b'CHIPSAWAYEffective holemaking with microdrills requires a well-adjusted approach, especially for chip evacuation.By Alan RichterM ultiple methods are available to make a miniature hole. In the past, laser micromachining and elec-trical discharge machining were frequently the de-fault options because of technical limitations with the grind-ing machines used to produce the required geometries on solid-carbide microdrills, said Jake Rutherford, research and development engineer for Kyocera SGS Precision Tools Inc. in Munroe Falls, Ohio.The new grinding machines have a tremendous amount to do with making accurate geometries that small, he said.Nonetheless, a cutting tool manufacturer designs micro-drill point geometries to suit not just the intended applica-tion but the production of the drill, said Sarang Garud, prod-uct manager for Walter USA LLC in Waukesha, Wisconsin.The extremely small size of the drills makes it pretty hard to manufacture the drills, he said, and design for manufac-turing governs some of the drill design decisions as well.Garud said two important factors when designing micro-drills are cutting force reduction and secure chip evacuation.Rutherford said he considers any drill with a diameter smaller than 3.175 mm (0.125") to be micro. Kyocera SGS Precision Tools offers standard microdrills down to 0.041 mm (0.0016") and ones with through-coolant capability as small as 1 mm (0.039") for producing holes up to 15 diameters deep.For Mikron Tool SA, micro starts with diameters smaller than 1 mm, said Alberto Gotti, head of the Technology and Customer Project Center, whos based at the toolmakers headquarters in Agno, Switzerland. (Mikron Corp. Monroe 14JULY 2021SmallParts.indd 14 6/17/21 11:08 AM'