Relationship between speed and feed calc. and optimal load in the manufacturing tab

[greggor.mcgrath]

Hello all, I have a rookie question about  my speeds/feeds calculator, Please keep in mind I have only had my CNC machine for about 13 months and been making chips for roughly 10 months. I have been running a lot of my parts at low rpm with low feed rates with great results however I want to learn how to speed things up as I have a job coming up where time is a factor. I am using a speed and feed calculator that is giving me a feed rate of 48 in/per at aprox. 8k spindle speed on a .250 3 flute with a 'radial' of .013 at full depth/axial of .350

Here is the confusing part for me, Fusion defaults to .1 radial under optimal load however if I input .013 as the speed and feed calculator recommends I obviously get and insanely long tool path due to the small step over. Now as fusion describes, Adaptive HSM varies so that the tool does not over load. Do I leave the default Fusion gives me based on the tool diameter or?

I have had success using the calculator with micro "2 flute" tooling however with the larger tooling the stepover/radial from my calculator vs optimal load in fusion on 3-5 flute end mills are just not jiving due to my inexperience.

Thank you so much in advance for any help possible in explaining/clarifying things for me 🙂 

[fr33l0ad3r]

Hi. When defining your best speeds and feeds count on several things other than Fusion default:
Spindle capacity - how much torque it can give. S1 and S6 modes sometimes rated even for cheaper motors/electrospindles. And for S6 you can use trochoidal milling - that's cool!

Axes capacity - how much force it takes to push spindle around. Can your drives handle high dynamics w/out missing steps or, for servos before they stall?
The relationship between feed and cutting width is inverse. Example from vendor catalogue:

ae is for cutting width. See how allowed feedrate increases with shallower passes. For common, you can go with 40 to 60% dia load if you want smaller program, but that's for metals - softer materials allow full width cut for a regular, sharp end mill.
If your machine does not like dynamic milling when so many lines of code are fed to it - go for conventional pocket/3d pocket milling.

[greggor.mcgrath]

@fr33l0ad3r Hello and thank you for the info. I do have an 11hp spindle capable of 10k rpm. I think the most confusing part for me is the optimal load tab under passes in fusion. I would like a better understanding on that and it's relationship to radial stepover in a speed and feed calculator. Thanks again for the previous info!

[fr33l0ad3r · Accepted solution]

Radial stepover, width of cut, optimal load all refer to the same thing.