Small stainless parts, small endmills -- HSM/trochoidal still the way to go, or maybe a segmented rougher?

[Finegrain]

Hello,

I'm quoting a large quantity, small (1/2" x 1-1/2" x 1/4" thick) part in 303 stainless. I use HSM/trochoidal/Dynamic Mill on almost everything else, and that strategy looks like this, for 4 parts:



I'm thinking maybe of going another way on this part, like a segmented rougher:

Maritool 1/4" TiAlN rougher

I'd expect to go slower, but with higher engagement. Machine is 30-taper, 16k max RPM.

Anybody doing similar work, and can advise?

Thanks, and regards.

Mike

 

[GiroDyno]

Sub out to somebody with a fiber laser?

 

[Finegrain]

Sub out to somebody with a fiber laser?

Not a bad idea, but for this part, at this time, a machined finish is necessary.

Regards.

Mike

 

[DavidScott]

Garr makes a 3/16" diameter x 5/16" flute length corncob rougher for steel. I state this as it is the smallest I know of and I love the aluminum specific ones! Since you don't rough the slots in the ends or the elongated hole in the middle I assume 1/4" is too big for them. I often will use a corncob to rough out steel parts so would certainly compare cycle times with both to figure out which to use. I have been amazed at how well they cut ploughing straight through slots, quickly.

How big is the run and is it a one time deal or will you be doing them for awhile?

 

[lathenmill]

I do a lot of adaptive and in these situations I usually just contour ramp down full width with no issues.

 

[Pete Deal]

I do quite a bit of stuff like this in 1018. What I have settled is full depth one time around for roughing. Maybe slot it first full depth at one feed/speed between the parts then go around each once at a faster speed since it looks like the sides are considerably lighter cuts. I space my parts so I can get a 3/8" corn cob rougher through the middle. I like the Lakeshore Carbide Fireplug roughers for this. They have them down to 3/16", I've only used the 3/8" ones but maybe I should try smaller.. What I like is that they're super short and you aren't paying for a long cutter and more carbide that you aren't using anyway.

 

[Finegrain]

How big is the run and is it a one time deal or will you be doing them for awhile?

1,600 this time, unknown subsequent batches

 

[Finegrain]

Since you don't rough the slots in the ends or the elongated hole in the middle I assume 1/4" is too big for them.

Yeah, the slots are a bit over 1/8" so something different there.

 

[DavidScott]

I love the Fireplugs too and use both 1/4" and 3/8", but they cost more than their standard length roughers. I didn't know they went down to 3/16".

 

[DavidScott]

1,600 this time, unknown subsequent batches

Big enough for a few extra tools and time to figure out how to make them go fast.

What about sawing them to individual parts. That would save a lot of milling.

 

[Finegrain]

What about sawing them to individual parts. That would save a lot of milling.

Yeah, you're right. Don't really think about it with Al, but with stainless the extra time in sawing will be saved in machining.

 

[cosmos_275]

Maritool makes a 4 flute rougher at 1/8" . I used them on a job that had slot just over 1/8. No hsm. Worked well

 

[mhajicek]

I do stuff a lot like this as my bread and butter in Ti6Al4V-ELI. What I'll do is either space them far enough apart that the HSM toolpath gives the tool some room to move (3/16" EM in a 1/4" slot), or keep the HSM path out of the slot and then zig-zag down with a solid carbide high-feed endmill (3mm HFM followed by a 1/8" 5-flute finisher in a .130" slot). I find the Helical brand HFM's give really good tool life.

 

[Mtndew]

space them far enough apart that the HSM toolpath gives the tool some room to move

This is the way.

 

[dandrummerman21]

Are we talking 1/4" endmill between those 1/4" thick parts in 303? I'd just plow through it. It is 303. it's like butter.

Although I do agree with running saw cut parts, too. But if you didnt want to saw, just plow through.

I love hsm toolpaths but not sure I would bother here. What does the time difference look like compared to plowing around the whole profile at 15-30 inches per minute?

 

[Finegrain]

Are we talking 1/4" endmill between those 1/4" thick parts in 303? I'd just plow through it. It is 303. it's like butter.

Although I do agree with running saw cut parts, too. But if you didnt want to saw, just plow through.

I love hsm toolpaths but not sure I would bother here. What does the time difference look like compared to plowing around the whole profile at 15-30 inches per minute?

Simulation says ~15s to HSM saw cut blanks, 500 SFM, 8% engagement, 110 IPM. 4-flute EM.

Single (plowing) path is also ~15s, 300 SFM, 20 IPM (.0011" chipload). Same 4-flute EM.

So, no substantive time savings. Maybe tool life suggests one over the other?

 

[Mtndew]

When it comes to SS, I stumbled upon these beauties about a year or two ago. I've yet to see another end mill have longer tool life in SS.
It looks like they don't make a rougher in this coating though.

https://pct-imc.com/index.php/558-2/

https://pct-imc.com/wp-content/uploads/2022/11/558-Product-Literature.pdf

 

[crossthread82]

My favorite endmills for stainless are the VQMHV and VQMHZV line from Mutsubishi. They make 1/16 - 1/2 size and last a long time in jobs of used them on cutting 316. I'd just straight slot at full depth. Mits says 5000rpm and 29.1ipm for a 1/4 tool.

 

[Orange Vise]

Not a bad idea, but for this part, at this time, a machined finish is necessary.

Regards.

Mike

If you're open to tab-cutting these parts, you could sub out to laser or waterjet. Add a tab to the geometry on one of the long sides with two open screw pockets (ears).

Screw the blanks down to your fixture a few dozen at a time. Do all the cleanup milling work and then mill down the tab so you can break them off and clean up on a belt sander.

Similar to common multiaxis tabbing but starting from a roughed out blank rather than full solid. The main benefit is those ears which makes workholding much simpler.

 

[Finegrain]

When it comes to SS, I stumbled upon these beauties about a year or two ago. I've yet to see another end mill have longer tool life in SS.
It looks like they don't make a rougher in this coating though.

https://pct-imc.com/index.php/558-2/

https://pct-imc.com/wp-content/uploads/2022/11/558-Product-Literature.pdf

Where do you get these from? I'm not getting any hits from the usual suppliers.