Production Machining

MAY 2018

Production Machining - Your access to the precision machining industrial buyer.

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discharged upwards efficiently and quickly, especially in the case of ramping, drilling and helical milling. For this reason, the chip flutes on the end face must be large. Because of the design, the size of the chip flutes is more limited in the case of four-edge end mills than in the case of three-edge end mills. e Hoffmann Group has consequently developed a special milling cutter with only three cutting edges specifically for these applications. To ensure efficient chip evacuation (important when ramping), a point geometry such as a drill has also been developed and moved back toward the shank. is design allows sufficient space to reliably evacuate the removed material away from the working zone. Besides helical milling and drilling, the three-edge end mill can also be used for slots and side mills, covering all milling tasks without the need to change tools. Roughing and Finishing Modern HPC milling cutters leave behind such a smooth surface in some cases that the required finishing cut is no longer necessary. e new three-edge high-performance milling cutters from the Garant MasterSteel product line have been shown, for example, to eliminate the chatter marks that otherwise would occur when machining a fragile component made from 16MnCr5 steel. For components produced using processes such as additive manufacturing or modern casting processes (near net shape), a finishing cut is all that is required for the final machining of functional faces, which can be performed using a seven- edge HPC finishing cutter. At a constant feed rate per tooth, a seven-edge end mill produces around 17 percent higher rate of advance than a classic six-edge mill. With HPC milling cutters, the differences in quality regarding the geometry, the coatings, the carbide substrate and the edge preparation affect the tool life and the general performance. Design features such as the number of cutting edges and the shape of the end face play an important role in the machining task. Ultimately, advanced cutting tools can substantially shorten primary processing and non-productive times and significantly increase productivity by eliminating tool changes and superfluous work steps. For more information about milling tools, visit PM's Milling Tools Zone. LINK :: CONTRIBUTOR Eric Turner is the director of product management at Hoffmann Group USA. Tools with a higher number of teeth increase process efficiency. Milling cutters with five teeth are particularly efficient if the feed per tooth can remain the same during the manufacturing process. ese tools create 25 percent more feed compared with four-edge end mills and exhibit improved chip evacuation compared with six-edge end mills. Ramping, Helix Milling and Drilling When machining components, ramping, helix milling or drilling are often necessary for carving out pockets. However, conventional HPC milling cutters with four cutting edges often reach their limits because the swarf must be :: When pocket milling, the tool has to be able to plunge into the material by means of ramping, helix milling or drilling and be able to efficiently remove the swarf upwards. :: A knuckle form roughing cutter with five teeth also effortlessly cuts full slots with more than 1 × diameter into the component. TECH BRIEF :: 29

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