Indexable Milling Inserts For Steel?

Dan_S

Dan_S

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What's everybody using to get a good surface finish on steel?

I've been playing around with a 1-1/2" 45 degree face mill, that uses SEHT inserts, and while I can get an ok surface finish it's nothing to brag about. If i switch over to the aluminum inserts I get a fabulous finish on every grade of aluminum I've tried.

This is the finish I got in hot rolled 4140, the close up looks worse than it actually is. Sometimes the middle of the cut has a glass smooth finish to the touch. The roughness is always at begging & end of the cut, when only one insert is engaging the work at a time.. I think the issue is that wiper style insert is just to much for my machine in steel.
4140.jpg

4140CloseUp.jpg

this is the face mill & inserts.
faceMill.jpg
insert.jpg
 
are you blowing the chips away as you go?
 
That looks like a typical finish for 4140HT that I deal with often. You want a "polish" finish, get your RPM's up there around 2,000-3,000 and take a light cut say .010" deep with a decent feed. Play with the feeds until you get a finish like you want. Personally, I get best results using a sharp rounded nose radius, like a no. 3 or 4 radius, instead of the wiper on the insert.
 
4gsr said:
You want a "polish" finish, get your RPM's up there around 2,000-3,000 and take a light cut say .010" deep with a decent feed. Play with the feeds until you get a finish like you want.
Click to expand...
my machine maxes out at 2k, and about ~20 ipm (30 for rapids), and iv'e tried them all. The pics above are 1200 rpm and 20ipm. At 2k rpms, I start getting some decent hammering, and a smeared finish no mater what feed I use.

4gsr said:
Personally, I get best results using a sharp rounded nose radius, like a no. 3 or 4 radius, instead of the wiper on the insert.
Click to expand...
SEHT's ? I haven't seen any with a radius, just wipers.
 
I'm using these Iscar inserts, they produced nice blue chips that yeah shot off like popcorn in all directions. I used them to surface this t-nut to the proper thickness, mind you on the old 12z mill which was tram and backlash challenged.

I was asking my brother about HR/CR steel and what a crappy surface finish I was getting on my lathe. He said that's just the nature of that steel. On his big mongo CNC Mori Seiki lathe he gets a mirror finish taking heavy cuts while ruffing, but then on the finish pass the surface finish turns dull and lifeless. And that's on a 13,000 lb lathe.
 
Last edited by a moderator:
coolidge said:
I'm using these Iscar inserts, they produced nice blue chips that yeah shot off like popcorn in all directions.
Click to expand...

Those still have a wiper, but they look a little sharper than what I've been using. I might have to give them a try if I can find a good deal on them.
 
Do you guys have any opinions on the APKT style face mills? I've been doing some research tonight, and they seem to have a much larger range of corner radiuses, and chipbreaker geometries.
 
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