Best ball or bull for Ti6Al4V?

What's the best kind of ball or bull for mold-type surfacing / Kellering of organic-shaped surfaces in Ti? Doing orthopedic plates and need to keep tool pressure low so the plate doesn't deflect and chatter too much but I'd like to be able to cut some cycle time on the finishing. I like the "tapered reach" mold finishers that Harvey has, but they only make 2-flute and my gut tells me with Ti I should be using more flutes. Thanks!

I'd vote bull for the better cutting edge geometry and surface speed. Minimize rubbing, proper chip clearance, etc. More flutes, less engagement if you can do it, I've bought a bunch of "tulip" style cutters with eight flutes and radius corners for this purpose.

And trying to answer the question better, perhaps you can get some specials made that will incorporate the size you need along with multi-flute geometry. If this is a long term issue it's worth getting exactly what you need.

The cutters I mentioned before are all larger, meant for things like aircraft structural parts.

Any chance that any portion of the mold geometry would lend itself to using a circle segment cutter?

e.g. Circle Segment Cutters | Emuge Corporation

PM

precisionmetal said:

Any chance that any portion of the mold geometry would lend itself to using a circle segment cutter?

e.g. Circle Segment Cutters | Emuge Corporation

PM

Click to expand...

I could theoretically do the outside with one, but I could also use the side of a flat endmill since it's all convex. My trunnion doesn't index very quickly though, so when I tried it didn't save any cycle time over using an 1/8" ball. The inside is concave, kind of spoon shaped, so I need a ball or bull for that anyway. I also tried a 1/4" bull with .060" radius, and that seems to work fine when the tool is sharp, but once it starts to dull I get a lot of chatter.

Here's what my setup looks like, though this is an older revision plate:

I would strongly suggest that you reach out to Seco for cutters of this type. More specifically, you may want to call Niagara Cutter, and ask to speak with their "Solid Tools Specialist" for your area.

Seco owns Niagara Cutter now, so Seco has the "Niagara" line of endmills made in Pennsylvania, but also their "Jabro" line of endmills, made in Lottum, Netherlands.

Jabro is known for making very high-end endmills, most of them tailor-made for a specific task. Niagara has been investing heavily into their lineup for a few years, and they have some really capable tools now that may even be the "perfect fit" for your job. Regardless, I'd reach out and speak with one of the "Solid Tools Specialists" who focuses on endmills only. They will be more than capable of helping you find the best tool for the job. Their solid tool's specialists have some seriously impressive knowledge, and lots of experience with aerospace & medical milling, including titanium. I think you'll be impressed.



Full disclosure, I used to work for Seco, and currently work for a tooling distributor that sells Seco & Niagara. However, I don't sell in your area, and I think you'll be doing yourself a dis-service if you don't check them out. Good folks, and good tools.

All the best.

Seco/Niagara has some good stuff, I've always had good luck with their carbide.

I used Kennametal's "Harvi" endmill line last summer on a Ti project with good success. Somewhat similar situation to you in that I had no flat surfaces on the part, all done in 3+2 or full 5 surfacing. I like that they have a good flute count so you can increase your feed rates quite a bit over those 2 flutes.

High-Performance Solid Carbide End Mills • HARVI™

Thanks, I'll look into those.