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Solidworks CAM, CAMWorks third impression
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| The part I am programming is some ballscrew flange I downloaded off the internet, I can't even remember where or what it is. I just wanted a solid model to play with the CAM package. I don't think you would use a 3-axis mill to make this part, more likely a turret lathe. Still, programming it give me a feel for how SolidWorks CAM operates, and the problems I will face in any CAM program. By the end of this 40-minute video, I had programmed a part that might break endmills, but in theory, at least it was carving out the part with the proper features. Best yet, I did this with only two endmills, a 3/8" and a 1/8" carbide 2-flute tools I bought from Avid when I bought the CNC mill. While rehearsing for this video, I messed and messed with the program. In some of my practice runs, I eliminate any roughing, since Destiny tool sells Viper endmills they claim you can use for both rough and finish milling. I also changed the operations from plunging the endmill down, to spiraling down. There were several places, like the 1/4" holes where I ended up with gouged material. I fixed this by eliminating lead-ins, which did not seem to be needed when the tool spirals into the stock. By the time I was done, the machine time was under nine minutes. I suspect I would break tools if I ran this fast, but the benefit of a high-speed spindle is that it lets you do high-speed machining. As long as the harmonics of the cutting action do not generate tool chatter, it is fine to cut aluminum at 24,000 RPM. You do need coolant so the aluminum does not stick to the tool flutes. I will be using Trico MD-7 in their micro-drop unit. |
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| Many forum posts state that spindle torque is "more important" than spindle horsepower. They are both important. For a constant-torque spindle like I have, it has the same turning force at 8,000 and at 24,000 RPM. It is a 2.2kW spindle, equal to 3 HP in English units. The torque is an absolute necessity for carving a sharp edge though the aluminum. The amount of torque is based on how deep the cut is, and whether you are cutting a slot, or just taking down an edge. The horsepower of your spindle will determine how many of those cuts you can make in a given time. So you should always start by thinking of the spindle running a full speed, at least for a constant-torque motor. If I run my 3HP spindle at 12,000 RPM it is a 1.5HP spindle. If I run it at the minimum, it is a 1HP spindle. Now with 24,000 RPM in your mind, think of all the things that make that unusable. If the tool is a large diameter, the tips of the flutes may well exceed the maximum SFM of the cutting operation. I keep 1000 SFM in my head for aluminum, so that is a good place to start. This is why I run the 3/8 tool at 12,000 RPM and the 1/8" tool at 24,000 RPM. Now this is all predicated on taking a deep enough cut, but not too deep, by setting the feedrate. Too thin a chip and you overheat the tool. Too thick and it overheats and maybe breaks. Once you get the right-sized chip as far a feedrate, you can figure a depth of cut (DOC) that does not exceed your spindle torque. Since my beloved Panasonic GH4 did not focus correctly, I did not appear full-screen in this video, but the small display I do use is big enough for you to see what I am talking about. |
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