Fine Finishing of Holes
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Fine Finishing of Holes Christoph Gey Kennametal Shared Services GmbH, Fürth, Germany
Synonyms Fine boring; Precision machining of holes; Reaming
Definition Fine finishing of holes or reaming process belongs to the high-precision machining processes and is aimed to fabricate boreholes of high quality to serve engineering fits. The reaming process especially improves the surface roughness, diameter, and form tolerance of a borehole, whereas the hole location will not necessarily be effected. In preparation of the reaming process, the holes have to be predrilled or core drilled. The process can be divided into round and profile reaming.
Theory and Application History Fine finishing of holes was introduced to ensure fits to mating of two mechanical components as
either clearance, interference, or transition fit (ISO 286-1, ISO 286-2, ISO-R286 and ANSI B4.21978). Besides the multi-flute fine finishing tools were known for a long time, the guiding principles for single-blade reamers were inspired by the concept of deep hole drilling application with autoguiding functionality already established in the seventeenth century to produce canon and gun shafts of high quality with improved roundness and straightness. The research investigations in the twentieth century helped in understanding the working mechanisms of the deep hole drilling process and thus the usage of guiding pads. In the 1970s, the fine boring tool or single-blade reamer was developed (Kress 1975). The single-blade reamer became a tool for accurate and economic bore machining in mass production (Koppka 2009).
Kinematics The kinematics of reaming is comparable to the drilling process that incorporates a rotational movement and a linear movement in axial direction of the tool (Fig. 1). Reaming is basically a counter bore operation with thin chips. The target is to produce high precise holes in diameter with excellent surface and form quality. The reaming process is distinguished among three phases starting with the entering of the tool in the hole. The second phase describes the
# CIRP 2018 The International Academy for Production Engineering et al. (eds.), CIRP Encyclopedia of Production Engineering, https://doi.org/10.1007/978-3-642-35950-7_6404-4
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Fine Finishing of Holes
Fine Finishing of Holes, Fig. 1 Reaming process
Fine Finishing of Holes, Table 1 Cutting parameters – recommended feed rates are between 0.1 and 0.25 mm per tooth
Cutting speed in mm*min Workpiece material Steel Cast iron Stainless steel
reaming of the entire bore and the third phase the exiting out of the hole. The machining process is mainly determined by the cutting geometry in the front of the reamer. The geometry is mostly responsible for the diameter, hole geometry, surface quality, and chip evacuation.
Tool Materials Cutting materials used are solid HSS, cemented carbide, and cermets or brazed carbide, cermets, and PCD, PCBN insert versions on solid HSS or cemented carbide base bodies (Table 1). Guide pads usually consist of cemented carbide, cermets, or PCD. Most of the cutting
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