The double-disc grinding process is used mainly in mass production of flat precision components that must meet high specifications for dimensional tolerance, flatness and parallelism. In collaboration with the Japanese machine-tool manufacturer Nissei, Thielenhaus Technologies offers a compact machine solution on the American and European markets.
Frequently machined flat workpieces on double-disc grinding machines include piston rings, bearing rings, pump blades and impellers, valve plates, connecting rods, clutch discs and brake discs for cars and motorbikes, even for non-motorized bicycles. Other parts include precision discs, punched, fine-blanked and sintered parts. The parts are usually made from steel, cast iron, carbide, special alloys or ceramic. But the machines can also be used to grind magnetic materials, aluminum and special plastics.
The Nissei machine's design features include: closed-box frames, single-piece forged main spindles with integral GW mounting flange and a double-walled cast-iron frame design for temperature resistance and stability. Other precision features include the quill-slide feed system in conjunction with a worm gear, the associated patented pneumatic compensation for backlash compensation and precision bearings in the ABEC-7 class. Effective standards, such as an automatic tool-wear compensation system for the lower grinding disc by means of in-process measurement, are also integrated.
A swing-out housing for the rotary carrier allows the operator to change the grinding discs through the front opening just a few seconds after the spindles have come to a stop. With a portable wheel-changing aid this can be done in minutes. Depending on the tolerances to be achieved, workpieces can be machined using a rotary carrier throughfeed or carrier oscillation with infeed process. For tight component tolerances, the workpieces can also be planetary-driven between plunge-feed grinding discs.
When machining precision steel discs with a diameter of 70 mm, for example, the machine can achieve parallelism below 3 µm and surface results of Ra < 0.5 µm with a cycle time of 0.6 seconds. In other applications, the machine can achieve a stock removal of up to 0.6 mm per pass.
The machine also features a small footprint of 2 m x 2.5 m, including the control cabinet, which makes it suitable for small production areas. There are various automatic loading options for feeding and removing workpieces, ranging from part-stack magazines to robots.
In addition to aluminum oxide or silicon carbide, the machine can be equipped with super-abrasive grinding materials made from cubic boron nitride or diamond, which require appropriate dressing technologies. Conditioning is carried out by an NC dressing unit in the machine. This is equipped with an acoustic sensor for touch detection. For abrasive tools, twin rotary dressing discs are also available to create the macrogeometry. Microgeometry is optimized using a second aluminum oxide sharpening arm. All set-up procedures inside the machine can also be performed through a service door on the side, and controlled from there with a simplified control panel specially set up for the purpose.
The vertical double-face grinding machines are available in eight models with grinding disc sizes up to a diameter of 760 mm and 915 mm. Depending on the machine model and process, workpieces have a diameter of up to 220 mm. There are methods to grind piston rings of 600 mm and more. The thinnest pieces can be 0.8 mm thick.
Thielenhaus Technologies has been responsible for Nissei's sales in the USA through its branch in Detroit. All aspects of service, including dealing with enquiries, consultation, quotations and sample processing, through to commissioning, training, warranties and after-sales, are provided by the Thielenhaus teams in the U.S. and in Europe. As a result, customers have the advantage of a local contact that can be reached quickly throughout the project. For after-sales service, customers can use the Thielenhaus 24/7 service hotline.
For more information contact:
Thielenhaus Microfinish
42925 W. Nine Mile Rd.
Novi, MI 48375
248-349-9450
sales@thielenhaus.us
www.thielenhaus.us