Just can't get any sort of good finish boring aluminum on lathe - tips?

[K&Y]

Originally Posted by msomerville If you are doing low volume parts I would stay away from PCD. There is no reason that you can't achieve the finish you need with the right insert and boring bar. There is an insert I use from www.toolmex.com it is a ccgt-ak high polish insert that might do the trick with a slightly bigger boring bar. Really you should be able to get it with the size you have.

That's the problem. You cannot get a better finish when comparing carbide and PCD. And as I alluded to earlier, it really depends on the amount of inserts that you are going through, and what results you want to achieve as far as making a choice between PCD and carbide.

[DareBee]

Take it easy K&Y.
I said it was hard to justify. Not that it should never be done.
Your points made are valid.
Jumping on my head as an instigator is not.

I can get a 16um finish with a $15 carbide that has 2 cutting tips on my Taiwanese lathe, That is all I was saying.

Turning exotics and hard tool steel with any efficiency requires high end tooling and experience has shown me that trying to "cheap out" rarely works.

[K&Y]

Originally Posted by DareBee Take it easy K&Y. I said it was hard to justify. Not that it should never be done. Your points made are valid. Jumping on my head as an instigator is not. I can get a 16um finish with a $15 carbide that has 2 cutting tips on my Taiwanese lathe, That is all I was saying. Turning exotics and hard tool steel with any efficiency requires high end tooling and experience has shown me that trying to "cheap out" rarely works.

DareBee, I didn't jump on your head, and I apologize if you got that impression, as it was not my intent.

What I AM trying to get across, is exactly what you said in your last sentence. Basically, you get out what you put in. It's just a matter of the particular user wanting to get a superior product. If that's the case, then they should investigate all the options and not turn a blind eye.

16um finish isn't bad for a $15.00 carbide tip. You should be able to attain 3 to 4 um consistently with a PCD insert. A natural or Monodie diamond insert would give you .5 um finish minimum, but that would only be necessary if you were seeking an optical finish on your product.

By the way, I am very curious as to where you came up with the price of $90.00 per insert, as it seems quite excessive. The PCD insert in question for this application should not cost more than $38.00-$40.00 (US).

[DareBee]

I must apologize I was thinking of CBN inserts which run between 90 and 130 each from Sowa. Not sure if there is much difference between them but they must be somewhat similar.
Maybe I should be switching suppliers for my hard turning inserts.

[big_mak]

I would say the bigger the bar the better. I think 0.1" DOC is pretty steep for a 3/8" Bar. Maybe 0.02" with higher feed rates. Load it up and shut it up.

[ctate2000]

Hu Flung is correct. Go to larger bar.

[DareBee]

Hu Flung?

[ctate2000]

Sorry, DareBee. not Hu.

[DareBee]

Well - we are both Canucks ;-)
Live about 2500 mi apart though.

[cam1]

Hi: We do alot of 6061T6, and use the ccgt-ak type inserts, which are superb for aluminium, (we also use them on Stainless for finish passes).These cutters "scoop" the material out. Since switching to these cutters for Al we achieve mirror like finishes, and hit the numbers every time.

regards

[neilw20]

I use those nice shiney ones too. They are great. Specially meant for aluminum too.