Need help calculating cutting forces for CNC Routing

Hello, Please I need help calculating the cutting forces in routing operations. I need it for my final year project, which is the Design and Fabrication of a Modular CNC Machine tool.

I would start by finding the torque that your spindle will produce. This will be the maximum cutting force that your machine will see. If you are running 12mm with a 5.6KW spindle @ 24000 RPM the cutting force at maximum cut is pretty strait forward. I am sure guys around here with more experience then I could correct if I am wrong but it makes sense as to the maximum load that the machine would put on the cutter. for example .5" 7hp spindle at 24000 RPM would have 1.53 ft/lbs of torque. That translates to 73.4lbs of cutting force on the cutter. how big of motor you put on the machine is a matter of engineering economics.

Hi Imp - Ray above has done a calc and that is one method. If you do a search for cutting forces on tools calculator there are a few. But even if you know the forces this is nearly irrelevant to the required stiffness of the machine for its cutting duty. You will need to look up "chip load". This is the size of the chip of the material that is being removed as the tool progresses. There are two forces involved, 1) as ray has calculated which is the rotational forces involved in creating a chip plus B) the translational force to push the tool forward. However if the machine deflects then the tool either skips (result=chatter) or slips (result=friction and rapid tool wear). So even though you may figure these out they don't help with the machine design. So depending on what you want to cut depends on how stiff the tool needs to be. You say CNC machine tool, is it a lathe, mill or router? If a mill or router and you want to cut aluminium effectively then you will need a tool stiffness of at least 20N/0.001mm. Modern VMC's are in the order of 100-150N/0.001mm plus. There are machines quoted at greater then 700N/um... Small tabletop mills can be as low as 2N/um static stiffness but this is at the wobble end.... Peter

so tell us what you need the machine to do and more detail can follow...

https://www.kennametal.com/us/en/res...ng-forces.html