Anodizing Knurled Aluminum help needed.

Mirage_Man · Apr 18, 2007

I am hoping someone can help me out here.

I have some aluminum parts that I had run by a CNC shop. They used a forming knulring tool to make a diamond knurl pattern. It looks nice. However After having it anodized there are small particles in the grooves which are coming off revealing bare aluminum. It's obvious that the particles have been mashed into the grooved during forming regardless of the fact that flood coolant was used.

What I'd like to know is what can be done to eliminate or at least minimize this problem? I did use a scrub brush on the parts prior to plating but apparently it didn't get enough out. Maybe the bristles weren't small enough to get into the grooves? I tried taking pictures to show but the camera just doesn't capture what the naked eye easily sees.

I had a thought that an ultrsonic cleaner might help loosen the particles but I can't get anyone on the phone from one of the ultrsonic cleaner makers to ask. I keep getting voice mails.

If anyone has experience or tips I sure would appreciate it.

Thanks!

Mirage_Man · Apr 18, 2007

I am hoping someone can help me out here.

I have some aluminum parts that I had run by a CNC shop. They used a forming knulring tool to make a diamond knurl pattern. It looks nice. However After having it anodized there are small particles in the grooves which are coming off revealing bare aluminum. It's obvious that the particles have been mashed into the grooved during forming regardless of the fact that flood coolant was used.

What I'd like to know is what can be done to eliminate or at least minimize this problem? I did use a scrub brush on the parts prior to plating but apparently it didn't get enough out. Maybe the bristles weren't small enough to get into the grooves? I tried taking pictures to show but the camera just doesn't capture what the naked eye easily sees.

I had a thought that an ultrsonic cleaner might help loosen the particles but I can't get anyone on the phone from one of the ultrsonic cleaner makers to ask. I keep getting voice mails.

If anyone has experience or tips I sure would appreciate it.

Thanks!

Mirage_Man · Apr 18, 2007

I am hoping someone can help me out here.

I have some aluminum parts that I had run by a CNC shop. They used a forming knulring tool to make a diamond knurl pattern. It looks nice. However After having it anodized there are small particles in the grooves which are coming off revealing bare aluminum. It's obvious that the particles have been mashed into the grooved during forming regardless of the fact that flood coolant was used.

What I'd like to know is what can be done to eliminate or at least minimize this problem? I did use a scrub brush on the parts prior to plating but apparently it didn't get enough out. Maybe the bristles weren't small enough to get into the grooves? I tried taking pictures to show but the camera just doesn't capture what the naked eye easily sees.

I had a thought that an ultrsonic cleaner might help loosen the particles but I can't get anyone on the phone from one of the ultrsonic cleaner makers to ask. I keep getting voice mails.

If anyone has experience or tips I sure would appreciate it.

Thanks!

L Vanice · Apr 18, 2007

You could try abrasive blasting or a fine wire wheel. Be careful not to mess up the knurling. You will be bound to round off the top points at least a little bit, so the key will be to do it uniformly.

I suppose there is also a chance that some air bubbles were trapped in the grooves, leaving bright spots.

Larry

L Vanice · Apr 18, 2007

You could try abrasive blasting or a fine wire wheel. Be careful not to mess up the knurling. You will be bound to round off the top points at least a little bit, so the key will be to do it uniformly.

I suppose there is also a chance that some air bubbles were trapped in the grooves, leaving bright spots.

Larry

L Vanice · Apr 18, 2007

You could try abrasive blasting or a fine wire wheel. Be careful not to mess up the knurling. You will be bound to round off the top points at least a little bit, so the key will be to do it uniformly.

I suppose there is also a chance that some air bubbles were trapped in the grooves, leaving bright spots.

