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Cylindrical grinding aluminum

ZEPMaine

Plastic
Joined
Dec 7, 2021
I've been asked at work the feasibility of cnc cylindrical grinding some aluminum parts. Material is either 6061 or 7075 likely T6 temper (I was not given more details than that). The parts are about 113" long and the OD is a little over 5". The entire OD needs to be ground to 5.XXX" +/- .001". To make matters more difficult the wall thickness is in the ballpark of .25". Is there anyone here that dare touch this job with a 10' pole and if so how would you go about it?

I'm fairly fresh to the world of grinding and any input or experience you can share with grinding aluminum is greatly appreciated even if it doesn't quite relate to my question. I'm interested to learn whatever I can.

I have access to machines that run 20" and 30" OD wheels, are just barely long enough to support the part on centers, and I have steady rests I can set up for additional support.

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Yes, you can (in theory) grind Al this way, but it'll take some experimentation to find the right parameters and coolant mix. Ideally you'd mount a new wheel more suitable for Al than what you have now, but it's likely quite expensive at that size, so running sub-optimal and slower may just be the better route.

You'll want some test lengths of tubing, maybe look at partial fills with sand or similar to aid in damping, and end caps with center holes to suit. If surface finish matters you might need to make coolant-fed pads for the rests, or plan on a post-grind buffing using a belt sander or similar (like they polish crank journals with).

If trying to sand by hand with sheets use a "wrap stick" for the paper, NEVER actually hold the paper in hand at the machine!!
 
Why use grinding?
We turn 2500mm long,120mm diameter, 8mm GWT Aluminium tube to that tolerance every single day - they're very high speed rollers we use on our machines.
Surface finish is between around 1.5-1.8 ra, and then we have to balance them for running at speed too....
 
I've been asked at work the feasibility of cnc cylindrical grinding some aluminum parts. Material is either 6061 or 7075 likely T6 temper (I was not given more details than that). The parts are about 113" long and the OD is a little over 5". The entire OD needs to be ground to 5.XXX" +/- .001". To make matters more difficult the wall thickness is in the ballpark of .25". Is there anyone here that dare touch this job with a 10' pole and if so how would you go about it?

I'm fairly fresh to the world of grinding and any input or experience you can share with grinding aluminum is greatly appreciated even if it doesn't quite relate to my question. I'm interested to learn whatever I can.

I have access to machines that run 20" and 30" OD wheels, are just barely long enough to support the part on centers, and I have steady rests I can set up for additional support.

Sent from my SM-G960U using Tapatalk

That would be a good candidate for centerless grinding, I've had 12' lengths of 2" dia 1/4 wall tubing centerless ground, 5" might be larger than the guys I used could handle, but i bet there's plenty around who could.


Finish wasn't great, but I didn't need it to be. I'm sure with care it could have been a lot better (different wheel/coolant etc etc), but that wasn't required.
 
Why use grinding?
We turn 2500mm long,120mm diameter, 8mm GWT Aluminium tube to that tolerance every single day - they're very high speed rollers we use on our machines.
Surface finish is between around 1.5-1.8 ra, and then we have to balance them for running at speed too....
That is an incredibly similar example. I found out today that they are currently polishing in the machine by hand post turn because the entire OD requires a 16ra (microinches), .4ra (micrometers). I don't have many details on what has been so hard for them but I can say we aren't a shop that runs a lot of aluminum. Our primary focus has almost always been oil, gas, and aerospace. We deal with a lot more steel alloys and Inconels than anything else. Aluminum jobs have become more prevalent in the last 5 years or so but its never a large workload of it. But I have no turning experience so I shall not cast stones from where I spin them.

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That would be a good candidate for centerless grinding, I've had 12' lengths of 2" dia 1/4 wall tubing centerless ground, 5" might be larger than the guys I used could handle, but i bet there's plenty around who could.


Finish wasn't great, but I didn't need it to be. I'm sure with care it could have been a lot better (different wheel/coolant etc etc), but that wasn't required.
I was informed today that they also need a 16 ra microinches finish. We have a centerless grinder that could likely run the parts however the coolant filtration system is damn near non existant and leaves score marks on some 718 parts we run that has the inspectors crying about deviations in a 32 ra finish.

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That is an incredibly similar example. I found out today that they are currently polishing in the machine by hand post turn because the entire OD requires a 16ra (microinches), .4ra (micrometers). I don't have many details on what has been so hard for them but I can say we aren't a shop that runs a lot of aluminum.
Call your tooling rep. and drop it in his/her lap.
Limited experience but I have never seen centerless grinding of aluminum. I'm sure it can be done but with what type wheels?
These grinding wheels not cheap at 20 and 30 inch. Your wheels for soft or hard steel are not going to work and if a centerless this size upset with wheel/part it lets you know big time.
Bob
 
Our primary focus has almost always been oil, gas, and aerospace. We deal with a lot more steel alloys and Inconels than anything else.

