Through coolant holes in drills...how do they do that?

[Janger]

Lately I've been reading about coolant delivered through the tool to allow increased material removal rates. Pretty interesting. So HOW exactly do they put a twisty hole through a solid carbide drill bit? This guy from Iscar explains it at a high level. I still don't really understand how this approach would work. Maybe that is a trade secret?

Fishing line? inside molten metal? Huh? why wouldn't it just melt and disappear? Is it molten carbide? Or is the fishing line a euphemism for some other string material? Tungsten wire?

 

[Janger]

Here is somebody's quite cogent answer over on practical machinist. https://www.practicalmachinist.com/vb/general/coolant-thru-mini-drill-142773-post728210/#post728210

 

[Tom Kitta]

*micro "concrete" mixture* is key here - you form carbide tooling like you would form concrete stuff, using forms.

I almost bought some powder at auction - but it went too high.

 

[johnnielsen]

We received thru hole coolant tools with the used machinery we imported from Scandinavia in the late 70s and early 80s but they were high speed steel so they have been around for a long time.

 

[Tom Kitta]

I have French made HSS with through coolant drill bits.

Believe it or not that at least small HSS drill bits are extruded with holes in them. I would think it is much harder to make HSS with coolant holes then Carbide.