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StephenK
02-25-2008, 08:40 PM
I have been asked if it is possible to surface grind aluminum.

The reason for this is that a person that I have done work for is in the process of setting up a small injection molding machine which takes a mold size of 2.5 x 3.0 x 0.75. There are two blocks per mold and the mating surface should be such that there is no flashing of the polyethylene material injected.

I have ground for him two steel blocks with a fine finish, practically magnetic however it would be easier to machine the needed cavity if the mold was made from aluminum.

When I was still in Medical Device Development we did have some aluminum plates ground for us. This goes back about thirty years ago. Watched the person doing the grinding but didn't get any details.

I'm open for suggestions.

Stephen K.

Ten years retired and still can't catch up with my projects.

Fasttrack
02-25-2008, 08:46 PM
Grinding aluminum is not commonly done because its pretty rare that you find an application where you can't machine it due to hardness issues. Its also fairly rare to need the precision from grinding on aluminum pieces but formula engines do need that precision.


I bet if you do a search you will find good information on the process but from what i know, they have special surface grinders that run a silicon carbide wheel and special coolant to surface grind cylinder heads and blocks to within .00025" :eek:

StephenK
02-25-2008, 09:03 PM
Fasttrack:
The information that you mentioned was what I was able to find. The wheel that is used is a silicon carbide but it did not mention the coolant.

I use one of the Norton silicon carbide grinding wheels to surface the magnetic chuck on my grinder. It does a great job if your careful. I will be looking into adding coolant. My grinder is a 6 x 12 bench model which has served me well to date.

SK

mochinist
02-25-2008, 09:07 PM
I do it on my big mattision occasionally and the grind house where I send jobs that are to big or just dont have the time to do, grinds aluminum all the time. I was in there last week and they were grinding some big fixture plates that had a couple thousand drilled and tapped holes in them, the material was cast aluminum(mic 6) and it comes blanchard ground from the supplier, but all the holes being put in make the secondary grind necessary.

When I do it I dont put on a special wheel or anything, but I do have kind of a general purpose grinding wheel. Just use lots of flood coolant and make sure the part is blocked in really well, since aluiminum magnets havent been invented yet.

Fasttrack
02-25-2008, 09:16 PM
Yeah i think the most important part is a coolant that is appropriate for aluminum. Most water-soluble synthetics now work good on aluminum. With lots of coolant the aluminum won't load the wheel... or thats the theory anyhow.

agrip
02-25-2008, 09:46 PM
In days before synthetics, water borne coolants on a grinding wheel would react with aluminum making one mell of a hess.

Petroleum was used to grind aluminum and did very well, as long as the swarf came out cool. One way to keep the swarf cool(er) was to use the much "sharper" silicon carbide grain.

I have not ground aluminum in a long time, but do know that synthetics have opened up the world of surface chemistry, I defer to fasttrack's suggeston of synthetics likely doing well with grinding aluminum.

Of course, asking the synthetic coolant guys "how about aluminum?" can't hurt, except to wear your ears out.

One word from the annals of history {B-)
Never Never EVER buy coolant from a place that the same guy also sells floor wax.

Ag

wierdscience
02-25-2008, 09:59 PM
I've doen it a few times,nothing special,just a good AOX wheel with a fresh face and lots of coolant.We use soluable oil on everything mixed 40:1 with water.The wheel stays sharp a long time since the aluminum is so soft.

Fixturing can be a problem,a quick solution is a ground piece of steel super glued to the back of the workpiece.

chrsbrbnk
02-25-2008, 11:23 PM
We do it all the time best is a coarse open sharp wheel usally a good friable white wheel. Lots of coolant watch for wheel loading. that small a part I would lean towards a vice We often just block in with steel but that is more size dependent double sided tape is good for a thrill too

Fasttrack
02-26-2008, 12:01 AM
Yeah - definitely check for wheel loading after every pass or so until you get a feel for it. Its easy to blow one of those wheels up if it gets loaded with Al.

Evan
02-26-2008, 12:10 AM
Aluminum is surface gound as a matter of course on a production basis by all the aluminum producers. Aluminum tooling plate in various alloys is a surface ground product and is a standard stock item. 6061 tooling plate is most common followed by 7075.

JoeFin
02-26-2008, 06:56 AM
Iíve done Aluminum engine heads in my grinder

DOHC engines have cam journals that are parallel to the head surface, makes it too easy to build up an adaptor plate out of steel for grinding. I used a synthetic oil (rustlik) and a White wheel. Didnít have any problems what so ever, sure missed the sparks however.