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Who do you work for, and why do you think you can get answers for nothing?
 
I'd fill it with sand, too. Trouble with centerless would be if it's got to be round and straight. We don't know ...

Do you know that trick with emery cloth and steady rests ? Soak the emery cloth in oil, put it between the steady and the part with the grit side facing out ?
 
Call your tooling rep. and drop it in his/her lap.
Limited experience but I have never seen centerless grinding of aluminum. I'm sure it can be done but with what type wheels?
These grinding wheels not cheap at 20 and 30 inch. Your wheels for soft or hard steel are not going to work and if a centerless this size upset with wheel/part it lets you know big time.
Bob

Like I said I've had it done, finish wasn't great, I assume they ran whatever wheel was in the machine. Some of the steel bar these guys have run for me didn't have a very fine finish either.

Mcmaster sells centerless ground aluminum rod ( McMaster-Carr ) so commercial sources are availible
 
Who do you work for, and why do you think you can get answers for nothing?
I don't expect to get answers for nothing. I am grateful and want to thank everyone for the responses.

For some backstory on me, I have been in the machining field for 8 years with no schooling. I have mostly hole making experience running homemade manual and cnc deep hole drilling machines, with hole sizes varying from 1"-14" in diameter and depths as deep as 400". Other than our indexable drills which we use exclusively for roughing work we design and make all our own tooling and even shafts in house. The last 3 years I've really specialized in development of our bottle boring processes.

I recently took an opportunity in grinding with the expectation to fill a huge hole that was left over here when the one guy we've relied on for grinding process development and programming left to work for himself in his home shop full time. I only have about a year and a half total grinding experience that has been spread over the last 5-6 years. I've never touched a lathe or a cnc mill. I've some very basic work on a manual mill and know barely enough to be dangerous. My experience is very limited and confined mostly to niche things that not many shops around here do. I took this position because I was getting bored and needed a new challenge and want to expand my knowledge. I have a mountain to learn here and I'm excited for it.

I as well as the project manager for this part are going to be talking to our wheel suppliers this week for their input too. When I was initially asked about grinding this part I thought it would be interesting to ask about here because it would be a challenge to grind in almost every aspect. Difficult material, thin wall, and long enough to make rigidity a challenge too.

I'm not looking for a free ride. I'm here to learn what I can from those who would like to offer ideas.

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ZEP, pay no attention to the village idiot/Ayn Rander. The vast majority of us are happy to share knowledge when requested, especially when it's a challenging problem that gets the brain cells working.

And then, some just want attention. "Throw a rock through your window" attention. Best to ignore them, replies just feed them.
 
I don't expect to get answers for nothing. I am grateful and want to thank everyone for the responses.

For some backstory on me, I have been in the machining field for 8 years with no schooling. I have mostly hole making experience running homemade manual and cnc deep hole drilling machines, with hole sizes varying from 1"-14" in diameter and depths as deep as 400". Other than our indexable drills which we use exclusively for roughing work we design and make all our own tooling and even shafts in house. The last 3 years I've really specialized in development of our bottle boring processes.

I recently took an opportunity in grinding with the expectation to fill a huge hole that was left over here when the one guy we've relied on for grinding process development and programming left to work for himself in his home shop full time. I only have about a year and a half total grinding experience that has been spread over the last 5-6 years. I've never touched a lathe or a cnc mill. I've some very basic work on a manual mill and know barely enough to be dangerous. My experience is very limited and confined mostly to niche things that not many shops around here do. I took this position because I was getting bored and needed a new challenge and want to expand my knowledge. I have a mountain to learn here and I'm excited for it.

I as well as the project manager for this part are going to be talking to our wheel suppliers this week for their input too. When I was initially asked about grinding this part I thought it would be interesting to ask about here because it would be a challenge to grind in almost every aspect. Difficult material, thin wall, and long enough to make rigidity a challenge too.

I'm not looking for a free ride. I'm here to learn what I can from those who would like to offer ideas.

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You did not answer my question.

Who is this for? and why is it done in the Aland Islands?
 
otrlt, the man is asking about a process. If you are not smart enough to answer the question why are you posting?

None of your business who it's for. Aland Islands is apparently a default when no location is posted.
 
{I've been asked at work the feasibility of cnc cylindrical grinding some aluminum parts.}
{I'm fairly fresh to the world of grinding and...}

I think it is not very feasible, getting close to size/finishing skim wheel dressing can be a great aid to avoid the last pass galling the work with stuck particles. I guess I would call Radiac and ask their tech guy about that.

Turn to + .0008 and finish with abrasive paper or polishing device might be best.
 








 
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