Midwest Manufacturing News • July 2016 • Medical Manufacturing With The New 325Linear Grinder

Schiitte recently held an open house at its North American headquarters in the Detroit area. Many regional medical / ortho companies and others attended to see the demonstration of the new 325linear, a 5-axis CNC grinder with extended X- and Y-axis movement plus two auxiliary slides for workpiece clamping and improved grinding wheel guidance over the entire machining envelope. Micro tools, gun drills, hob cutters and complex geometries, as well as a wide variety of medical implants and orthopedic surgical tools can be accommodated on this new machine, which typically operates in the range of 2,500-4,000 RPM. The additional second auxiliary slide enables the 325linear to utilize tool guidance, part support, tail stock or workpiece pallets in operation. This new Schutte machine further expands the user's automation possibilities because it also offers advancements in wheel change and robotic workpiece handling. Various options were demonstrated at the event.

During the open house, representatives from the company's headquarters in Cologne, Germany, including Thomas Simmich, group leader for Schutte medical, conducted several presentations on the technology of the machine. In addition, part production was shown for a femoral knee joint, plus a rasp, broach, drill and reamer used in surgical procedures. Engineers Scott Topa and Matt Morgan from the Jackson, MI, facility also demonstrated the machine and gave technical presentations for attendees.

As the presentations explained, the 325linear grinder with linear drive technology ensures no part splay on femoral knees, for example, with high accuracy and no backlash. Further, Schutte provides customized software for the preparation of various implants as well as rasp/broach, drill/reamer and other specific tool programs. The onboard CNC further offers full cycle simulation for the user, so job estimating can be done more efficiently.

On the 325linear machine's A-axis, a user can install collet chucks, hydraulic expansion chucks or multi-range chucks. With the automated collet changer on the machine, workpieces with different diameters can be clamped with high concentricity in the unmanned loader station. The Schutte A-axis configuration on this machine also permits position-oriented clamping of nonrotationally symmetrical work - pieces. In this way, sequential workpieces with various roughing and finishing require - ments can be preset on the machine for continuous processing.

This new Schutte grinding system offers scalable automation with a 140-position tool changer, 5-24 grinding wheel magazine and a flexible robotic tool gripper for changing the smallest micro tools as available options. The same base machine can be utilized for continuous production of a single part in a work cell set-up or used for sequential one-off work as needed.

The 325linear features a universal rotation A-axis with a high level of concentricity (<0.0001° resolution) and pitch accuracy, while the XYZ-axis resolution is maintained at <0.1 microns. The swiveling C-axis for the grinding head has a 225° range of motion, also with <0.0001° resolution accuracy. The primary motor spindle operates up to 12,000 RPM with 15 kW max. drive output, while the grinding spindle option affords a max. speed of 24,000 RPM. Linear axis travel on the machine is 480 mm x 250 mm x 275 mm (XYZ).

The machine is offered with the proprietary SIGSpro (Schutte Integrated Grinding Software) as the programming interface, allowing users to assign clamping options for each grinding operation being performed. When the support and tool guidance system are used, preset distances from the grinding wheel to the workpiece can be defined and held constant. In 3- D mode, all cycle steps can be simulated, controlled and optimized for exact estimating, collision avoidance and even external workstation integration with the other workpieces.

All motion control on this new grinder is maintained on a Siemens 840D si CNC with compatible drive technology.

This new Schutte 325linear grinding machine is available for viewing at the company's North American headquarters in Jackson, MI, and will be in the Schutte booth during IMTS in Chicago.