Steel surface finish

tcncj · Nov 21, 2019

Need some help with machining C45 steel.

I'm using new Korloy RM4 inserts with a Smoxh holder from Cutwel.

PC5300 grade insert (universal for steel and stainless)
Running at the recommended feed/speeds

0,15mm/rev
190m/min

WOC: 40mm
DOC: 1 to 2mm

Machine: VM10i

It's not that bad of a surface finish. But you can feel the grooves with your nail.
What's the issue here?
I'm not running coolant, only air.
Workholding isn't the issue
Very short gange length holder. I tried different holder with long gauge length, same issue.

gregormarwick · Nov 21, 2019

Not to be rude, but you're taking an economy class insert and putting it in an extremely economy class holder, both of which are designed for shoulder milling, and then wondering why your face finish is irregular...

The ridges are due to cutting edges being all over the place axially.

Mtndew · Nov 21, 2019

tcncj said:
What's the issue here?

Your inserts are at different Z depths and you're feeding too fast.
If all of your inserts are sticking out EXACTLY the same amount, then your finish would be exponentially better by default.

tcncj · Nov 21, 2019

gregormarwick said:
Not to be rude, but you're taking an economy class insert and putting it in an extremely economy class holder, both of which are designed for shoulder milling, and then wondering why your face finish is irregular...

The ridges are due to cutting edges being all over the place axially.

I'm always happy with the Korloy stuff so far. I don't do allot of steel and didn't want to spend 700,- Euro on a new insert mill and inserts.
I think it's because of the holder.
If you buy 20 inserts you get the holder for free. But that are crap I notice. I need to measure the pocket height difference. But a quick check shows that one insert sits lower than the other inserts.

Mtndew said:
Your inserts are at different Z depths and you're feeding too fast.
If all of your inserts are sticking out EXACTLY the same amount, then your finish would be exponentially better by default.

Ok I will check

mmurray70 · Nov 21, 2019

tcncj said:
I don't do allot of steel

If you cant get the inserts to sit at the same height and you really need a good finish could always run just one insert and adjust feed accordingly. Not very efficient but may get you out of a jam if QTY's are low. This would be best just for a finish pass with low DOC.

Tichy · Nov 21, 2019

mmurray70 said:
If you cant get the inserts to sit at the same height and you really need a good finish could always run just one insert and adjust feed accordingly. Not very efficient but may get you out of a jam if QTY's are low. This would be best just for a finish pass with low DOC.

Yes, what he said.

If you don't wanna bother with that, just try doubling the RPM on the final cut and take off 0.3mm. Or run it trochoidal/multiple passes.

You'll still see the tool path in the material but the surface fineness will be good/great.

michiganbuck · Nov 21, 2019

Could it be a cross-hatch because trailing side of cutter is making a cross cut.

Might run just a short length 1/2 inch or so perhaps just a skim cut so not making size and see what you get before the whole cutter is in the cut..
Agree Im a grinder guy and so know little about the VM10I
.006 per rev,,so if the lines are .006 apart then only one blade is high/cutting.

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