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Milling inserts for 4140 hardened plate steel

1K views 3 replies 3 participants last post by  Chad G 
#1 ·
I am having great difficulty milling a side plate made from this crap, I've used up one 1/2" 3 flute carbide ball EM and working on a second. the first cutter wore fast taking light passes, the second one is not as far along as the first considering I'm taking .100 passes at one once (dumb mistake I bought 6" wide plate instead of 4" wide)

My indexable face mill has taken a beating and I am on the last set of corners for the mill before I trash it as Carboloy made it obsolete. It is my understanding that 4140 untreated is used in other high wear areas like spindles and actual insert tool holders.

I've got many HSS cutters but they only wear to a dull chatter in one pass of less than .025. I've spent more time changing and putting larger radii on my cutters to keep the tips from fracturing.

I am on a budget that is quickly not paying for itself due to this plate and the run time I've invested in it.

Also for those who have made side plates from this type of steel, what type of coating on the drill bits did you use? TIN, TiAIN or cobalt bits?

Never had this problem before, usually the carbide inserts that I've used in the past have held up for an entire day 10hrs of constant machining on alloys and stainless steels.
 
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#4 ·
Been at dentist today and started working on coolant recovery lines for the table, something about 3.5 gallons of liquid on my floor didnt make sense.

PM inbound 30cal.
 
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