[mflux_gamblej]

I'd like to take a moment to complain about stainless steel.

1.) do Not order your SS shear cut, pay extra for plasma, laser, or waterjet cut. You'll lose 2 hours, and a good 1/8" (at least) to milling it flat

2.) if it screeches while cutting, you've work hardened the SS, and need to increase spindle speed, decrease the chip load and maybe decrease the feed rate. listen for buzzing like a bee hive - that's a happy endmill in 304 SS

3.) did I mention not ordering shear cut?

4.) screeching will happen.

f***!!

[mflux_gamblej]

This is on my Interact 1 mk 2 (~ 10 HP)

I found that for a 1/2" endmill, around 2400 RPM, 120 IPM and around 0.25" wide by around 200 thou deep works OK.

Until you run into a thicker area in your sh*tty shear cut SS, that is.

my project is due soon, having to re-order the SS plasma cut, costing me around $100 and 3 - 5 days.

The new steel had better be flat.

[SirDenisNayland]

120ipm?! That's a good way to chew through an endmill per piece.

In my experience 304 in most any form other than a cold finish and you'll have to cut through scaling and the likes which are always a lot harder.

Regardless, 304 is a *****, and quite personally i would never rely on any material to have a truly flat surface which you won't have to finish for the part.. brass, mild steels, aluminum.. doesn't matter, its not gonna be truly flat from the mill.

Oh, and have you considered a regular old sawcut? I can't say for certain but I can see other methods you mentioned imparting more work hardening than a regular old saw..

Cheers

[mflux_gamblej]

A bandsaw cut would be just great. I've been ordering from discountsteel.com they do not offer saw cut for 304 SS plate.

I started out with a 3" face mill, low spindle speed, low feed rate - went horribly, probably f*ed up my inserts.

I switched to a stubby 0.5" endmill. If you keep that 'bumble bee' cutting sound, it seems happy. The endmill looks to be in good shape, and the finish i got is pretty good.

I found out that my spindle is overspeed tonight, so my speed of 2400, is actually over 4000 RPM.

but the 120 IPM was between 117 and 123 IPM when the endmill was happiest. This is under weak coolant flood flow (trying to avoid a major coolant mess from my non-enclosed mill)

I definately had to cut through the scaling as you say.

Regardless.. damn 304 SS. I've got to machine two fairly large pieces by end of week next week. Any pointers and best practices would be appreciated.

120ipm?! That's a good way to chew through an endmill per piece.

In my experience 304 in most any form other than a cold finish and you'll have to cut through scaling and the likes which are always a lot harder.

Regardless, 304 is a *****, and quite personally i would never rely on any material to have a truly flat surface which you won't have to finish for the part.. brass, mild steels, aluminum.. doesn't matter, its not gonna be truly flat from the mill.

Oh, and have you considered a regular old sawcut? I can't say for certain but I can see other methods you mentioned imparting more work hardening than a regular old saw..

Cheers

[gridley51]

The quickest way to workharden anything is to increase spindle speed and decrease feed.

[UUU]

A linked thought. Why is 303 so hard to get in flat bar? Round - yes, square - maybe, but as soon as you want rectangular bar you almost always have to get 304.

[gridley51]

A linked thought. Why is 303 so hard to get in flat bar? Round - yes, square - maybe, but as soon as you want rectangular bar you almost always have to get 304.

Because 303 is the free machining version of 304 and round is where the demand and therefore volume is.
I only buy 304 when stainless is specced because it is cheaper and I can`t remember any jobs where we had problems machining it.
Obviously if the customer specs a grade,he will get that grade but lots of jobs just say stainless.

[SirDenisNayland]

I only buy 304 when stainless is specced because it is cheaper

Man I would hate to be an employee of yours. What you just said is the complete opposite of what every machinist has believed since the dawn of 304 stainless.

Also I doubt its any cheaper. I cut through 303 all day long like its butter, rarely having to change tools. Take the exact same job and make a production run in 303 and 304, and I think you'll quickly see that your perceived savings aren't actually there at all..

Cheers

[gridley51]

Man I would hate to be an employee of yours. What you just said is the complete opposite of what every machinist has believed since the dawn of 304 stainless.

Also I doubt its any cheaper. I cut through 303 all day long like its butter, rarely having to change tools. Take the exact same job and make a production run in 303 and 304, and I think you'll quickly see that your perceived savings aren't actually there at all..

Cheers

Is it all right if I just call you Dennis?
As you`re cutting 303 all day you should be able to support your statement with some prices.
What`s the current prices per ton over there for 303 and 304?

[SirDenisNayland]

Is it all right if I just call you Dennis?
As you`re cutting 303 all day you should be able to support your statement with some prices.
What`s the current prices per ton over there for 303 and 304?

I don't know. I don't do material purchasing. I give a hand as far as quoting jobs by giving my input on our capabilities and expected cycle times, and if given an option of material let my opinion be heard but that is about it.

I manage the floor, manage and purchase tooling, design, program, and set up our machines. We have 4 swiss lathes, 4 conventional lathes, 3 mills and a myriad of manual mills, lathes, grinders, saws etc.

Quite frankly between all that and attempting to train people and just keeping the place running I don't have the time to manage that end of our operation. I am only an employee, but i know the materials I work with and I know the amount of tooling I go through on each.

I'm sure you've heard the saying "303 she's for me, 304 she's a whore"

And yes, you may call me Denis

[gridley51]

I don't know. I don't do material purchasing.

Couple of things wrong with your sweeping statements.
You don`t know what the material costs but you can tell me I`m doing it all wrong.
You talk about what machinists believe,I talk about what I know.
Stick to things you know about.

