Flycutter Carbide Insert Life

[devils4ever]

I've been using my Tormach Superfly cutter to bring to dimension some 1018 steel blocks. The blocks are 1.250" square X 4" long. I'm removing 0.025" from each side to bring it down to 1.200". Each pass is about 0.005" DOC.

Well, the first side with a new carbide insert is like a mirror. Beautiful! By the time I get to the last side, the cutter has obviously dulled and the finish is dull and matted. I would assume the carbide cutters would last a lot longer than this. The inserts are Korloy SEHT1204AFSN-X45.

Does this seem correct? Should they last longer? Are there better inserts?

 

[Mitch Alsup]

How many RPMs?
What is the distance of tip from center of rotation?
What kind of lube?
How many linear inches per minute?
What is the tip raidus on the insert?

 

[mattthemuppet2]

any reason you're using a fly cutter specifically? I'd use a 1/2" rougher at finish depth and step over 1/4" or 3/8" every pass. Be a lot quicker that 10 passes at 0.005". Even better would be a face mill using the same inserts, one or 2 passes would get it done.

My guess as to why your insert is dying is too shallow a DOC and the interrupted cuts. Basically your insert is BANG rub BANG rub all the way along the work. Try slowing the spindle down to 100-200rpm and increase the DOC to 0.01" at least.

 

[devils4ever]

Mitch: ~500 RPMs, 1.25" radius (2.5" diameter), Tap Magic, 6 IPM, looks flat with no radius.

Matt: I like the finish the fly cutter gives and I think it's faster on my small (PM-25) mill. I have to take light cuts either way. Heavier cuts on this mini-mill makes it very unhappy. I don't have a face mill.

I have some wider stock 4" and 6" that I need to take off 0.015" on. I'll try slowing down the fly cutter. I may try my 3/4" end mill to compare the finish and completion time.

 

[Lo-Fi]

That's way, way, way too slow for carbide. Crank up the RPM, you should be around the 1500 mark for that diameter. Don't be afraid of driving it hard, it's what it's designed for, and it doesn't care about heat. What carbide doesn't like is slow speed gouging through material. It cracks pretty quickly when driven like that. Give it a go, you'll get an even better surface finish too.

 

[mikey]

Cutting speed for that insert is ~500-1000 sfm. I use about 800sfm for low carbon steel and find it to work okay. This should give you about 1200 rpm at that diameter. Your mill should easily be able to handle a 0.010 - 0.020" deep cut per pass. Feed is 0.007IPT or about 8 IPM; modify this to keep the insert throwing a chip or finish will suffer. Some cutting oil will help.

My Superfly is still on the original insert and still going strong. The correct speed and feed matters so experiment with these until you find what works on your mill.

 

[mattthemuppet2]

2.5" is a pretty big tool for a small mill. Can you "neck it down" to reduce the radius? I also don't think that the interrupted cut as the insert bangs into the edge of the work is doing it many favours. Maybe take off the bulk of the material with a 3/8" rougher and then a finish pass with the fly cutter. Or if you want a beautiful finish with a small DOC, the ground inserts (SEKT?), will work well though they're less robust than the molded ones you have.

 

[devils4ever]

I might be able to reduce the radius a little, but not that much.

I guess I'll have to play with it a bit to see what works. Higher RPMs, slower RPMs, faster feed, slower feed, bigger DOC, etc......

 

[mikey]

Your flycutter was designed to work with a small, light mill like a Tormach 440 that has only 3/4 hp so it should work fine on your machine. Most important is nailing down the speed so I would start there. Adjust feed so you have a continuous stream of chips coming off the tool. You have to take enough depth of cut to avoid deflection due to the large and wide nose on the insert so try at least 0.010" and your insert will live longer.