Carbide cutters and torched / welded materials

[tractorman44]

Question #1: Does it hurt a carbide lathe tool or milling machine bit to cut into metal that was torched off then ground down? You know, grinding off the cooled but molten metal blobs before using the tooling to edge or surface ...

Question #2: What precautions are to be used when machining welded materials... Does the weld (7018 for instance) also damage the carbide tools ??

Question #3: How about the same questions above but using Tool Steel lathe cutting tools??

 

[DMS]

If you grind off the slag, then it is no different than cutting the base metal. Welding is a different story, as you are depositing a different metal. Most weld fillers are going to be harder/stronger than mild steel, but still no problem for carbide or even HSS (just slow things down a bit). If you are welding high carbon steel, then it can self quench, making things very hard indeed. This can be a problem for HSS, but carbide should still be able to cut it. Heat treating the material before machining should make that mostly go away.

 

[cjtoombs]

I use mostly ER-70S2 in my Mig welder, and it tends to be quite a bit harder than mild steel, probably mostly due to the quick cooldown quenching it. I've had a bit of a problem with the tool cutting more on the mild steel surrounding it and leaving a bit of a high spot where the hard portion is. I would just use the cutting speed for hard steel and take lighter cuts than usual. As DMS said, the best option is to anneal it after welding, but that's not always possible. Stronger weld alloys such as ER80 or ER90 would likely be even worse, and a 60 KSI rod would be not quite as bad (6011 or 6013).

 

[tractorman44]

Thanks guys, for the tips...I've always skirted the above mentioned scenarios not wanting to inadvertantly damage cutting tools. I knew it had to be possible, just didn't know what to do. At least now I have a startig point.