I will keep this as short as possible, I got a 2.5" face mill that takes SEHT inserts and I can't seem to keep them cutting nice. I got the face mill used with my mill, and the inserts that where in it seemed to not cut worth the poop, so being used I figured the previous guy probably got all the sides dull on them so I ordered some Kenametal SEHT 43A6 inserts (from my very limited experience with carbide my research said they should work good). Put these new inserts in yesterday and while facing off a piece of mild steel, doing 270RPM (the slowest my mill goes), .005 depth of cut, the inserts lasted maybe 5 minutes before the chips turned into dust. So I turned all the inserts to finishes my job, and again maybe 5 mins the chips started to turn into dust. What the heck is going on here? What am I doing to cause these inserts to dull so fast? How long should they last for? 5 mins seems awful low. If it matters there is 4 inserts on the mill. Are they the wrong inserts? Thanks everyone!
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Carbide Inserts not lasting long, what am I doing wrong?
- Thread starter Armourer
- Start date
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- Nov 23, 2017
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- 1,191
Carbide wants to go faster than 270RPM.... I run a 6" face mill on my Horizontal Mill at 3000RPM......
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- Jul 31, 2020
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If RPMs or feed are too low, you produce heat and wear on the carbide as versus cutting it. That is one possibility, but I haven't done the math on your SFM or looked at the recommended values for those carbide cutters. Another is Material, how certain are you the steel is what you think, and how bad is the scale on it? Too deep of a cut, with too low of an RPM can also cause faster failure. Once again, look up the chart for your carbide of choice and run it through an online calculator. The experienced people here can take an immediate look at what you said and likely give specific guidance on ideal values.
The another is a darker possibility, A lot of Chinese Knock-off/Counterfeit carbide is showing up on the market. They have the right looking labels and boxes, but are not what they claim to be. They don't last like the genuine article and get micro-fractures and edge erosion rather quickly. You can confirm this by tossing in a quality (about 50ish buck) 1/2 inch end mill, and seeing if it cuts normally without excessive wear. If it runs well, then either your face mill (carbide holder) is suspect, or the carbide inserts.
The another is a darker possibility, A lot of Chinese Knock-off/Counterfeit carbide is showing up on the market. They have the right looking labels and boxes, but are not what they claim to be. They don't last like the genuine article and get micro-fractures and edge erosion rather quickly. You can confirm this by tossing in a quality (about 50ish buck) 1/2 inch end mill, and seeing if it cuts normally without excessive wear. If it runs well, then either your face mill (carbide holder) is suspect, or the carbide inserts.
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- Apr 14, 2014
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- 3,161
I would also look up the brand and size of the face mill and see what type of inserts the manufacturer recommends. I picked up a face mill a few years ago that didn't have the correct inserts installed. Apparently the seller had some around that fit, but the profile wasn't correct for the mill. The proper inserts were about half the size and a totally different profile than those that were in it
Thanks for the help guys, I realize that 270rpm is slow for carbide and thats what I ran it at with the old inserts to get a decent finish (any faster and would get chatter). With saying that, the old inserts had no markings of maker or anything. I am pretty new to machining and never thought that maybe with these new inserts I got they may like to go fast, and it never dawned on me that going slow would produce more heat! But that makes perfect sense. What RPM should I spin this sucker at then? I have 1.5hp knee mill thats pretty rigid!
As far as the mill scale, I knocked it all off with my old inserts then used the new ones once I had it all removed, I went approx .030 deeper once the mill scale was removed. I know that mill scale is really hard on inserts, thats why I used my old ones to get rid of it first and then use the new ones for the finishing pass. I will have to try and order a high quality end mill and try that as well! The Kenametal inserts I got where off eBay from somewhere in the states and look like the real deal as far as packaging goes, I have some old Kenametal insert that came with my lathe and the boxes look the exact same. Also the face mill is a Korloy, not a cheap Chinese one. Thanks all for the help so far.
As far as the mill scale, I knocked it all off with my old inserts then used the new ones once I had it all removed, I went approx .030 deeper once the mill scale was removed. I know that mill scale is really hard on inserts, thats why I used my old ones to get rid of it first and then use the new ones for the finishing pass. I will have to try and order a high quality end mill and try that as well! The Kenametal inserts I got where off eBay from somewhere in the states and look like the real deal as far as packaging goes, I have some old Kenametal insert that came with my lathe and the boxes look the exact same. Also the face mill is a Korloy, not a cheap Chinese one. Thanks all for the help so far.
I will have to see about contacting the manufacturer, it is a Korloy face mill and they don't list it on their website any more! That is something I will have to look into as well!
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- Apr 28, 2014
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What is the grade of the carbide you purchased? Is it for ferrous metal? Sometimes insert grades for non-ferrous will not perform well cutting steel.
Who did you buy the Kennametal from?
Kennametal and other name brands are getting counterfeited left and right. I've got two packs of Mitsubishi that are.
Picture was correct on the eBay listing, what I received was different. Close, but the fonts and color of the packaging were off.
One other thing to check for is wear in the insert pockets on the face mill. Even an ever so slight bit of play will cause an insert fail.
Who did you buy the Kennametal from?
Kennametal and other name brands are getting counterfeited left and right. I've got two packs of Mitsubishi that are.
Picture was correct on the eBay listing, what I received was different. Close, but the fonts and color of the packaging were off.
One other thing to check for is wear in the insert pockets on the face mill. Even an ever so slight bit of play will cause an insert fail.
- Joined
- Aug 2, 2020
- Messages
- 43
what are you cutting?
Thanks for all your help, and sorry for not posting a update! I took all your guys suggestions and started with the easiest ones first, and I cranked up the RPM to 1000RPM and it seemed to cut much better, so I thought about cranking up some more. Went up to 2000RPM and my surface finish turned out like a mirror and milled away for a hour with the inserts lasting the whole time and still being sharp when I finished. So with these new inserts I guess they like running fast, where the old ones I had definitely didn't like it fast. Maybe the old inserts I had where the ones that gave grief (no idea the brand or anything else as they came with my mill) all along and the new Kenametal ones turned out to be way better. Thanks again all for helping a new machinist out!
