Is stainless steel

[CNCadmin]

considered hard ? How would I go about machining it on a lathe?
What type of cutters, lube etc??

[Rekd]

It's about midle of the road in hardness, some exotics are hard to stainless like stainless is to alum. There's also different grades/hardness' of stainless. As well as some "free machining" stainless.

For turning, mostly coated carbide inserts. Most water based coolants will work. Tapping may require tapping oil on smaller holes.

It's a little intimidating at first, but when you've ran it a while it's actually nice to machine.

'Rekd

[Jennifer]

A little info on stainless steel...

http://its.foxvalley.tec.wi.us/MachS.../turnsteel.htm

[cadman]

Austenitec stainless steels (300 series) are generally tough and gummy. Work hardens easy. Martensitic stainless steels (400 series) are harder, but the higher carbon to chromium ratio makes them more free machining. Precipitation hardened stainless (17-4, 15-5) are almost always machined in an annealed state, and machines like 300 series but is somewhat tougher. Also work hardens.
I mill a lot of 316/316L, 304, and some 302, 15-5, & 400 series.
I don't do much lathe work but machining is the same turning or milling. Stainless with high chromium content (300, ph) require slow speeds & high feeds. The tool needs to cut under the hardened layer. Stainless is also a poor heat conductor, so the heat generated during the cut will tend to remain at the cutting edge of the tool rather than be carried away with the chip. Flood coolant is generally the only way to keep the tool from burning up. Some shops are successful with dry machining. When milling I use pm roughers for hogging and carbide endmills for finishing. For turning I use carbide inserts for roughing & finishing.
For your specific machining needs just look the Machinery's Handbook or any machining reference book and you'll find everything you need to know.
Hope this helps.

[CNCadmin]

I have a piece of SS how can I tell what type it is?

[HuFlungDung]

Originally posted by CNCadmin I have a piece of SS how can I tell what type it is?

I lick it to determine what it is from what it tastes like

You can distinguish to a certain extent with a magnet. Type 304 and 316 are nonmagnetic, type 416 is weakly magnetic.

[Rekd]

Originally posted by HuFlungDung I lick it to determine what it is from what it tastes like

/me wonders where Paul had that piece of stainless..

'Rekd teh Vivid Imagination

[CAMmando]

Precipitation hardened stainless (17-4, 15-5) are almost always machined in an annealed state,

Just my $.02

I turn all PH stainless in heat treated condition up to about 180 KSI tensile. Then I decide on a job by job basis depending on the geometry and tolerance involved. Up to 180 KSI, PH's cut very nicely. In some cases BETTER than in annealed condition using coated carbde inserts.

[hardmill]

Originally posted by Rekd /me wonders where Paul had that piece of stainless.. 'Rekd teh Vivid Imagination

Thanks for the visual 'rekd as a result i'm now blind.

PEACE

[M@T]

I turn a lot of F316/316L/F51 stainless and actually prefer it to normal steel such as A10 and the dreaded stringy horrible steel that is LF2.

Slower surface speeds are required though. I use 2.5mm cuts per side with a CSS of 80-100 with a feed of F0.3 per rev as opposed to CSS 200-250 with normal steel.

Stainless isn't really that stringy and you can get a really nice finish with it fairly easily.

It also takes longer to machine which gives me more time to sit down and do sod all while the machine is running

[M@T]

You will need proper stainless tips though. I use DNMG 2035 for stainless and DNMG 4025 for normal steel. Not sure what the difference is but it does the trick

[M@T]

Had a new type of stainless (new to my work, not new to everyone) come in this week called F44. ****ing evil stuff. I cut 316 at 2.5mm per side, CSS 80 and F0.3 but this crap would only just about take 1mm per side, CSS 50 and F0.2.

Even then I was having to change the tip after each component. Blew several tips up trying to find the right cut. The steel turned bright red and peeled back instead of chipping.

I have 2 almost identical jobs, the only difference is one is normal steel and the other is this F44. The steel takes 5 Min's to machine and the F44 took 56 Min's.

No more of that thanks