Larry

Dave(Spooky) · Apr 18, 2007

Hiya Mirage,

I had the same sort of problem with some Moderator body tubes.A quick spend later and an ultrasonic cleaner sorted all the problems.Even using decent cut knurl tools I still managed to get flecks in the finish till I got my US tank.
Another way (this is probably against all H&S rules) is to fine dry blast with beach sand.(Yup the stuff you get from the beach)at about 30 psi.This keeps the peaks on the knurls but helps to remove the flecking.
Be aware though,the dust from silicon sand is pretty nasty...etc etc etc...you get the point I'm sure

In some cases those flecks will actually anodise then fall out later leaving spots,worse case is when the spots then corrode!! you end up with bigger white corrosion spots

Another good way is to wash the parts in Petrol (Gasoline?) very illegal and probably dangerous (insert don't sue me plea here) but it does work on some of the grease locked flecks.
Boiling water is also another option (if you don't wanna buy the US tank) the expansion rates of the fleck to the rate of the body is often quite different and will help losen them.
Whatever way you try you can be sure when you think it's perfect you will get a crital /late job that goes back to flecking

cheers Dave

Dave(Spooky) · Apr 18, 2007

Hiya Mirage,

I had the same sort of problem with some Moderator body tubes.A quick spend later and an ultrasonic cleaner sorted all the problems.Even using decent cut knurl tools I still managed to get flecks in the finish till I got my US tank.
Another way (this is probably against all H&S rules) is to fine dry blast with beach sand.(Yup the stuff you get from the beach)at about 30 psi.This keeps the peaks on the knurls but helps to remove the flecking.
Be aware though,the dust from silicon sand is pretty nasty...etc etc etc...you get the point I'm sure

In some cases those flecks will actually anodise then fall out later leaving spots,worse case is when the spots then corrode!! you end up with bigger white corrosion spots

Another good way is to wash the parts in Petrol (Gasoline?) very illegal and probably dangerous (insert don't sue me plea here) but it does work on some of the grease locked flecks.
Boiling water is also another option (if you don't wanna buy the US tank) the expansion rates of the fleck to the rate of the body is often quite different and will help losen them.
Whatever way you try you can be sure when you think it's perfect you will get a crital /late job that goes back to flecking

cheers Dave

Dave(Spooky) · Apr 18, 2007

Hiya Mirage,

I had the same sort of problem with some Moderator body tubes.A quick spend later and an ultrasonic cleaner sorted all the problems.Even using decent cut knurl tools I still managed to get flecks in the finish till I got my US tank.
Another way (this is probably against all H&S rules) is to fine dry blast with beach sand.(Yup the stuff you get from the beach)at about 30 psi.This keeps the peaks on the knurls but helps to remove the flecking.
Be aware though,the dust from silicon sand is pretty nasty...etc etc etc...you get the point I'm sure

In some cases those flecks will actually anodise then fall out later leaving spots,worse case is when the spots then corrode!! you end up with bigger white corrosion spots

Another good way is to wash the parts in Petrol (Gasoline?) very illegal and probably dangerous (insert don't sue me plea here) but it does work on some of the grease locked flecks.
Boiling water is also another option (if you don't wanna buy the US tank) the expansion rates of the fleck to the rate of the body is often quite different and will help losen them.
Whatever way you try you can be sure when you think it's perfect you will get a crital /late job that goes back to flecking

cheers Dave

Mirage_Man · Apr 20, 2007

Thanks for the replies everyone.

Here's an update... I spent a couple hours on the phone yesterday talking to machine and finishing shops. The general consensus was that a mechanical method is the only way to really get those particles out.

I stopped by a machine shop where a friend works and used their ultrasonic cleaner. It did nothing but clean the part. The particles were still there.

So last night I got a little brass wire brush. I put the part back in the lathe and spun it at about 500rpm while moving the brush back and forth over it. I turned in both forward and reverse with a little WD40. Then I hit it with some scotch brite.

It appears most if not all the flakes are now gone!

So this is good news and bad. The good news is I can get the flakes out. The bad news is I have to do this to 100 parts! :eek:

Next time I run these parts you can bet I'll have worked out a way to knurl that won't produce this problem.

