Indexable Tooling

[SAWMANParticipant @sawman]

Old Git, New Tooling

[SAWMANParticipant @sawman]

Although I served an engineering apprenticeship with the Atomic Energy Authority some 40 years ago, I have only recently been able to equip a home workshop with a lathe (Chester Centurion) and mill (Warco VMB).

 

I’ve bought some Glanze Indexable tooling for the mill, but I find when I use it that enormous burrs are created which take a lot of filing to remove. I’ve tried machining gunmetal and mild steel, with the same results. Cast Iron seems to be OK.

 

Is this normal or am I doing something wrong? Any help would be much appreciated.

[JasonBModerator @jasonb]

Not normal check the tool is on centre height as thats the usual culprit.

 

Jason

 

PS you may want to look through some of the recent (last 2-3 week) posts on teh same subject and also the “turning trials” threads

 

J

[mickParticipant @mick65121]

If this occuring while milling there are a couple of possibilities:

Wrong grade of insert and rake angle. A good positive rake will lift the swarf chips clear in a sprial flow

Tips are blunt, carbide is very brittle and will easily chip is used incorrectly

Are you running at the correct RPM and feed, as if the inserts are revolving two slowly they will start rubbing and blunt.

As cast dosn’t create swarf, only fine chips there won’t be a burr.

I assume the spindle is rotating clockwise and you are using a coolant or cutting oil.

[SAWMANParticipant @sawman]

Thanks for the useful advice. The inserts are those that were supplied with the end mill, so I presume that they are the right ones. I have examined the inserts with a magnifying glass and they appeared to be OK. One had possibly worn compared to the other two, but I’ve indexed them all round to expose a new face and this has improved the problem, but I still get burrs. Spindle speed is about 1400 rpm, feed rate is very low and I’m using a light machine oil for lubrication. The surface finish is excellent by the way.

 

S

[Ian S CParticipant @iansc]

SAWMAN, when I got my vertical mill, I knew nothing about milling machines(Iknow less now), and I bought a 50 mm face cutter with 3, 16 mm tryangular cutters, I asked how best to use it, and the store “expert” just said give it about a MM of cut, set the speed at 900rpm, and crank like hell. The inserts that were supplied with the cutter had a chip breaker groove, but when I went to another supplier for replacements, the chap there told me that the problems I had with the tips chipping was because of the chip breaker. The tips recomended are plain flat topped and they work well. The old worn ones are reground and used in the lathe. Most work is done dry, some times I use soluble cutting oil. Ian S C

[WeldsolParticipant @weldsol]

It could be that you are lubricating the cutter rather than letting it cut so you could be swaging some of the metal up to make the burrs.

I always cut dry on my Bridgeport when using carbide tips the alternative is to flood cool them with cutting oil (can be messy)

 

Paul

[Anonymous]

Posted by SAWMAN on 04/07/2011 12:12:01:

Spindle speed is about 1400 rpm, feed rate is very low and I’m using a light machine oil for lubrication.

 

Therein lies your problem I think. If the feedrate is low the inserts will simply rub rather than cut, and produce a burr. Assuming that the tool is a small face mill let’s be conservative and set a chip load of 3 thou per insert per rev. Three (?) inserts makes 9 thou per rev for the tool. At 1400rpm that’s 12.6inches/min. That’s a fair cranking rate. General rule for carbide; give it some wellie! Plenty of speed and feed.

 

I suspect that using a light machine oil isn’t achieving anything, apart from generating a bit of niff. As has been said by Paul either cut dry, or use flood coolant, primarily to get rid of the chips.

 

Regards,

 

Andrew

[Author]

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