Production Machining

MAY 2018

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

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Selecting the Right Milling Tool Contributed by Eric Turner M odern high-performance milling cutters combine high cutting data with long tool life and, consequently, contribute to an increase in the productivity of manufac- turing processes and to a more favorable cost structure. However, certain factors must be considered when selecting tools, particularly in the case of flexible processes such as milling. For example, non-productive process times can be reduced by changing tools less often. In the case of small toolchangers, the ability to process different materials with a single tool may be of benefit. To maximize the potential of the machine tool, the user generally should choose between using a special tool or a universal tool. HPC milling cutters now have unequally spaced cutting edges and an uneven helical pitch because geometry is key to the performance of a milling cutter. This design ensures less vibration and contributes to smooth cutting action. Performance and Durability During high-performance milling, tools should be designed for high process speeds and the resulting temperatures (which can promote premature tool wear). Such high temperatures also cause oxygen to become reactive, so coatings should be resistant to oxidation as well. e coating is supplemented by an optimized fine-grain substrate that increases both toughness and hardness simultaneously. Edge preparation is also important. A homogenized, deliberately rounded-off cutting edge prevents the growth of cracks and chips, slows down wear and ensures slow and even abrasion. Milling cutters with these characteristics can be used for machining a variety of materials. With these requirements in mind, the Hoffmann Group has designed its milling cutters from the Garant MasterSteel product line to complete various machining tasks, including side milling and milling of slots and ramps, helix milling and even drilling. Side Milling and Slots For users who primarily side mill components or mill slots, using universal machines with toolchangers to do so, conven- tional roughing end mills with four cutting edges work well. ey can also undertake tasks that indexable insert tools are otherwise intended for, such as if the surface of the compo- nent also must be milled flat. e Garant MasterSteel HPC milling cutter eliminates the need to change tools and can reduce non-productive time and processing times when machining a general structural steel welded construction. Full Slot Milling A knuckle form roughing cutter works well for milling deeper, full slots with more than 1× diameter and for machining delicate components. Due to their knuckle form profile, these HPC milling cutters produce less cutting pressure and expose the component to less stress. e particularly short swarf chip evacuation also increases process reliability. :: Conventional four-edge end mills are particularly well suited for side milling and slots. Other milling cutters can also undertake these tasks, but knuckle form milling cutters do not leave behind such a smooth surface. :: Particularly efficient chip evacuation and a milling cutter tip that is similar to a drill are required for helix milling and drilling. Several tools of this type can be used as a universal tool for all milling disciplines. TECH BRIEF 28 PRODUCTION MACHINING :: MAY 2018

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