MAY 2017

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Page 8 of 23 | The Machine Tool Search Engine 7 ABOUT THE AUTHOR Barry Rogers recently retired as global director of sales at Haas Automation. Prior positions include director of global sales and marketing for Sunnen Products, and national sales and market manager for Renishaw North America. He also has served as general manager of Cincinnati Milacron's LK CMM division in Detroit, Michigan. Barry recently started Alpha Strategies, a Chicago-based consulting firm which he serves as president. a lot of fine 3D surfacing, the small chips produced may slip through the cracks of a standard chip conveyor. Discuss alternate conveyor types with your dealer. Aluminum may adhere to sidewalls of the conveyor or float into the coolant tank. Too many chips in the coolant can cause the coolant mixture to break down and lose effectiveness. Consider upgrading to drum- type filters or paper filters for the coolant system to prevent this. Integrated scrapers that remove chips from conveyor sidewalls are also helpful. Steel chips are usually easier to manage than aluminum, because steel is heavier and less likely to cling to walls or accumulate in a high- production setting. For cutting cast iron, special drum-style conveyor/separator systems will provide outstanding chip removal and keep particles as small as 50 microns out of the coolant. PROBING AND TOOL SETTING Spindle probing and automatic tool setting become almost mandatory when operating an HMC. The construction of an HMC makes using dial indicators and edge finders very difficult and time-consuming. Whereas the operator can open the door of a VMC to set a tool length manually, setting tools on an HMC needs to be done automatically. Whether you use an off-line tool presetter or an on- machine tool setter, automating the process is the only way to go. Additional options for automation include detecting broken tools and dynamically measuring tool length and diameter to eliminate spindle or tool runout. Spindle probing on an HMC is likewise compulsory. Machining multi-sided parts or having versatile tombstones requires using numerous fixtures and establishing multiple work offsets. Using a spindle probe makes it unnecessary to build expensive fixtures to locate the part precisely. The probe locates the part and then automatically determines and updates the work offsets without operator intervention. The spindle probe can also establish the center of the rotary table or pallet to avoid runout, detect thermal growth for compensation routines, and reduce off-line inspection procedures of the machine. HIGHER PROGRAMMER SKILLS NEEDED Programming an HMC requires a higher level of skill and experience. The HMC programmer must deal with multi-sided work, handle coordinate translations in some cases and provide work offsets for each pallet, to mention a few of the extra duties. The HMC programmer must have CAM software with the features and capabilities to support this level of programming. Programming support is also required if broken tool detection and part probing are incorporated. REDUCE OVERALL COST Compared to the VMC, an HMC offers more flexibility, increased spindle utilization, higher productivity, less work in process and faster work throughput. An HMC can provide better tool life, higher part quality and superior surface finishes. Labor costs for production with an HMC are lower as well. All said, it is not surprising that spending on HMCs has risen substantially in recent years.

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