Today's state-of-the-art in grinding can be summed up in three words: fast, lean, and flexible. Machines, abrasives, and supporting technologies are all focused on delivering quality and productivity at an ever-lower cost-per-piece while providing the flexibility to support sophisticated capital recycling strategies. It's a tail order, but today's technologies are up to the task.
High-speed grinding is an evolving technology with great promise for reducing part cost while increasing productivity. It has been known for at least 35 years that in some processes the highest possible wheel speed should be used because increasing speed results in lower forces and reduced chip thickness which translates into lower cost per unit of metal removed.
"High-speed," of course, is a totally relative term, one that is defined by the technology available at any point in time. In the '80s, for example, high-speed grinding meant aluminum oxide wheels running at 60 m/sec on a machine with frictional ways, cam-driven contour generation, belt-driven spindles, a single-point diamond dresser, and a proprietary control.
Designed for speed
Things are different today. A high-speed system includes one or more dynamically-balanced CBN wheels on special mountings running at speeds that may exceed 300 m/sec, driven by a powerful motorized spindle with hydrostatic bearings, mounted to a stiff, accurate machine with linear motor axis drives, hydrostatic ways, a superprecise, sensor-based wheel truing system, and a PC-based, open architecture high-speed control.
Virtually nothing used in today's systems was available commercially in the '80s, and that speaks volumes about the pace of grinding technology development in the last few years. The most important aspect, though, is that today's system is precisely that--a system--in which each component is designed to work with the other components to increase precision and productivity.
CBN wheels, whether plated or vitrified deliver the strength, thermal characteristics, and wear-resistance to make high-speed operations both possible and economically feasible. But without motorized spindles and linear motor axis drives it is very difficult to realize those advantages. And because the active abrasive thickness on a high-speed wheel may be only 5 mm, an extremely precise truing system is essential for economical operation. Finally, the control must be fast and powerful enough to keep up with the process.
The bottom line on...