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Economical milling-introduction
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Optimization and improvements of milling operations are characterized today by various approaches, including the design of the cutting tool, its connection to the machine tool, the design of the insert geometry and the selection of the cutting tool material. In addition to the tool design and machining conditions, the use of high-speed machining, hard milling, dry cutting, high performance cutting and some other measures to improve performance can be mentioned. All of the above leads to much higher productivity, more economical milling and reduction of the overall machining cost per part.
The development of new inserts with more cutting edges, new tool geometries and new cutting tool materials leads to better efficiency, stability, accuracy and tool life. Using new tool-design methods like finite element modeling [FEM] enables today the optimization of shape and application even before producing the tools themselves.
For economical milling, high performance and optimal machining conditions, all parts involved in the milling process should be selected and optimized. Not only the milling tools and connections to the machine tool, but also the machine tool itself, the workpiece material and shape as well as the selected machining conditions should be optimized.
Development Directions of Milling Inserts for Higher Performance
The optimal insert geometry including the outer shape, the cutting edge configuration, the rake face, and the clearance face can improve performance in all industrial milling applications. In the past simple flat inserts with straight cutting edges were used. Today, more cutting edges have a helical profile in order to improve accuracy, tool life, surface quality, machining stability and cost efficiency.
The use of standard positive flat SPKN, TPKN or SEKN inserts, and screw-clamped flat inserts shows continually decreasing tendencies. Older cutter types with wedge or clamped inserts have been replaced gradually by cutters with screw-clamped inserts with molded chipformer, more chip space, and fine-pitch design.
The latest version shown in Figure 1 are helical inserts with non-parallel upper and bottom surfaces. These inserts developed during the last few years possess a rake angle δA(1) which is larger than the inserts' axial rake δA(1) [Figure 1]. The concept of the helical-cutting- edge geometry with the non-parallel surfaces explained in Figure 2 enables also a strong cutter body and high rigidity.
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