Machining 304 Stainless Steel: Feeds & Speeds WW167

Let's experiment with Feeds & Speeds to CNC Machine 304 Stainless Steel, including outside profiles, internal pockets and drilling 304 Stainless!

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[RallyRat]

What really drove home how careful one needs to be with 304 is the realization that its yield strength is similar to hard aluminum or a low strength steel, but after factoring in in tensile necking its ultimate (work hardened) strength is similar to the strongest steels! Thanks for the vid!

[jnelson]

It's kind of fun seeing other people learn about stainless - my first job was at Greyhound, and those things were almost all stainless. Body panels, frame members, interior components, got real used to being careful around edges. Abrasives work very well with stainless as well - we normally used cutoff wheels for working with sheet metal. Cheap ones would almost evaporate though in the face of the metal - the body shop manager groused about the cost of good cutoff wheels until he saw how many cheap ones we went through :)

For me, regular steel in my home shop has been a revelation. 12L14 steel? Holy crap, what a dream compared to fighting stainless...

[hdfanboy]

Great video as usual and thanks so much for adding the metric calculations which is super useful for us Australians. Also your new microscope is an awesome addition to your shop it is really cool seeing the swarf up close.

[tysonlamb]

Great video J! I'm sure a ton of guys will benefit from this. Always use 303 instead of 304 if you can. Glad I could help.

[chasenichole]

Finally someone who has an informative video on this topic! Thank you!!

[andrewgiles]

thank you so much for adding mm alternatives. the way they just appeared on screen as you were speaking was my favourite, as it doesn't take up video time for your US audience, but everyone in Europe can glance and know what you're​ talking about. throwing them on screen during editing is hopefully quick and easy. I'd love to see it continue please

[Zappyguy]

Cobalt drill bit.
Rubbed a bit on a part, and this little factoid saved the project! Thank you again for all your work!

[Yamaprilia]

A couple of points on this subject.
Firstly you say not to whisper cut but I work on some bigger jobs that have 0.05mm tollerance on some of the dimensions, you cannot achieve this with a high step over as you get cutter deflection, especially when the tool is long.
I have 50mm 304 plate to machine and I have found a way to do the whisper cuts by using 6 flute cutters and by going very slow with the feed and speed and doing 2 or 3 clean up passes. But this takes alot of time obviously.
Secondly I am working with haas and ycm machines, they do not offer enough coolant pressure to evacuate chips, alot of people will be in the same boat as me. This means constantly stopping the program to remove chips.
You can get air attachments but you need a boss thats willing to buy and install these attachments, of which I do not have! So I recomment breaking up your program into smaller parts so its easier to get to position where you can stop the program to remove the chip buildup.

[shapezula]

We had some stainless steel pipe at work we were trying to hand drill and we mixed water with baking soda to apply on the bit and it helped tremendously

[MrReardan]

The failure attempt looked exactly like mine with the carbide end mill getting orange. Thanks for all the detailed speed / feed settings and tooling information!

[Regalmetalworks]

Yup, I had the same experience as you, melted the 6 flute lsc and gave up. But then I decided to try a rougher and had great results. This is great John! I am putting this in my tool library right away!

[OldIronRC]

Really enjoying the improvements to the videos with the inlays of the software windows. Great stuff John!

[oneworks]

Ahhh this would have been so handy a couple of months ago, with metric even! Still learnt a lot from it, machining is definitely one of those "the more you know, the more you realise you don't know" things. One thing my Sandvik rep mentioned that you didn't (you may have heard otherwise?), if you end up going to a carbide drill, don't spot it. The carbide drill should be rigid enough and spot drilling risks chipping the more brittle drill. This video also goes nicely back to your "Twist Drills are AWESOME!" video, because of the shallow ramp angle, drilling a start hole is going to be quite a bit quicker in a lot of cases.

[Wrenchmonkey]

Can't wait to try this. Pervious attempts have trashed a lot of endmills for me...

[frankmuller]

;) Perfect! Thank you for sharing those hints and tricks... awesome video... you even included some metric measurements... thank you for that... your visits to Germany finally seem to pay off! ;) Joking of course... you are great... take care!

[GeofDumas]

Great info! I have always noticed more resistance with ramping in titanium with 5 flutes but I had never given it a second thought since I do so little ramping

[chrispalombo]

I wish I had seen this last week, before 4 hours of stainless steel nightmare.

Ate up all kinds of HSS and Cobalt!

[madaxe]

I just found this video after breaking a couple of endmills machining some 304, I've turned heaps of 304 before, but never milled it, This video was helpful, but I found that I had to increase the spindle speed by around 30%, and decrease the feed by around 15% before I could get good cuts and good tool life. this did get me started though.

[antsman]

I absolutely love machining 304 and 317. When you get the right speeds and feeds you'll get such a beautiful finish, but it will also let you know when your wrong. About 60% of what our shop machines is stainless and I honestly don't know why everyone thinks stainless is so difficult to machine. I would much rather machine 304 then tungston or tantalum, or even some plastics like rexolite or velspel.

Ease in to the material and keep it moving. I use 240-400sfm as my range for milling 35-45sfm for drilling with colbalt. Carbide tsc drills are even more fun and faster! Ever since high-speed dynamic milling was introduced, that's 90% of what I use. Some times I'll go up to 500sfm when roughing.

I also form tap all my threads in stainless, unless called out for cut or thin walled, from 000-120 to 1/2-13. And the 1/2-13 went 1.125 deep no problem.

[stefanhertweck]

John, great information. Thanks for sharing your tips on how to mill/drill stainless steel.