I am currently doing microfluidics research and kind of stuck on this situation.
I am using a 0.79mm or 1/32 inch tool to mill a "bean" shape that is 1.2mm wide on a Polystyrene sheet.
However, my tool keeps breaking after milling one "bean" shape on a polystyrene sheet.
I used 7000rpm and 250 mm per min.
Can anyone of you give me a tip or method that I should take to successfully mill without breaking the tool?
The depth is 0.5mm, I did some research online and apparently I need a faster RPM, but my milling machine can only go up to 10200RPM
Can you recommend ideal RPM and feed rate ?
Ideal would be like a router. Maybe 25000 RPM.
You may be breaking the tool due to heat by going that slow and that low on rpm.
That is about 10 IPM, which is very slow for plastics.
Put some coolant on it and speed it up as fast as you can on RPM and I'd say at least 25 IPM. Maybe 50 IPM.
I suspect the 4 flute tool is your problem. Try a double as suggested or possibly even a single flute endmill (although at that size it may be very easy to break).
You can machine plastics with lower speed but the finish will suffer slightly, just keep your speeds and feeds relative - keep that tool moving and ejecting the hot shavings.