Combining Hard Turning and Grinding

When a shop is in the market for new equipment, it generally has a certain need that a particular technology will fill. But over time, those needs can change, and certain specialized equipment may no longer be as useful to that shop. Today’s advanced technology allows machine tool builders to provide flexible, highly productive equipment that often gives shops multilayered capabilities. Such equipment allows a shop to adapt more readily to varying work. A machine designed under a platform concept—customizable for individual requirements while allowing simple reconfiguration for future demands—better prepares a shop for upcoming opportunities. During tough economic times, such features become even more important.

If a shop has sufficient capabilities for its turning requirements, but new jobs begin coming in that require some grinding work, the shop may find a need to invest in an additional machine. But if this grinding work is minimal and these workpieces are only produced in small or medium batch sizes, the purchase of a grinding machine may not be justified. A combination machine that is capable of both the turning and grinding work in a single setup could be the solution.

Blending Processes

EMAG now offers the VLC 250 DS turning and grinding center, combining the advantages of vertical hard turning with those of grinding. This machine is reconfigurable throughout its life cycle, providing adaptability to a shop’s changing requirements. By combining hard turning and grinding, throughput, transport times and storage periods can be substantially reduced to shorten overall cycle times.

The machine features a vertical work spindle and tools positioned below the workpiece to allow the turning and grinding chips to fall unhindered. All machine modules are designed to be mechanically sturdy and vibration resistant. The machine base is Mineralit polymer concrete for vibration damping, and the work spindle is designed to form an integral part of a sturdy quill that carries out its Z-axis movement on a high precision, hydrostatic guideway.

The tooling systems are anchored in the machine base and provide a stable basis for demanding turning and grinding operations. This design contributes to time-saving hard pre-turning work and achieving the best surface finish with a hard finish-turning or grinding operation. The number and design of the stationary tooling systems can be chosen to suit the individual machining requirement. Continuous monitoring of the machine temperature ensures a high degree of thermal stability. A cooling unit maintains suitable operating temperatures. The pickup technique used with the machine eliminates the need for a gantry loader or other loading device that would involve time-consuming resetting work.

Quality Control

The VLC 250 DS is designed to handle complex manufacturing processes, from turning work at high chip removal rates to gentler grinding operations. By offering complete machining in a single setup, it eliminates reclamping errors. Measuring operations can be included as well to ensure optimal integration of quality control functions into the overall process. The measuring probe is located between the machining area and the pickup station, clear from the ingress of chips and coolant. Because the workpiece remains clamped during the gaging process, intermediate measurements can also be taken.

The Origins of Inverted Vertical

Emag has been a manufacturer of lathes and special purpose machines in Europe since 1952. In 1969, the company introduced a series of program-controlled, modular turning automatics, and by 1977, it had begun worldwide distribution of highly automated CNC turning cells and manufacturing systems. But it wasn’t until 1992 that the company introduced the world’s first vertical turning center with a pick-up spindle.

Company president, Norbert Hessbrueggen, was meeting with a colleague, Jean Paul Nodler, who was suggesting adding a vertical machine to the company’s lineup of horizontal production lathes. Sitting face to face across a desk, Mr. Nodler sketched a typical VTL with the main spindle in the base and the tool carrier over head.

What Mr. Hessbrueggen saw from his angle, though, sparked the idea for the inverted vertical pick-up lathe, flipping the traditional VTL design 180 degrees. This configuration allows the spindle to do double duty, loading and unloading parts and machining finished parts. Components that provide the machine’s precision (ways, ballscrews, glass scales, servodrive motors) can be placed outside the workzone, away from chips and coolant contamination. Gravity takes care of moving chips and coolant away from the manufacturing area.