Dynamic Stainless

[cncClintain]

I just started a new job and we cut a lot of 316 stainless. We will be installing MasterCam X5 within a couple weeks. I have quite a bit of experience with MasterCam but not so much with the stainless. I was wondering if anyone had any general guidelines for the dynamic toolpath, mainly in regards to step over percentage vs. tool length. I was taught in school that 10 to 20 percent is standard but that was in school, real world results and fast cycle times are needed here. How hard do you push your cutters?

[metlshpr]

I use carbide inserted cutters and push them pretty hard. About 40% step over, small depths and high feed rates with a cold air gun seems to work for me.

[neurosis]

I use Dynamic for both conventional speeds and feeds AND high speed machining. If you are going to be using a high speed machining approach then 5 - 10% is a good place to start.

With your high speed machining approach you will be able to get away with much higher surface footage. I would call which ever tool mfg you plan on going with and ask what they recommend for their particular tool. I have been able to run up around 700 sfm with a 1/2" dia endmill as long as I keep my radial cut around 5%.

Also, if you plan on using a high speed approach dont forget to factor chip thinning in to the equation. If you are running a cutter that recommends a .0025 ipt, @ a 5% radial you will be able to calculate it to run a much higher chip load to get the recommended.

The nice thing about High speed machining techniques, is that you can use the entire length of the cutter rather than having to step down.

More specifics would be required from your end to be able to give you more specific information.

[cncClintain]

Originally Posted by neurosis I use Dynamic for both conventional speeds and feeds AND high speed machining. If you are going to be using a high speed machining approach then 5 - 10% is a good place to start. With your high speed machining approach you will be able to get away with much higher surface footage. I would call which ever tool mfg you plan on going with and ask what they recommend for their particular tool. I have been able to run up around 700 sfm with a 1/2" dia endmill as long as I keep my radial cut around 5%. Also, if you plan on using a high speed approach dont forget to factor chip thinning in to the equation. If you are running a cutter that recommends a .0025 ipt, @ a 5% radial you will be able to calculate it to run a much higher chip load to get the recommended. The nice thing about High speed machining techniques, is that you can use the entire length of the cutter rather than having to step down. More specifics would be required from your end to be able to give you more specific information.

Thanks. Right now they have been using inserted cutters for all of their roughing and they do decent size parts. I dont have a lot of experience with inserted cutters and Ive always been told that dynamic is faster and more efficient, mainly for the depth of cut and chip thinning as you mentioned. They do some pockets that require ''long" endmills and I wasn't sure how much to reduce my step over percentage to compensate for the extra length. All of their solid carbide is AccuPro. I guess Im going for the High Speed approach because Im mainly concerned with reducing cycle times.

[cncClintain]

Originally Posted by metlshpr I use carbide inserted cutters and push them pretty hard. About 40% step over, small depths and high feed rates with a cold air gun seems to work for me.

They have a lot of inserted cutters where I just started. What do you consider a small depth, I kinda thought about 3/4 of the insert would work but thats a considerable step over? Also, what kind of inserted cutters are you talking about? They've been using 2" what Ive always called a "shell" cutter (not sure if thats correct or not, only place Ive heard them called that was the first shop I worked at and it stuck) but what about the fact that theres such a large area of the cutter that does not cut, do you use a larger helix radius or a smaller entry angle when entering a pocket?

[cygnus x-1]

For calculating feeds and speeds I have found the GWizard calculator absolutely invaluable. There is always some experimentation involved with optimization but it gives better starting points than I would ever come up with, being fairly inexperienced still.

GWizard: A CNC Machinist's Calculator


No affiliation with CNCCookbook either, just a very satisfied user!


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