Dental Drills

Grindley was approached about trying to build a system of dental products for dental implants.  These implants were going to be a replacement for traditional dentures.

The customer could not find anything on the market that would fulfill their needs.  So they asked us if we wouldn't help them work out their design.

The major problem in drill human bone is to keep the temperature of the cutting zone down.  A 2° rise will kill the bone.  The other problem is to make sure that when they break through to the marrow that it doesn't grab.  You also want a good sharp cutting edge and "chip" ejection.  We tried drills with straight flutes but the bone waste wouldn't eject satisfactorily and the resulting friction increased the danger of higher temperature.

The drill blanks were made on a swiss from out of 17-4 ph stainless steel.   We drilled a small .5mm hole stopping just shy of breaking through.  The hole was counterbored and we held a tolerance of .0002 on the diameter.  After this we heat treated the blank and then we ground the flutes.  When the flutes had been ground we drilled a cross hole to connect with our .5mm hole that we drilled through to the end (or almost).  This would allow us to feed water to the drill point and keep the drilling zone cool.  Next, the heads had a hex ground on them.  Before we sent the parts to get TIN coated we would prepare the surface to get the heat treat scale off the drills.  This was done by using lapping compound in a small sand blasting cabinet.  After they were coated we pressed a small tube in the counter bore of the drill.  This was actually the driving mechanism.  The tube had been grooved and ground to fit a dental drill gun.