Manufacturers flock to grinding gathering

June 8, 2005
Blohm exhibited a Profimat MC production grinder with a linear speed-stroke table.

The flexible Mgerle MFP 50 performs profile and creepfeed grinding, drilling, and turning on one machine.

The MFP 50's automatic toolchanger swaps out grinding wheels in 8 sec.

Blohm exhibited a Profimat MC production grinder with a linear speed-stroke table. Speed-stroke grinding is ideal for difficult-to-grind and heat-sensitive materials used in the turbine and medical industries.

An in-process regeneration unit, an option on Ewag's easygrind PCD and PCBN insert grinder, keeps grinding wheels clean. Doing so improves part quality and minimizes grinding times.

A global audience packed the first-ever Schleifring Grinding Symposium held in Thun, Switzerland. More than 1,400 end users and distributors attended technical conferences, machining presentations, and factory tours. They also witnessed the launch of new products from the companies of the Schleifring Group: Schaudt, Blohm, Studer, Walter, Mgerle, Mikrosa, Ewag, and Jung.

United Grinding, Miamisburg, Ohio, hosted the U.S. contingent. Attendees included a diverse group of small shops, large manufacturers, and dealers eager to see the new machines in action. Some came to the symposium looking for solutions to specific manufacturing problems, while others wanted to brush up on their technical knowledge.

The technical conferences covered a range of topics and were led by a diverse group of grinding experts from industry and academia. For instance, the conference session kicked off with a presentation on precision machining trends. According to the speaker, Dr. Fritz Klocke, head of the Fraunhofer Institute for Production Technology, Aachen, Germany, precision machining innovations are driven by a combination of new materials, new product design, and technological innovations of machines, tools, and processes. Such innovations, he said, include systems that combine hard turning and grinding.

Klocke's presentation was followed by sessions on highspeed stroke grinding, centerless grinding software, machining of PCD and PCBN tools, finishing concepts for mass production of shafts and chuck parts, grinding and dressing tools, and more.

In addition to the technical presentations, Schleifring also hosted 16 technical presentations featuring 24 grinding machines in action. Many attendees said this opportunity was a highlight of the threeday event.

Combination machining
One machine demonstration that caught the attention of many American attendees was the Mgerle MFP 50 grinding center, a 5-axis system engineered for machining small parts. This machine recently made its U.S. debut at the Eastec show in Massachusetts.

The MFP 50 grinding center tackles components requiring profile and creepfeed grinding, drilling, and turning. Such components include turbine vanes and blades, small turbine and compressor blades, fir tree and root shank faces, and shroud and Z-notch profiles.

Key features of the machine include an automatic toolchanger that uses a specific abrasive for different features — for instance, plated CBN for radial slots, vitrified CBN for blade W-forms, and conventional abrasives for radial slots. The toolchanger holds up to 20 tools and swaps out wheels in 8 sec. Maximum tool dimensions are 11.81 X 2.36 X 3 in.

Hydrostatic wraparound Y-axis guideways are another important feature. According to the manufacturer, they provide wearfree operation, high rigidity and load capacity, and vibration dampening. All main axes of the MFP 50 rapid traverse at 790 ipm. X-axis travel is 19.70 in., Y-axis spindle travel is 25.98 in., and Z-axis travel is 25.98 in.

The system has an overhead dressing unit, which allows for conventional, in-process, or continuous dressing of wheels. It's unnecessary to reset the tool; every time a wheel is changed, it is positioned against the spindle bearings. This allows optimal wheel position and dressing by tool offset. A 5.98-in. cross travel on the Z-axis cross stroke permits fine adjustment and CNC profile dressing of wheel shape features.

Precision grinding
American end users were also lured by a demonstration featuring Studer's S21 universal cylindrical grinder and S120 I.D. grinder. The combination of the two machines gives manufacturers of precision components, such as medical and optical devices, plenty of production flexibility.

The S21 machines everything from single workpieces to large batches. It tackles universal external cylindrical, noncylindrical, and thread grinding as well as a combination of external and internal grinding. According to Studer, adding automation makes the machine ideal for the aerospace, precision mechanics, and hydraulic/pneumatic sectors.

The machine features a turret wheelhead that swivels manually or automatically, an optional B axis, and a C-axis workhead for form and thread grinding.

Running alongside the S21 was the compact S120 production I.D. grinder, which handles parts up to 2 in. in diameter. Reportedly, it is suitable for small series production as well as highvolume applications.

The machine features a crossslide design for up to two internal grinding spindles. An extensive range of internal grinding spindles and special internal grinding modules provides modular configurability.

Speed-stroke grinding
In another machine demonstration, Blohm equipped a Profimat MC 607 production grinder with a linear speed-stroke table for highproduction machining of titanium and other difficult-to-grind materials. According to the company, speedstroke reciprocate grinding has a number of benefits over creepfeed.

For instance, there's a smaller contact area between workpiece and grinding wheel, which minimizes friction and subsurface plastic deformation. Blohm also reports faster materialremoval rates that reduce grinding time as much as 80%.

The table, with a working area of 13 13.78 in., permits feedrates of 328 ft/min at an acceleration of 65.61 in./sec2. A table-mounted dressing attachment takes care of conventional, CBN, and diamond grinding wheels.

Grinding PCD and PCBN inserts
The Ewag easygrind demonstration showed attendees a way to reduce grinding time for polycrystalline diamond (PCD) and polycrystalline boron nitride (PCBN) inserts. The demo included an explanation of an optional 2-axis controlled in-process "regeneration" unit.

Grinding PCD and PCBN tools to a "ready-to-use" state can be difficult. The face of the diamond wheel dulls in a relatively short time as the void spaces in the wheel bonding become clogged. At this point, the grinding face must be cleaned by "regeneration" with a SIC stick applied under pressure onto the grinding-wheel face.

During regeneration, a pressureregulation valve monitors the pressure between grinding wheel face and workpiece cutting edge and modifies the in-feed. The user defines how much pressure is required between grinding wheel face and the cutting edge of the indexable insert to be ground. When the pre-set pressure value reaches a high level, the easygrind automatically regenerates the grinding wheel, thus lowering the pressure to the pre-set value. After regeneration, the wheel is ready to resume grinding.

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