Fusion 360 Feeds and Speeds
Feeds and speeds can be a complicated problem due to the many variables ranging from the material being cut, machine rigitidty, spindle horsepower and torque at different RPM, tool material, to name a few. In general, we have some guidelines that help us achieve, optimal feeds, and speeds on the axyzmachines mx3. There is a plethora of guides and calculators online that can be challenging to understand when trying to figure out the feeds and speeds to for milling or drilling. The simplest calculator I have come across is from our friends over at littlemachineshop.com It is very straightforward and easy to understand.You only need to know the the following parameters .
Unit of Measure
Operation
Cutter Material
End Mill Diameter
Spindle Speed
Cutting Edges
For example, if we wish to calculate the feeds and speeds of 6.35mm (1/4) endmill, it would be as followed
Unit of Measure: mm
Operation: milling
Cutter Material: carbide
End Mill Diameter: 6.35 (¼ inch)
Spindle Speed: 3000 RPM
Cutting Edges: 3
The calculator by default will preset the cutting speed and I recommend leaving it as it is.
The calculator should compute the following parameters.
Chip Load: .051 mm/flute
Feed Rate: 457mm/min
We can then take these two parameters and plug them into fusion 360 and it should look something like the image below
Note that you only need to input the RPM and The Feed Rate, fusion will automatically calculate the surface speed, feed per tooth and feed per revolution
We notice that fusion 360 will calculate the feed per tooth or chip load (little machine shop calculator) of .0507mm which is comparable to that from the speeds and feeds calculator .051mm.
For the lead-in/out feed rate I generally keep it 100mm below the cutting rate, this is also dependant on the depth of cut and step over. If you are taking a 30mm depth of cut and a 1.27mm stepover on a 6.35mm end mill you might want to slow down your lead in speed by 70 percent of your feed rate. Slowing down the lead-in will ensure that the cutting tool does not flex and break due to the force generated when leading into a cutting move onto the material.
For the ramp feed rate, I also keep it 100mm below the cutting feed rate while maintaining the same rpms of the spindle speed.
When milling keep the plunge feed rate 150mm below that of the cutting feed rate, this will ensure that you do not clog the flutes and break the tool bit from plummeting too fast into the material being cut.
Two other important parameters to keep in consideration when milling was briefly stated above, stepover and depth of cut.
Stepover is how far from the previous cut the next cut occurs. A cut it made, the bit is "stepped over", and the next cut is made. If the Stepover is 0.08 mm, then you are cutting 0.08 mm of new material. If your stepover is 1.5, you are cutting 1.5 mm of new material. It increases the "resolution" as you are taking a smaller cut. When starting out, take 20 percent of the diameter of the cutting tool. So a 6.35mm endmill would be as followed 6.35 x .20 = 1.27mm step over. The stepover will largely be impacted by the depth of the cut. taking too larger of a step over on a deep cut can damage or prematurely wear out your bit.
Similarly, a depth of cut is how deep your cutting tool plunges into the material to cut.
Optimal load refers to the step over and multiple depths refer to the depth of cut. In the image above 23 percent of the 6.35mm end mill was taken