A high-feed milling cutter (see Figure 5-17) is essentially a tool with a small entering angle and a small depth of cut. Due to its small entering angle (e.g. the Walter F2330 enters with a entering angle of approx. 15°), the cutting forces are mainly axial and radial, as shown by the red arrow in Figure 5-17b.
This small entering angle and small depth of cut brings two valuable uses to the high-feed cutter, or it can be used with a very large feed, most of which can reach 3.5mm/z per tooth; Or it can be machined with large overhangs, which can reach up to 8 times the length-diameter ratio in conventional feed machining. Similar to the previous two types of copy milling cutters, the large feed milling cutter also has several types of indexable large feed milling cutters, exchangeable head indexable large feed milling cutters, exchangeable head cemented carbide large feed milling cutters and solid cemented carbide large feed milling cutters, as shown in Figure 5-18. Figure 2-86 is also a high-feed milling cutter.
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The large feed milling cutter is a new type of milling cutter structure, and this new structure also has some problems that need to be paid attention to when using. Figure 5-19 shows a schematic of face milling with a high-feed milling cutter. When the step a. of the face milling of the high-feed cutter exceeds the effective diameter D of the cutter, unevenness of the machined surface will occur. Therefore, when face milling is performed with a high-feed cutter, the step distance a should be less than the effective diameter of the cutter D (note: it is the effective diameter of the cutter D, not the large diameter of the cutter). When a high-feed milling cutter is used for profiling machining, it is necessary to use CAM software to calculate the trajectory of the tool, but many CAM software do not yet have a tool model suitable for the trajectory calculation of the high-feed milling cutter.
Figure 5-20 shows the programming information for a high-feed milling cutter. Generally, when using a high-feed milling cutter for profiling machining, the pattern of the corner radius cutter introduced in the previous paragraph will be used instead, and the tool manufacturer may provide a programming value, which the programmer can use as the fillet value of the corner radius cutter for programming. This substitution creates a phenomenon of "undercut", i.e. some material that has theoretically been removed but has not actually been removed remains. This undercut is shaped like a ball crown, and the ball crown height X is very limited, as long as it is machined once with a suitable ball nose milling cutter or corner radius milling cutter before the final finishing, this undercut ball crown will not affect the final profiling accuracy. Figure 5-21 shows the programming information for three inserts for two high-feed milling cutters from Walter, while other similar cutters need to be requested from the tool manufacturer.
Figure 5-22 shows the machining characteristics of the Protostar Flash solid carbide high-feed milling cutter. Figure 5-22a shows that the chip thickness of a high-feed cutter is still smaller than that of a conventional corner cutter with twice the feed per tooth compared to a conventional corner radius, which indicates that the load on the cutting edge of the cutter is not very heavy.
Figures 5-22b and 5-22c show a comparison of the profiling error of a conventional corner radius cutter with a high-feed cutter. The comparison shows that the profiling error of the high-feed cutter will be smaller than that of the conventional corner radius.
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