[AP71]

I am trying to figure out the most cost effective way to slot 304 ss.

Here is the setup: I need to make a 1.71 wide slot that is .300 deep and is 1.00 inches long.

I am looking the fastest and cheapest (dreaming, i know) way to make this. Corners in radius are fine.

I would love to hear what some of you Pros would do. Right now I am using trochoidal milling with 7/16 endmill 4 flute carbide around 4500rpm and .030 stepover at 80ipm. It is working but tool life is not what I was hoping for. Indexable or solid tooling?

I should probably add that I am running this on a Haas DT-1

any help is greatly appreciated.

Thanks!
Angelo

[hoffmannm]

What are you using to program? Does it have the capability to output the correct high feed tool path for you? 80ipm is getting up in the high range, and even though you have a very very low step around 6%, you still will get high radial engagement in the corners, unless the program can properly output this, you maybe never get good tool life.

your current settings equal out to be .0044 IPT and 590 SFM I believe. I am no pro but maybe try lowering your IPT too .0015 or 27 IPM and increase your step over to a starting point of 15%.

[hoffmannm]

also check out this site if you haven't before

Trochoidal Milling Feeds and Speeds - CNCCookbook CNCCookbook

he provides a pretty solid and in depth Speed/Feeds calculator with things like High Feed milling in mind.

[bluechip9]

I have spent a great deal of my 30+ years machining all grades of stainless steel. I will never claim to be an expert but... I have tried many different cutting tools and methods over the years. Many of which were claimed by tooling salesmen to be the best out there.
Although there may be those who balk at my advise to you, I have found high speed steel cutters to work the best and last the longest in stainless. You may think they are too slow but, given the much greater depth of cut you can take with them, they can still be an efficient means of removing stainless.
I'm not familiar with the hp and rigidity of a DT-1 but as an example, we still have an old Tree 425 cnc knee mill. On this machine I would easily cut the slot to full depth in one pass with a GOOD QUALITY high speed steel rougher (3/4" diameter) with the first pass being the full diameter cutting width at 50sfpm (about 250 rpm) and .002 ipt too start. This would equate to 2 ipm. May seem slow but, you are removing a great deal of material at once. If a good finish is required, you can the follow up with a light finish cut at much higher speeds and feeds with carbide.
There is still a place in this modern world for hss.

[jdoub55]

I agree with Bluchip...a 1" high speed hog em would probably be your best bet....climb mill rough with in .01 and then finish with your carb High feed tool.
Keep heat to a minimum. The difference between 303 and 304 stainless is almost night and day as far as machining. Just what I have found .