Colbalt milling cutters

I have a X2p mill and when using HSS cutters on steel I know the limits of the machine. I needed to cut some 4 mm slots in steel and used a Cobalt cutter for this, I found that it cut a lot deeper and with a reduced cutting speed than my normal HSS cutters could achieve. Are Cobalt cutters designed for lower speed cutting, as it done a great job on my slots.

Edited By Alfie Peacock on 21/07/2017 11:18:52

Cobalt steel is great but generally more expensive, i'd definitely say it's got a bit more durability than bog standard M40 HSS, they tend to be around 8% cobalt, anything more than that can fall into the category of "crobalt".

I nicked a big piece of cobalt steel from my old workplace to make cutting tools with and they're still sharp without a regrind. The extra rigidity makes it easier to get nice flat facets when grinding, takes longer but you don't get so much "dappling" when touching up the tool.

I would assume it'll perform just as well at high speeds as much as low ones. 

Michael W

Edited By Michael-w on 21/07/2017 11:30:34

I've only an X1, but an 11.5mm hss end mill i got cheap munches through mild steel just as well,& with as good a finish as the Hssco8 ones i have from same supplier.

I'd expect no difference in cut quality between hss & "cobalt" cutters from the same manufacturer.

"Cobalt" are capable of running a bit higher speed than hss,(more resistance to heat)~ at lower speeds there really shouldn't be any difference ?

"cobalt" are meant to be more wear resistant. I find with drills, cobalt can chip the cutting edge easier, but not noticed the same with endmills/slot drills.

Not managed to blunt it yet, so can't comment on relative longlivity.

HSS may be the poor cousin, but more than adequate a lot of the time for us hobbyists.

I have a load of the old carbon steel lathe tools need sharpening often but give a good finish, but I do agree hss is my choice

Mick