Machining (slotting) wrought iron tips?

javand

javand

Joined
Oct 17, 2010
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Slotting a guard out of some wrought iron today, and it raped a premium carbide AlTin coated 4 flute carbide cutter in about 5 seconds. Admittedly, it's a very small slot (7/64 cutter), and it could have been chatter in my mill, but I've gotten beautiful cuts in damascus and stainless using 1/8 and 3/16 cutters of the same type.


Ended up switching to a HSS cutter, and got an "acceptable" slot, but it's far from what I've come to expect.


I've heard wrought is hard to machine, and I'm guessing since I was cutting right down a slag inclusion line that this was the primary issue, but anybody here have any first hand tips? I've got tons of large anchor chain I've forged down for making damascus and fittings with, and I'd prefer not to keep pinging cutters, if there's some trick I'm not aware of.

FWIW I was slotting dry, and it knocked the tips off all four flutes on the cutter as soon as I started feeding Y (I cut on the Y axis, since I can lock the X down better and see my work better), it didn't have any issue feeding Z.



Cheers.
 
I've never cut old iron like that, but I expect it is gummy, sticky and dirty.

Modern carbide with AlTiN is generally run dry in steel for improved tool life. I don't recommend cutting oil for this application, it really serves no purpose and just collects chips.

When slotting you might need an air blast to keep from recutting chips (nothing kills carbide faster). Also, don't try to cut the slot in just a few passes, give it dozens (limit your depth of cut to ~.020 on a less-then-rigid setup) and feed it hard enough to maintain a reasonable chip load. It should sound like sizzling bacon, not wailing banshees or a coffee grinder.
 
Hey Nathan, thanks for the response. I was cutting dry, and when I do cut wet with the mills I'm using flood with the Trim Microsol 585xt you recommended. ;) I buy the AlTin cutters specifically to run dry(BestCarbide brand, I've been super happy with their cutters so far).


I was only taking a 0.020 DOC, I always mill my slots with light passes, and never go over the half-cutter diameter rule of thumb. This stuff literally pinged as soon as I started to feed across the slot after I came to that DOC, but it was just the points of the teeth (square end mill).

Like I said, didn't have much problem with HSS, just a kind of ragged cut, but that's probably from the slag inclusions. I etched the material before I started slotting so I could see which way the grain was running and I was running parallel with the slag bands, and inside one.


I may have just run to the limit for small cutters on my smaller mill. It's pretty tight for a chinese BP clone, but it does have some run out.
 
I personally own the world's absolute most clapped out BP. The balls in the spindle bearings are less round than common gravel. And while it is capable of very little beyond stirring paint, I think it could spin that cutter without busting it.

If you put a dial indicator on a dowel in your spindle how much runout do you see? If you wobble it back and forth by hand how much play is there? There are a number of factors at play, but the spindle on a BP clone really shouldn't be a factor on a cutter this size unless there is a problem with it.

I can't help but think there much be some other something going on there.
 
Yea with all the silica slag in wrought it can kill any endmill in short order. I have taken to pre drilling the slot to remove as much material I can before I actually mill. This saves endmills. I normally use a drill at least .02 smaller than the finished slot to allow for run-out and slag wonder. I get a pretty clean slot unless the wrought is very dirty. Then I get the ragged edges like you described.
 
A radiused end mill might work better too, they seem to chip out a lot less.
 
Give the wrought a twist and spank it into submission!
I'm not kidding - it really makes a difference.
All three of these slotted with off-the-shelf 1/8" carbide end mills.






 
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