Thread: Machining Aluminium With Carbides Surface Finish

I'm no guru but they look good to me the one on the right look's best. You can see where you stopped but still look good to me.
David

Hi Justin,

Looks ok, for manual feed, I think it might possible to get bit better finish, I find metho works better as a cutting lubricant for aluminium, also, the inserts for aluminium need to be the right type, I think they need to the high rake angle type, pictured below.




I've got some of these coming shortly for a a trial on mild steel, but they are really intended for use on aluminium.

Regards
Ray

I think you are 100% correct Ray.

Long story short I was machining steel and was a bit lazy to swap tools.
I have machined aluminium with carbides before but I went to some extra effort of surface finish just for the fun of it.

I think the high rake tool would be better as it's doesn't "feel" right when maching and the chips are a little odd. You can feel it kinda pushing then cutting.

I prefer a properly sharpened HSS bit and can get a far superior finish. Never tried metho or kero, I should try that.

Might look into the high rake tool only catch is most places only sell 10 at a time.

Cheers

Justin

I'm not fussed on using carbide for machining aluminium. The high raked angles as shown (carbide) are the only style to use. I find the biggest problem with carbide is to obtain a razor sharp cutting edge. If time is no value, I would try using HSS with cobalt and grind the tool with a high rake angle. I would use the same speed in rpm but the speed depends on the rigidity of the lathe spindle, the radius on the tip of the tool bit and the clearance angle at the front edge of the tool. I have never tried using metho as a lubricant, I have always used kero or diesel fuel. If you have lots of these parts to do, I would use soluable oil as a lubricant. There are many different kinds of soluable oil on the market so I can't advise you on a particular one to try. It is also very important to have the top of the tool surface where the swarf slides, be highly polished. Any grinding marks on this surface will result in the HSS ( and even carbide) "picking up" in the minute grooves produced by the grit of the grinding wheel. The aluminium will rapidly build up on the tool tip to the point where the tool will not work without scoring the job very badly.
The main thing is to have good clearance and rake angles and razor sharp tools. The sharpest cutting edge can only be obtained with HSS (from years of experience).

Hi Justin,

Those high rake diamond inserts I mentioned arrived, and I've put some pictures in the diamond tool holder thread.

They are great on mild steel, and of course brilliant mirror finish on brass and aluminium.

Regards
Ray

I have re-read this post a few times yet do not see any pics of Ali only the cutter shown

Hi Ray,

There are some pictures of mild steel in the other thread that I referred to, I didn't take any pictures of Aluminium...

Regards
Ray

Hi Ray
It's great to see that you have had excellent success with the carbide inserts, keep up the good work.

Originally Posted by RayG

Hi Justin,

Those high rake diamond inserts I mentioned arrived, and I've put some pictures in the diamond tool holder thread.

They are great on mild steel, and of course brilliant mirror finish on brass and aluminium.

Regards
Ray

Interesting. I've always read brass needs zero rake. Not so with carbide?

Originally Posted by RayG

Hi Ray,

There are some pictures of mild steel in the other thread that I referred to, I didn't take any pictures of Aluminium...

Regards
Ray

Hi Ray not your post but Justins original 1st post he says about photo's below I don't see any.

Originally Posted by wheelinround

Hi Ray not your post but Justins original 1st post he says about photo's below I don't see any.

Hi Ray,

The url for those pictures is this one...

http://i638.photobucket.com/albums/u...u/6f880281.jpg

I can see them ok, so it might be blocked from your side somewhere?

Regards
Ray

TY Ray

Originally Posted by Bryan

Interesting. I've always read brass needs zero rake. Not so with carbide?

Hi Bryan,

That's true for HSS, I'm not so sure about carbide, other than the sharper edge with those inserts seems to give a nicer cutting action. The "rule of thumb" that I read somewhere, is that the DOC should be greater than one and a half times the nose radius (for carbide at least).. with "doughy" steel it seems to just roll up into little balls and just ploughs through the steel rather than cutting, these sharper inserts seem to overcome that problem...


For the sake of interest, the angles for HSS are the ones in the table below..




Regards
Ray

Thanks for the update Ray.

I think I'll look into those inserts.

Cheers

Justin