Indexable Face Mill Troubles

[wawoodman]

Just a guess, those multiple insert cutters seem to run best when more than one insert is engaged in the work. If one cutter leaves the work before the next one engages, there is a bounce introduced which will destroy finish.

You can avoid this by cutting on one side of the cutter, not down the middle.

Then how come a fly cutter seems to work so well? (Not challenging, just asking.)

 

[4GSR]

thanks for the help 4gsr, i was looking at those, but don't they have a wiper flat as well??

Yes, they do, but they have a little bit different geometry on the cutting tip. Plus they don't have as much honed edge to them as the SEHT's do. Buy a few and try them before buying a whole pack. I didn't find any with a radius edge either. I guess they don't make them with a radius. My face mill uses the same insert but without the hole, clamp on style. I have a few with radius edges. Most of my inserts are the wiper type that I use with the face mill I have.

EDIT: Just curious, what RPM and feed rate are you using?

 

[springer]

Ok I'll give them a try. Worst case, I end up with 20 inserts I could try to make a the tool holder for. Dunno.

As for feed and speed, I've tried many different combinations without improvement. For feed rate on my superfly cutter, I run as fast as I can without harsh sounding hits on each revolution. I'm really impressed with it and figured this face mill would show it up. Not yet I guess

 

[T Bredehoft]

Mike, I don't know. I don't use a fly cutter, I'm not working toward finish, but dimension, I don't care what it looks like. When you run a multi-cutter tool off center, one cutter is either just entering the work or just leaving it, keeping torque on the spindle. A fly cutter may have all the bounce worked out before it re-enters the work. As I said I don't know.

 

[derf]

A multiple insert tool works better when you use ground inserts. I suspect the grade you have is general pupose.

 

[coolidge]

I looked up those inserts, they are labeled "For high speed milling of steel and stainless steel". You really have to do your homework on inserts because an insert of a certain geometry, carbide grade, coating can absolutely suck ass if you are not using it in the way it was designed to be used e.g. speeds, feeds, coolant/dry etc.

Recommend you go back and examine your setup. There's no reason for the part to be sticking out the side of your vice, it looks like you are clamping on a pointed edge, make some soft jaws with a V groove if you need to. If you want to mill steel like that put the part in a death grip. Lock the Z gib and the Y gib, lock the spindle, mill against/into the backlash on X. Rigidity is king.

Here are the Iscar inserts I'm using in my Glacern 45 degree face mill. Mine is a 2.5 inch 5 insert face mill. I see yours only has 3 inserts so yeah its going to beat things to death given the interrupted cut. This first insert works well on steel, nice tan to blue chips.


This razor sharp polished insert works well on aluminum, brass, non-ferrous, and plastics.


Here is a steel T-nut I machined to thickness with the above inserts.



Here is a link to the Iscar grade chart pdf file http://www.iscar.com/Ecat/EN/iscar_grade_chart.pdf

 

[springer]

It is a round part and I have everything as tight as I can. It is only hanging out of the vise about .120" so I can get calipers on it as I cut.

I get having a 3 insert cutter creates an interrupted cut, but no worse than my fly cutter would with only a single insert. I'm going to order different inserts. I use my insert for aluminum on my fly cutter (like yours posted above) and it works fantastic. It is 303 stainless so it machines easy which is why I was shocked when these other inserts didn't work.

 

[coolidge]

Oh stainless then try the sharp polished insert I posted, both would probably work, the 928 would probably last longer. The stainless may be too gummy for the insert you are using. I hate insert selection its maddening. For round stock you could turn your V blocks on their side or machine some aluminum soft jaws, even a small V would improve clamping force. I have some stainless cut offs maybe I'll throw some in a vise later today and report back how my inserts worked.

 

[derf]

I showed this to my Iscar rep, turns out they don't make a ground insert in that style. He also said it's totally the wrong tool for your application. He recommended a tool that uses triagular inserts.
BTW, are you making a muzzle brake?

 

[chevydyl]

another thing worth mentioning I think, is don't be swayed by how the insert manufacture may label the geometry as "Roughing" or Medium Duty, I have a Bridgeport clone and ALWAYS use finishing inserts to Semi Finishing, they require less power, and sometimes have better shear charictaristics so it takes the load off the machine. for my badboy face mill I use a Mitsubishi ASX445 3" 6 tooth, the inserts resemble yours a little, and when I really want a mirror finish on steel I throw on an ACTUAL wiper insert, it doesn't look like the normal inserts its weird, it also hangs down about .008 below the other inserts so it makes its own finish cut after the other inserts make their cut. you can also run just 1 insert in your cutter body. or 2 if you have an even number. Fact is you don't have the power or rigidity to run certain insterts. neither do I, they are made for 20hp VMCs that don't have a lack of rigidity lol. you did do right by going with a 45deg cutter tho. the other guys are right, insert selection is tough, the Mitsubishi inserts I use are Cermets and cut most steels, cermets also don't like coolant or oils, I read that it can make them crack or whatever from shock, they work better with a little heat