Maximum Depth of Cuts

[Jim S]

Indiefan

If you are having still having trouble it may be because there are many factors that go into a good part setup. First you said you are using a four flute end mill, this is not the preferred tool for your material, and a two or three flute would work much better in that it would not tend to clog up as quickly.
Coolant is also important when cutting aluminum, along with what type of cutting you are doing such climb milling, conventional milling ,pocketing or channel cutting .The type of machine you use will also affect your results. Are you using a cnc mill? , a standard mill?, or a bench top mill ,each of these machine have different spindle speeds and rigidity .
I am sorry for not answering you question with a number (ie cut .125 deep) but as you can see there is no simple answer. I would be happy to help you with making what ever you are making .I can sent you a cutter and a nice little slide card that make calculating speeds and feeds much easier.
Let me know how it woks out and if you need some help. Your friend on team 107.


Jim Schaddelee
Team 107 mentor

[Veselin Kolev]

I agree fully with Jim. There is no simple answer to your question, and as he says, a 2 flute cutter would be better for the job.

A two flute will cut more material per flute than a 4 flute, however since you are cutting aluminum, the more material cut will not matter too much to the cutter. I have rarely broken a cutter on aluminum (once if I recall correctly...). As long as you keep the spindle speed and the feed rate right, as well as use proper cooling, the cutter should be fine on even heavy cuts. Also since there are only 2 flutes, there is more of a relief groove on the cutter, so the chips fly out easier, preventing blockage.

Remember, different materials have totally different cut techniques. For example, I would always cut steel with a 4 flute cutter.

As for the original question, it is hard to say with the info you have given us. If you have a mill that is similar to a Bridgeport Series 1 mill, and in decent condition, you are in good shape to do heavy cuts. If you are running a half inch cutter, 2 flute, HSS, you can probably get away with cutting .250" deep with a 3in/min feedrate. That is, if you keep it constantly cooled. If CNC, you can mostly only judge by the sound of the cutting and the heat produced. If non-CNC, you can usually just go by the seat of your pants and judge the feedrate by the feel you get through the screws.

The main issue with cutting deep is that the part you are cutting has more of a tendancy to be sucked up into the cutter. If you have a part viced down very well, you can cut normally. But if you have a wierd part that isn't held on too well, be very careful. Take cuts as small as .050" per pass, or lower the feedrate, depending on which direction the part is more prone to slip.

The art of feedrates and cutting depths is hard to perfect, it takes many years to learn, and can't be easily explained. The more experiance you have on a mill, the better. Hope that helps.

~Veselin Kolev

[Rod]

Start light on the cut and low on the feed rate. If you have a CNC Mill go with the defaults in the CNC program. The nature of what we mill for robotics allows us to go a little slower than a full production shop. So it takes 10 minutes per part longer to go slow, we are only making 2 parts not 10,000. Take your time, enjoy what you are doing and remember the lowest feed rate on a mill still beats a file.

[Jason Kixmiller]

It's also important to remember that the tool will cut best at different speeds depending upon direction. In other words, drawing the piece towards you along the end mill and then drawing the piece away from you will cut differently even if the depths are the exact same. Good luck!