Long, thin endmill deflection

[Jmeyers]

Hi,

A part I'm doing requires me to make some pretty tricky contours. The part is 15/16 thick 4140 prehard, and I need to cut notches in from the sides, about 5/16 into the side, the full depth, that have a .055 radius at the inside. they taper out/ bellmouth a bit, the best way i can think of to describe it is that it's similar to the valley between 2 teeth off a rack gear. The whole profile needs to be accurate, so i can't just clearance the bottom with a drill. other part constraints prevent me from cutting it in a different orientation, and i don't have an edm machine or any of the other smarter ways to cut this. The machine i'm working on is a haas vertical and the toolholder is an er32 collet chuck.

 

The endmill i've been working with is a 3/32 necked endmill, 12x reach, from harvey tool. I'm working on a test block, taking finish passes, and i'm finding that it deflects a lot, and that i need to take several spring passes to get it to cut without a taper. My feed, speed, and axial depth of cut are out of the book. I've tried conventional passes, and they help but don't solve it. Are there any other tricks i haven't thought of for this situation? Also, if anyone has cut a similar feature and could post parameters that worked, i'd appreciate it.

 

 

Thanks.

-Jason

[GoetzInd]

Are there any other tricks i haven't thought of for this situation?

 

Wire EDM?????

 

Have you looked into the dynamic core toolpaths. I would be using that and a bunch of spring passes if I'm picturing your parth correctly.

[Brando]

any opitions for different tool holder ? ilike a er16 or a er20? they would prob work better for a smaller tool, and get more of shorter lengths ex. 2xd 6xd 8xd 10xd of tools and do it in steps leaving the 12xd to do only the deepest, not gonna get away from deflection take smaller doc to reduce cutting forces

static tool runout less then .0002 at tip , and max spindle speed is not always the best,

find a speed that produces the least amount of vibration at the spindle head , this will help protect the cutting edge and ensure there is not any dynamic runout out from vibration

 

pretty much all i have to offer

[mig]

 

find a speed that produces the least amount of vibration at the spindle head , this will help protect the cutting edge and ensure there is not any dynamic runout out from vibration

 

Also i woud go for smaller DOC but faster feed.