316 Stainless steel cutting

[Jonathan Coates]

I decided over Christmas that I would make a replacement clip for my coffee machine and found a piece of 316L sheet that would do. The clip is like a washer but has three tabs on the inside and it slips on, sort of bayonet fashion, to secure the filter in the handle of the espresso machine.
Back to the plan.
I decided to chop off a square from the 2mm sheet as a starting point. I thought I'd drill an 8mm hole and hold it by a nut and bolt which would then go in the collet chuck. The pilot drill went through, with a lot of screeching but the 8mm drill now looks like a counterbore cutter. It definitely didn't want to cut any longer.
Never mind, I'll use an end mill in the mill. Now I need a new 8mm end mill as well.
Is there a way to get rid of work hardening in this devilish stuff?

BTW the 304 worked better, but had it's moments too.

 

[GreenTwin]

I discovered that feature when welding stainless beer keg sheet to make a furnace outer jacket.

I recall someone mentioning how they handled it, but I can't recall if they said drill very fast and hard (edit: or slow), or use a lot of cutting oil, or both (I forget exactly).

I ended up welding most of the shell.

And for a rough hole, you can turn the welder up a few settings too high, and burn through it with a stick welder.

The beer keg was very springy, and you have to use caution when slicing one, since they spring open somewhat violently.

The only thing I will use stainless for is some object that must remain outdoors at all times.

.

 

[mcostello]

Stainless steel needs a slower speed and a heavier feed to keep from work hardening the metal ahead of the cutting edge.

 

[Jonathan Coates]

It seems like drilling a pilot hole hardens the periphery of the hole sufficiently to make it unworkable from there on in. I've only ever messed with this stuff using a plasma cutter and tig welding for fabrications. Machining is a thing to be avoided at all costs I think.

 

[ranger]

I’ve found for drilling or tapping hard materials, Swarfega hand cleaner or E45 skin cream works very well as a cutting lubricant. This with a slow speed and maintain pressure.

 

[bluejets]

Is there a way to get rid of work hardening in this devilish stuff?

No, you've done your dash...next time , sharp tools and SLOOOOWLY with pressure.

 

[SmithDoor]

I decided over Christmas that I would make a replacement clip for my coffee machine and found a piece of 316L sheet that would do. The clip is like a washer but has three tabs on the inside and it slips on, sort of bayonet fashion, to secure the filter in the handle of the espresso machine.
Back to the plan.
I decided to chop off a square from the 2mm sheet as a starting point. I thought I'd drill an 8mm hole and hold it by a nut and bolt which would then go in the collet chuck. The pilot drill went through, with a lot of screeching but the 8mm drill now looks like a counterbore cutter. It definitely didn't want to cut any longer.
Never mind, I'll use an end mill in the mill. Now I need a new 8mm end mill as well.
Is there a way to get rid of work hardening in this devilish stuff?

BTW the 304 worked better, but had it's moments too.

Most 3xx stainless is easy.
Sharp tool bit and lost of coolant.

If you try 4xx stainless steel it is magenta . The have very shap tool bits and use oil is best most lathes have just coolant. Low speed also helps
Never let the tool bit get dull or will have problems aka glass hard.

Most machinist have a magnict in there tool box for testing between 3xx and 4xx

Dave

 

[timo_gross]

Stainless steel needs a slower speed and a heavier feed to keep from work hardening the metal ahead of the cutting edge.

I have not much experience with "that stuff" (304). Machining it with a carbide end mill works surprisingly unspectacular, if I do not try to deviate from "the given recipies". Coolant is a must, rpm must be lowish, feed rate must deliver the required chip load.
Drills HSSCo for Stainless have a thiner webb, splitt point, to avoid rubbing, maybe even higher relief angle?



I am reasonably sure that this strategy also works for stainless steel.

On the lathe I drilled some bushings in 304 and had to use a fresh drill for every workpiece (all the cutting parameters wrong, I just used several drills and sharpened them after finishing. Today I bought some carbide drills.

 

[Richard Hed]

Most 3xx stainless is easy.
Sharp tool bit and lost of coolant.

If you try 4xx stainless steel it is magenta . The have very shap tool bits and use oil is best most lathes have just coolant. Low speed also helps
Never let the tool bit get dull or will have problems aka glass hard.

Most machinist have a magnict in there tool box for testing between 3xx and 4xx

Dave

So which one is the magnetic?

 

[SmithDoor]

So which one is the magnetic?

4XX is magnetic and can be a bad day for the machinist.

Dave

 

[L98fiero]

I am reasonably sure that this strategy also works for stainless steel.

On the lathe I drilled some bushings in 304 and had to use a fresh drill for every workpiece (all the cutting parameters wrong, I just used several drills and sharpened them after finishing. Today I bought some carbide drills.

There is a feed/speed calculator, GWizard that is free for hobby size machines, it takes a bit of learning to get the right speeds and feeds for your particular machines but overall, it will get you in the ballpark right away. One of the first settings is conservative/aggressive slider, just trying it with stainless shows that if you are too conservative in feed rates, the tool deflection increases resulting in a dulled or broken cutter.

 

[Mike Henry]

HSMAdvisor is another feed & speed calculator that is available and I find it much easier to use and more reliable than GWizard. It also has a mobile version (FSAdvisor) which is handy at the machine if there is no computer nearby.

https://hsmadvisor.com/

 

[L98fiero]

HSMAdvisor is another feed & speed calculator that is available and I find it much easier to use and more reliable than GWizard. It also has a mobile version (FSAdvisor) which is handy at the machine if there is no computer nearby.

https://hsmadvisor.com/

I have both GWizard and HSMAdvisor and they are not related other than they have speeds and feeds calculators and engineering information like weights calculators and tap drill size charts, etc., each has it's strong points.

 

[bdrmachine]

4XX is magnetic and can be a bad day for the machinist.

Dave

I have machined tons of 416 SS. Easy to work with and not as prone to work harden as 300 series SS. If you get in trouble with SS you can try and grind the surface hardened area to expose fresh metal.

 

[Richard Hed]

I have machined tons of 416 SS. Easy to work with and not as prone to work harden as 300 series SS. If you get in trouble with SS you can try and grind the surface hardened area to expose fresh metal.

I've got this stuff that came from agricultural usage. I'm sure it's stainless as it looks like SS and it does not rust. It is magnetic and it machines very well. The chips are like stainless.

 

[L98fiero]

I've got this stuff that came from agricultural usage. I'm sure it's stainless as it looks like SS and it does not rust. It is magnetic and it machines very well. The chips are like stainless.

Agricultural usage is a pretty broad description, do you know roughly what he part is or what it's from?

 

[roncohudd]

I've got this stuff that came from agricultural usage. I'm sure it's stainless as it looks like SS and it does not rust. It is magnetic and it machines very well. The chips are like stainless.

Maybe 17-4

 

[Richard Hed]

Agricultural usage is a pretty broad description, do you know roughly what he part is or what it's from?

Yes, the pieces are from long rounds about 1-1/2" to 3" used for some kind of water pumps.

 

[L98fiero]

Yes, the pieces are from long rounds about 1-1/2" to 3" used for some kind of water pumps.

Just a guess, but from the application it's likely 304 stainless.

 

[ajoeiam]

Maybe 17-4

Dunno about it being 17-4 - - - that stuff is real tough working material.
As the stuff is magnetic - - - maybe a 400 series? (If I'm remembering things from the machinery's handbook at all.)