Tham khảo tài liệu 'machining and monitoring strategies part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Machining and Monitoring Strategies 521 a Inspection of a batch of mm micro-drills - held in a cassette in a Rollomatic grinding machine. Courtesy of mt micro tool GmbH b Detail of micro-drill geometry showing chamfer which is critical for evacuating chips effectively. Courtesy of mt micro tool GmbHỊ If the insert cutting edge is set below the center of the bore the insert will rub and could break. MICRO-END MILL GEOMETRY - SOLID MICRO-GRAINED CEMENTED CARBIDE. Courtesy of Triple-T Cutting Tools. c Micro-boring tool for boring holes @ 4 mm Courtesy of Horn USA J d Micro-boring tool setting height is critical to its machining performance. Courtesy of Horn USA Setting the insert cutting edge on center ensures clearance between the insert and the bore. MAGNIFIED DETAIL FOR EXAMPLE MICRO-MACHINING OPERATIONS - @ mm GROOVING BORING THREADING FACE-GROOVING 8 X ICourtesy of Horn I K f 03 . . r - mm Large location area on both top and bottom of insert. Through-insert coolant supply. Minimum removal of carbide to give maximum insert strength. Solid micrograin carbide insert available in coated and Positive uncoated gascutting j geometries. ÍỈĨWĨĨĨĨĨ Figure 255. Some typical micro-tooling drills and boring tools 522 Chapter 9 otherwise lead to premature tool breakage. While another note of concern when micro-drilling is its penetration rate. If too high a drill feedrate is programmed then the micro-drill will immediately fracture. Some micro-drilling manufacturing companies either recommend a single-flute assymetric drill geometry - allowing high chip loads coupled with an efficient chip evacuation process conversely another approach is to increase the number of drill flutes but this may cause chip evacuation problems with sticky workpiece materials. At present micro-drills can normally drill holes with L D ratios of 5 1 but it is anticipated that these L D ratios will soon be up to 10 1. In any microdrilling operation the first few .
