b'way out of the hole so the entry iswhen drilling. those coatings have surface imper-not misaligned. fections, such as droplets that harm Rutherford said the most strenu- Cover Up chip evacuation and a thickness at ous time for any cutting tool is duringCoatings commonly are depos- the drill tip that causes high surface entry into and exit from a workpiece. ited on cutting tools of all types totension at the cutting edges. In-These little tools cant afford anyminimize tool wear and extend cut- stead, a microdrill coating must be unnecessary abuse, he said. Theter life, but one size doesnt fit all.smooth and homogenous and min-more you can avoid loading and un- Gotti emphasized that coatings forimize surface tension to avoid cut-loading a tool, the better tool lifemacroscale tools are not suitableting edge chipping.and performance you will get. for drills smaller than 1 mm becauseLooking at coating thickness, Rak Even improper handling can be detrimental to microdrill life.I have been guilty of breaking one or two off with my finger, Ruth-erford said, and it is terrible to get it out of there. Its like a little razor blade splinter.To avoid tool damage, accurately entering a hole is critical.It must be very true, Rak said.However, a spot drill with a higher point angle than the microdrill to fol-low is needed typically when drill-ing a surface thats not clean, flat and faced, Rutherford said, noting that Kyocera SGS Precision Tools of-fers microspotting drills with frac-tional and metric shanks. Unlike the companys conventional high-per-formance drills, its microdrills dont have self-centering geometry.Gotti said Mikrons microdrills have a tip geometry specifically de-veloped to provide self-centering while also producing short chips and enhancing cutting stability.Thanks to web thinning and a re-duction of the chisel edge, he said, less penetration force is required contributorsKyocera SGS PrecisionTools Inc.330-686-5700www.kyocera-sgstool.comMikron Corp. Monroe203-261-3100www.mikrontool.comWalter USA LLC800-945-5554www.walter-tools.comctemag.com/cteguide.com19SmallParts.indd 19 6/17/21 11:09 AM'