Mirage_Man · Apr 20, 2007

Thanks for the replies everyone.

Here's an update... I spent a couple hours on the phone yesterday talking to machine and finishing shops. The general consensus was that a mechanical method is the only way to really get those particles out.

I stopped by a machine shop where a friend works and used their ultrasonic cleaner. It did nothing but clean the part. The particles were still there.

So last night I got a little brass wire brush. I put the part back in the lathe and spun it at about 500rpm while moving the brush back and forth over it. I turned in both forward and reverse with a little WD40. Then I hit it with some scotch brite.

It appears most if not all the flakes are now gone!

So this is good news and bad. The good news is I can get the flakes out. The bad news is I have to do this to 100 parts! :eek:

Next time I run these parts you can bet I'll have worked out a way to knurl that won't produce this problem.

Mirage_Man · Apr 20, 2007

Thanks for the replies everyone.

Here's an update... I spent a couple hours on the phone yesterday talking to machine and finishing shops. The general consensus was that a mechanical method is the only way to really get those particles out.

I stopped by a machine shop where a friend works and used their ultrasonic cleaner. It did nothing but clean the part. The particles were still there.

So last night I got a little brass wire brush. I put the part back in the lathe and spun it at about 500rpm while moving the brush back and forth over it. I turned in both forward and reverse with a little WD40. Then I hit it with some scotch brite.

It appears most if not all the flakes are now gone!

So this is good news and bad. The good news is I can get the flakes out. The bad news is I have to do this to 100 parts! :eek:

Next time I run these parts you can bet I'll have worked out a way to knurl that won't produce this problem.

Mud · Apr 20, 2007

FWIW at this point, be careful bead blasting before anodizing. We had horrible results on some costly parts that were glass beaded befor eanodizing, and the anodizer blamed the bead blasting. I'm unsure if it was media or pressure related, every anodizer has a different take on the situation it seems.

Mud · Apr 20, 2007

FWIW at this point, be careful bead blasting before anodizing. We had horrible results on some costly parts that were glass beaded befor eanodizing, and the anodizer blamed the bead blasting. I'm unsure if it was media or pressure related, every anodizer has a different take on the situation it seems.

Mud · Apr 20, 2007

FWIW at this point, be careful bead blasting before anodizing. We had horrible results on some costly parts that were glass beaded befor eanodizing, and the anodizer blamed the bead blasting. I'm unsure if it was media or pressure related, every anodizer has a different take on the situation it seems.

Tumbleweed Tim · Apr 20, 2007

Plating twice will help. Plate/strip/plate. Best thing to do is not over form the knurl. The work hardened tips break off. That’s what those flecks are from. Use a loop and set your tool so it rolls just under a full pattern. Like 90% full. Best to use as much coolant as you possibly can and convex knurls if your feeding. If you have high volume you don't have time to examine/rework every part and they all have to be good first time.

Tumbleweed Tim · Apr 20, 2007

Plating twice will help. Plate/strip/plate. Best thing to do is not over form the knurl. The work hardened tips break off. That’s what those flecks are from. Use a loop and set your tool so it rolls just under a full pattern. Like 90% full. Best to use as much coolant as you possibly can and convex knurls if your feeding. If you have high volume you don't have time to examine/rework every part and they all have to be good first time.

Tumbleweed Tim · Apr 20, 2007

Plating twice will help. Plate/strip/plate. Best thing to do is not over form the knurl. The work hardened tips break off. That’s what those flecks are from. Use a loop and set your tool so it rolls just under a full pattern. Like 90% full. Best to use as much coolant as you possibly can and convex knurls if your feeding. If you have high volume you don't have time to examine/rework every part and they all have to be good first time.

Anodizing Knurled Aluminum help needed.

Aluminum

Aluminum

Aluminum

Diamond

Diamond

Diamond

Aluminum

Aluminum

Aluminum

Aluminum

Aluminum

Aluminum

Diamond

Diamond

Diamond

Stainless

Stainless

Stainless

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