Are carbide endmills better at wearing down in diameter vs HSS?

[rk9268vc]

Got some newbie questions for yall

I only cut aluminum on my mill

I have always ran HSS tools/ endmills

My problem is that new endmills make the outer dimensions of parts undersized, and after a while the tool wears in and the parts start becoming oversized
(new tool cuts too much, old tool cuts too little - talking 1-2 thou under vs over size)

Do carbide tools change dimension less than HSS as they wear?
Like is a dull carbide tool closer to nominal than an HSS?
Do carbide tools deflect less on profiling with 3xD cut lengths?

Tool life is less of an issue because all my tools die by crashing, it is more tool dimension stability.

Thanks!

 

[Milland]

As a general rule, a carbide endmill will be more stable when cutting aluminum. That's presuming good coolant flow and chip clearing, and not crashing it into steel or iron vise parts. I almost never use HSS endmills anymore, it's carbide all the way.

 

[rk9268vc]

how tolerant is carbide compared to HSS with minimal coolant?
I am using misters with WD-40 for coolant/ chip evacuation since my mill doesnt have an enclosure

 

[Johnhudson]

Sounds like your spindle is out a little.

 

[mhajicek]

Use a material specific carbide endmill with the appropriate coating, you can cut much faster and it will last months of high intensity production without changing size.

You have a stiff penalty if you can only do mist coolant with either type of cutter. Flood is good, high pressure TSC is best. I'm not talking about a few percent, I'm talking about orders of magnitude. I don't understand how anyone could be competitive today using HSS and mist coolant.

Oh, and if you're trying to hold a tolerance, you really should be using wear compensation.

 

[Milland]

I'd suggest not using WD-40 for a misting system, as the airborne particulates are harmful to breathe. Use a veggy-oil based lube if you want to use a mist.

Is WD-40 Toxic? [& Natural Substitutes That Work] - The Filtery

As to chip clearing, that's nozzle aiming and air pressure. If you have enough of both then you're good to go.

 

[CarbideBob]

....
Do carbide tools deflect less on profiling with 3xD cut lengths?
Tool life is less of an issue because all my tools die by crashing, it is more tool dimension stability.

Carbide deflects less since it is stiffer.
But is the problem actual tool wear or built up edge forcing the tool away from the part?

 

[rk9268vc]

I think it is actual tool wear. The tools stay pretty clean.

I had a program I have been running for days making good parts, tool wore out and gummed up, replaced it with a brand new tool and the parts are suddenly undersized by 2-3thou running the exact same gcode. I dont know how to use cutter comp and so dont use it, so it isnt that.

1/4" 4flute HSS endmill cutting 6061

 

[mhajicek]

I dont know how to use cutter comp and so dont use it, so it isnt that.

There's your problem. If you're not using cutter comp, it is that.

Learn how to use G41 and G42. When you first make a cut with a new tool, comp it away from the part to be safe. Then measure the result, adjust your offset by the error, and cut it again. It'll be pretty darned close to nominal. Then, as the cutter wears, you measure a part every now and then, and adjust your offset for the next part to stay as close to nominal as you can. This way you can use the same cutter for hundreds, or in certain alloys thousands of parts, all while holding tolerance.

I hold tenths all day on a Haas this way. All day yesterday and today I've been cutting parts within a .0002" zone. Not +/- .0002", but +/- .0001", for a total zone of .0002", in grade 5 Titanium, without changing the tool.

G41 and G42 Cutter Compensation

 

[rk9268vc]

well i just learned how to do cutter comp type wear in fusion and CNC12 and it works niiiice

so simple yet ive gone over a year and hundreds of parts without knowing how to do it lol

thanks chief