Ultra-Precise Double-Disc Grinding Machines

For the large-scale production of flat precision components, Thielenhaus Microfinish (Wuppertal, Germany) offers a particularly cost-efficient, compact machining solution from their close collaboration with mechanical engineers at Nissei Corporation (Aichi Prefecture, Japan): an ultraprecision double-disc grinding machine tool characterized by precision, cost-effectiveness, ease of use and compactness.

During production of this machine, any expensive extra that wasn’t necessary for achieving the stipulated goal was foregone. Instead, precision was of paramount importance. The design of the machine focuses on a high degree of rigidity, with closed box frames instead of a C-frame, forged instead of turned tool spindles, clever positioning of spindle tilting mechanisms, and a double-walled frame design for temperature insensitivity. The all-important dressing process requires such rigidity as this to create the appropriate tool geometries.

Other highlights include a spindle sleeve feed system in conjunction with a worm gear, the associated patented pneumatic compensation for thread play, and high-precision ABEC-7 class bearings. Effective standard features include an automatic tool-wear compensation system for the lower grinding disc by means of in-process measurement. This leads to exceptional machining results. For example, parallelism below 3 µm and surface results of Ra 3.2 µm can be achieved on 68 mm diameter steel precision discs in a cycle time of 0.6 seconds. In another application, the machine removed up to 0.6 mm per pass.

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Ease of use is a crucial advantage. A patented swivel transport disc bracket allows the operator to easily change the grinding discs through the large front opening just a few seconds after the spindles have come to a stop. With an adaptable tool-changing aid this can be done in just a few minutes. Depending on the tolerances to be achieved, workpieces can be machined using a flow, flow/plunge or oscillation process. For the highest component specifications, the workpieces can also be propelled in the grinding gap with the appropriate transport disc designs.

Nissei has managed to compress this vertical machining solution into a footprint of just  2 m x 2.5 m including the control cabinet, which also makes it suitable for compact production lines. There are various automatic loading options for feeding and removing workpieces, ranging from stack magazines to robots. The vertical double-sided grinding machines are available in eight models with different grinding disc sizes up to a diameter of 760 mm. Depending on the machine model and process, rotationally symmetrical workpieces from a thickness of 0.8 mm and up to a diameter of 220 mm can be machined.

While Nissei is responsible for the construction, installation and running-in of the client’s workpieces, all service aspects, including dealing with enquiries, advice, quotations and sample processing, through to commissioning, training, warranties and after-sales, are provided by Thielenhaus for Europe and North America so that operators have the advantage of a local contact who can be reached quickly throughout the whole life cycle via the 24/7 service hotline. With this support, even small and medium-sized shops are able to purchase and operate a high-quality Japanese machine with a long service life and outstanding cost-effectiveness.

Thielenhaus Technologies GmbH, Postfach 201855, 42218 Wuppertal, Germany, + 49(0)2 02 481-0, Fax: + 49(0)2 02 45 04 45, www.thielenhaus.com.