[SirDenisNayland]

Couple of things wrong with your sweeping statements.
You don`t know what the material costs but you can tell me I`m doing it all wrong.
You talk about what machinists believe,I talk about what I know.
Stick to things you know about.

Someone pee in your cheerios my friend? I never said you were doing it wrong, but look around, you're the only one who shares your opinion.

304 increases cycle times, increases tooling costs, and makes continuous uninterupted operations very hard to achieve.

I run high volume production, and 304 is nothing but a nightmare. It kicks burrs everywhere its very hard to break the chip. It's harder to drill, tap, mill, you have to go back over and clean up any milled edges, good luck getting a clean edge even with a brand new tool.

In my area of the cnc world seconds on a cycle time matter. I don't need to know the material costs to know that there is no way in hell i would save money using 304. This is not a belief, its what I know. Certainly the purchaser knows the same thing because if given the option we always go with 303.

If you really want, ill speak to the purchaser and let you know.

My guess is your one of these 15 minute cycle times on a part that should take no more than a minute kind of people.. at that point you're losing money anyway so I can see why you think 304 is the best.

[SirDenisNayland]

Spoke with our purchaser.
304 costs just as much if not more than 303.

Hmmm...

[gridley51]

Spoke with our purchaser.
304 costs just as much if not more than 303.

Hmmm...

Another post of the same quality as the rest of your drivel.Not a hard fact in sight.
You may want to consider a name change to SirDenisNaybrain.

[SirDenisNayland]

Another post of the same quality as the rest of your drivel.Not a hard fact in sight.
You may want to consider a name change to SirDenisNaybrain.

Much like your own post?

What applies as a hard fact? I'm not sure what you expected me to provide you with, a screen shot of a material purchase order? I'm supposed to take your highly controversial opinion as fact, yet when it comes to me nothing I say is any good?

You sir, are delusional. You make me laugh.

[SirDenisNayland]

Here, here is a "hard" fact for you



Obviously we would never buy from metal supermarkets and get our material directly from the mill (which I obviously cannot look up online), but you can see the differences in cost are negligible - they are essentially identical at higher volumes.

If you're running that much material, and I never have to change tooling on the 303 as I rarely do, vs 304 where you are changing tools often, having longer cycle times, among other prevailing issues 304 causes, well, your amazing $35 savings is quickly blown out the door.

Now where are your hard facts?

[leeputman]

Peace brothers, staying neutral on most of this thread.

What I have to add is tooling I used on a custom SS project I did a few years ago. Right now I do not recall if it was 303 or 304, it is the tool that amazed me. It was the wavy edge of the Minicut International. It was the 985 series and performed surprisingly well. I only had an old open cnc knee mill so I used cutting oil and low rpms but it worked. I do one's and two's type projects so my comments will not carry well for production.

Just some FYI

Lee

[mflux_gamblej]

I've trashed 4 x 1/4" and 1 x 1/2" endmills on the same workpiece.

My most recent attempt was:

1/4" endmill, 3850 RPM (252 SFM), 10.78 in/min xy feed (0.0007 in/tooth), 7.7 in/min z feed (0.0005 in/tooth). Step over is 20% of tool diameter (0.0500"), plunge depth is 0.0250". With these settings, I managed to mill 2 pockets, on the second the bottom of the pocket doesn't look quite right (very dull tool), on the third the tool just got rounded off and started eating further into the tool, now it is around 1/4" shorter and obviously trashed. These settings are based on SFM recommendations from maritool (backed off as they recommend for deep profiles) in addition to some notes I have from a friend who mills 304 all day on a HAAS VF2SS.


I've also tried around 1000 RPM, around 4 xy feed, 1 z feed, the tool actually died much faster this way. The material is 304 stainless steel, the cutters are TiALN coated carbide from MariTool.

My mill is an old interact 1 mk 2, 9.5 HP, workpiece is clamped hard to the table with a waste plate of Al underneath so I can mill through into that. I get a lot of chatter at slightly lower RPMs (around 3000-3300), almost no chatter around 1000 RPM, and pretty much no chatter up at 3850 RPM.

[mflux_gamblej]

I've trashed 4 x 1/4" and 1 x 1/2" endmills on the same workpiece.

My most recent attempt was:

1/4" endmill, 3850 RPM (252 SFM), 10.78 in/min xy feed (0.0007 in/tooth), 7.7 in/min z feed (0.0005 in/tooth). Step over is 20% of tool diameter (0.0500"), plunge depth is 0.0250". With these settings, I managed to mill 2 pockets, on the second the bottom of the pocket doesn't look quite right (very dull tool), on the third the tool just got rounded off and started eating further into the tool, now it is around 1/4" shorter and obviously trashed. These settings are based on SFM recommendations from maritool (backed off as they recommend for deep profiles) in addition to some notes I have from a friend who mills 304 all day on a HAAS VF2SS.


I've also tried around 1000 RPM, around 4 xy feed, 1 z feed, the tool actually died much faster this way. The material is 304 stainless steel, the cutters are TiALN coated carbide from MariTool.

My mill is an old interact 1 mk 2, 9.5 HP, workpiece is clamped hard to the table with a waste plate of Al underneath so I can mill through into that. I get a lot of chatter at slightly lower RPMs (around 3000-3300), almost no chatter around 1000 RPM, and pretty much no chatter up at 3850 RPM.

I've switched to smaller tooling (because that's all i have left today), and went more aggressive, it's working out when the endmill doesn't snap

Success seems to depend on whether on not I had clenched my left butt cheek while standing directly parallel to the feed override.

[UUU]

I've certainly found that manual drilling and parting off of stainless needs the agressive approach. I suppose the same for milling, as long as the tool can stand it.

I wondered, if you were cutting through into the aluminium, whether you were getting any pick-up on the tool?