermite reactions had occurred, it would have left globules of steel.
Possibly it lit some aluminum, just by hot sparks, but even that isn't easy. I gotta wonder if that report is even partly accurate.
Then also, the "fireball" seems odd also. Thermite is spectacular, but it does not explode. If it threw that much stuff around it wouldn't be useful, it would blow itself out of the pot.
Aluminum dust also doesn't just jump up and explode, even if provoked. One is left to wonder if the ingredients in teh occurrence were all known and listed.... like what other dusts were around?
Was the steel that was being ground oily? An oil mist explosion would be possible if so.
Grinding aluminum on a wheel is just not done....loads up as umpty-bump people have said above. I doubt there would be much dust, looks like it mostly sticks to the wheel, depending on alloy. Yet another strike against the "report".
[ 07-22-2005, 04:58 PM: Message edited by: J Tiers ]
07-22-2005, 11:57 AM #15
Quote 1: In powder form, aluminum and its alloys are combustible in air and present a potential explosion hazard.
Quote 2: Thermite Reactions
Aluminum readily extracts oxygen from other metal oxides to form aluminum oxide with the simultaneous release of large amounts of heat (enough heat to melt the products of the reaction). For example, the reaction of aluminum with ferric oxide to produce liquid aluminum oxide and liquid iron produces temperatures approaching 3000°C (5400°F). This reaction, referred to as the "thermite reaction," has been used to weld large masses of iron and steel; when enclosed in a metal cylinder and ignited by a ribbon of magnesium has been used in incendiary bombs; and, with ammonium perchlorate added as an oxidizer, has provided the thrust for the space shuttle booster rockets.
Quote 3: Dust Explosions
A dust explosion is a complex phenomenon involving simultaneous momentum, energy, and mass transport in a reactive multi-phase system.13 Aluminum particles, when in dust, powder, or flake forms from operations such as manufacturing powder, grinding, finishing, and processing, may be suspended as a dust cloud in air and consequently may ignite and cause serious damage. If the dust cloud is unconfined, the effect is simply one of flash fire. If, however, the ignited dust cloud is at least partially confined, the heat of combustion may result in rapidly increasing pressure and produce explosion effects such as rupturing of the confining structure. Aluminum dust is not always easily ignitable, and, therefore, the hazard of dust explosions is often ignored.
'Nuff said.... 'cept... better to be safe than dead.
07-22-2005, 12:50 PM #16
Use the right tool for the right job and for deburring aluminum that is a Scotch Brite 7S fine wheel. If the burrs are heavy then use a belt sander first and then the Scotch Brite wheel. If you are machining aluminum and generate heavy burrs use a sharp cutter. [img]smile.gif[/img]
Professional Bench Top Work Positioners
07-22-2005, 03:24 PM #17
Well thanks to one and all for the lively and informative discussion. I will take all to heart, and as always I appreciate the information and opinions.
Should I assume the general solutions also apply to other non-ferrous metals such as stainless steel?
-Art K (who has and will only grind steel on his bench grinder )
07-22-2005, 03:33 PM #18
I believe stainless is ok to grind. In fact I believe stainless counts as ferrous, seeing as it does, after all, contain Iron.
Sorry to hijack the thread, but I was wondering what the consensus is on using cutoff wheels on aluminum. The folks I work with do it all the time, but having seen grinding wheels loaded with aluminum, it makes me rather uneasy to be using any sort of grinding tool on aluminum. Of course having worked with people who do it all the time for several years and having seen no mishaps in that time, they've somewhat lowered my resistance to this practice. So I have, on occasion, been know to use a cutoff wheel on aluminum myself in recent months. Any thoughts on the practice?
07-22-2005, 05:26 PM #19I was wondering what the consensus is on using cutoff wheels on aluminum.
Professional Bench Top Work Positioners
07-23-2005, 07:25 AM #20
aluminum forms a chemical bond with a/o wheels,
then sticks like glue. if you must grind aluminum
...a silicon carbide or "masonry" (also known
as "masonary") wheel is the ticket for the job.
light grinding on a bench wheel or angle grinder's
not 'gonna hurt anyone...or cause any thermite
reactions...! i've seen retards load a wheel
plenty of times, but the only fires i've seen
were from hot sparks ...from steel.