b'Chips Away Rutherford said any increase inA Smooth Finishedge roundness from a coatingGarud said Walter USAs leading causes a workpiece material to bedesigns of microdrills have coated said Kyocera SGS Precision Tools typ- pushed rather than sheared. flutes to provide a secure, reliable ically deposits a physical vapor de- An uncoated tool comes intoway to evacuate chips. In general, position coating on macrotools thatplay, he said, when the applicationthat capability also can be achieved is 2 to 3 m (0.00008" to 0.00012")is appropriate based on a shallowwith smooth or polished flutes.thick while the coating on a micro- hole depth and workpiece material. Reducing the cutting forces and drill is as thin as 1 m (0.00004"). ForYou can get away with using ansecure chip evacuation (are) even Walter USAThe DB133 microdrill features through-coolant capability.ferrous materials, the company rec- uncoated drill in a lot of nonferrousmore important (for microdrills) than ommends an AlTiN coating. materials like aluminum and copperconventional drills, he said, due to We want the coating to be thinalloys, Rutherford said. their small size and inherent weak-so we are not changing the dynam- In addition to iron-free alloys,ness in the drill body with such a ics of the chip formation because ofGotti put unreinforced plastics onsmall diameter.some slight variation in the geom- the list of materials that can beBecause the coating tends to ad-etry due to coating thickness, hedrilled with an uncoated tool. here to the cobalt binder in the said. We want that true geometryYou may prefer extra-sharp un- substrate, Rak cautioned that if not of the tool to do the cutting. coated cutting edges, he said. done properly, polishing flutes can Micro Hole Deburring Cartridges The Original and Only Producer for over 20 years For holes from 1mm through 2.3mm Lower cost per hole Available for Same Day Shippingfrom stock in most cases Consistent resultsUser Friendly Made in the USAwww.mideburring.com 810-227-1000 Brighton, Michigan20JULY 2021SmallParts.indd 20 6/17/21 11:09 AM'