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Stupid question from someone who hasn't run any stainless but why not run at the full 3500 RPM and a feed rate much higher like 14-17 IPM?
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I had to machine stainless for the first time tonight. Don't plan on doing it again in the near future, but my question translates to mild steels also. I have a 3500 spindle right now but am changing it to the 6k soon.
I used a 5/16" 4 flute carbine endmill. I used a DOC of .05", spindle speed of 2333 and cut at only 2ipm. I was cutting a rounded square in the top of a 1.25" rod. So it wasn't full cuts at all. The problem is that the motor seemed to "bog" down sometimes and seemed to have no power. Now I know that I have to expect this, but at one point the machine spiked the power and turned the computer off! Now I am really afraid that when I change over to the 6k spindle I will be screwed!
What do people do when they have to machine something at a much slower spindle speed? Help!
-Keith
Stupid question from someone who hasn't run any stainless but why not run at the full 3500 RPM and a feed rate much higher like 14-17 IPM?
Your doc is too small, spindle speed to high, feed to low, that would be my guess. Running high rpm with low feed rate will wear the edge right off your cutter - now your trying to push the material off as opposed to cutting it. It's hard to come up with answers in a forum like this when you can't hear or see what's going on with your operation. But with S.S. I've found - you can't rush it.
The thing is that if I slow my spindle speed down any more I feel like it is not going to have enough power to even keep the spindle spinning. It already feels like I am driving 20 miles an hour in 4th gear if you can get what I mean...Originally Posted by MikeZee
I plugged your numbers into the GWizard calculator, and got a recommended feed of 12IPM. For a 3500RPM spindle it calls for 17.5IPM.
Sorry to say it but you could be helixed.Machining stainless creates conflicting requirements: Stainless needs a low SFM even with carbide cutters and running a spindle at a low speed severely reduces the available torque. However, stainless work hardens under the cutter so you have to make sure the feed per tooth is adequate to get under the work hardened surface, this means the feed has to be fairly aggressive which needs plenty of torque from the motor. Also the work hardening means the radial depth of cut has to be deep enough to get under the work hardening so again good torque is required.
You can try to work around the problem by taking many cuts at a very small axial depth of cut so the chip area is small which minimizes the torque needed, but then the tip of the cutter is doing all the work and it will dull quickly.
An open mind is a virtue...so long as all the common sense has not leaked out.
AND....
you ARE running a VERY heavy dose of fluid coolant......right?
The RPM you are using is good but feed should be 12IPM
www.integratedmechanical.ca
Yeah I had the coolant full on...
12ipm seems crazy to me... but I will give it a shot...
I have found that these hobbyist type machines work totally different then we expect sometimes.
Give it a shot and let us know what happens.
http://www.cnczone.com/forums/chinese_machines/128856-my_j-cut_nightmare_machine_one.html#post944750
Consider swapping the toothed pulleys on your spindle drive with another set with a, say, 2:1 ratio (or whatever will physically fit). Double the torque. I haven't tried different pulleys myself, but it looks like it'd be straightforward.
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