Horsepower for a 3" Face Mill

I'm thinking about bidding on a 3" indexable face mill on ebay. But I'm sort of thinking it might be a a bit much for a 5hp bedmill with a rigid head.

I've been using a 2" Octomill and I've thought it's performed well....regretablly a part came out of the vise and it mashed an insert off and it's really gouged the seat. Not sure if humpty-dumpty here can be put back right. Plus I'd have to get someone to EDM out the broken harden screw.

80% of my works in aluminum and I tend to like to take a 0.150 DOC. Would my machine most likely be dragging with a 3" face mill?

I'd think 5hp is plenty to swing a 3" face mill. You didn't mention how many inserts, expected or desired RPM, and that stuff matters. What taper is the spindle NT40?

The spindle's a 40-Taper. It would be a 6 insert face mill (compared) to my current 4-insert octomill. I usually do 0.100-.150DOC, 40ipm at 2500 RPM's on my octomill, and it doesn't strain (not certain what that SFM is offhand). Just interested in what's the common wisdom is for 5hp motors.

Contact the manufacturer of your proposed cutter. They have all of that information on hand. Just tell them the HP, RPM, material, DOC, feedrate, surface finish requirements, etc. They will probably make other suggestions to optomize your process and/or suggest a more appropriate cutter for your application. This is of course assuming you are buying a name brand cutter like Kennametal or Valenite, and not a no-name USA or import cutter.

If this is for a production situation, then I have no comment, would need to look at charts.

But if for a home workshop or similar, then you can just vary your depth of cut can't you? For example we have a 2 1/2" Seco in a 40 taper, 2 HP (I think) beefed up BP clone. Can be easily overloaded and stalled, but we are careful and use it for what it can do well - light cuts, moderate rpm, not trying to pretend we have a CNC....

ps added, we have had a good run from that Seco 220.13, it is positive/negative type, made for lower horsepower mills and ideal for mild steel, aluminium. You can use the extra positve inserts (razor sharp) and it will do plastic well, actually can use these same inserts for aluminium and mild steel.

1. At that RPM with a 2" cutter, your running 1250 SFM.

2. Chip load is 0.004" and Metal Removal rate is 10 in3/min @0.125" DOC.

3. Using a power constant of .2 (don't know alloy), you need about 2.75 hp at the cutter or about a 3.66 hp spindle motor to do what you're doing.

4. With a 3", 6 insert mill, your RPM should be 1,667 and feed rate would stay @ 40ipm with the same chip load. The metal removal rate jumps to 15 in3/min.

5. With the higher metal removal rate, cutter HP goes to 4.125 with spindle HP @ 5.5

You would have to change DOC down to about .1" to make it work.
JR

You would have to change DOC down to about .1" to make it work.

Click to expand...

Well, I guess what I'll gain in diameter I'll have to sacrifce in DOC. Thanks for doing my homework for me I'll bid on it...

appliedproto,

There are so many variants of face mill out there, just as important as size is the geometery. For example, I guess you wouldn't want a negative/negative cutter if most of your work is aluminium.
For example, Seco used to list around 10 different types of face cutter alone....

Ya, I was bidding on a new SECO Quattromill. Lost it though