The Helitronic Micro features a linear motor/torque drive technology. But the Micro has a radically new seven axis layout optimized for grinding micro tools. For example, the Micro has an X2 axis that automatically moves the tool to center during a grind, thereby achieving better accuracy on corner radii and ballnose forms on even the smallest tools. The machine includes a three-spindle grinding head for up to twelve wheels. And the Micro's new B-axis positions the wheel to grind clearance angles with the samepoint on the wheel throughout the grind.
These features help to speed up grinding by 30% and improve surface finishes by up to 50% than machines with conventional ball-lead screws. The optimal range for high precision production is from 0.020 - 0.50 inches (0.50 - 12.7 mm) in diameter, though the machine is capable of handling both smaller and larger tools. The machine also features an integrated FANUC robot loader for fast automatic tool changes. Plus the 1,000 RPM A-axis workhead can handle precise cylindrical grinds. That's particularly useful when making step tools.
Small machine tools and inherent miniaturized components are persistent development topics in scientific research. Miniaturization usually requires not only reproducing existing systems at a smaller scale, but also a complex integration of various functions into one single element. This concept is presented here by means of a miniature spherical grinding module (GrindBall). It combines a specifically developed magnetic bearing with fluid dynamic propulsion, thus enabling novel grinding kinematics and the possibility of integration in small machine tools. In this paper, the requirements of micro-grinding processes are introduced and the manufacture as well as performance of grinding spheres are discussed; the design of the magnetic bearing is presented and its functionality validated in experiments. Finally, results from numerical simulations leading up to the development of the propulsion system as well as its geometric layout are reported.
Axinte DA, Abdul Shukor S, Bozdana AT (2010) An analysis of the functional capability of an in-house developed miniature 4-axis machine tool. Int J Mach Tools Manuf 50:191203. doi:10.1016/j.ijmachtools.2009.10.005
Denkena B, Mhring HC, Kayapinar H (2012) Design of a compact fluidic XY-stage for precise positioning. In: Proceedings of the 7th international conference on micro manufacturingICOMM 2012 (pp 345349), USA
The authors wish to thank the German Research Foundation (DFG) for providing funding to this project, the members of SPP1476 for their excellent cooperation, and the North-German Supercomputing Alliance (HLRN) for granting access to their supercomputing facilities.
Micro grinding offers a high potential when machining micro structures in hard and brittle materials. In this context, a new machine tool the nano grinding center was developed, which allows to manufacture and apply ultra small micro pencil grinding tools without re-clamping. With this new machine tool, the influence of grain size, grain concentration, and process parameters on the material removal mechanisms was investigated during micro grinding of silicon with grinding tool diameters of 40m and 4m. Measurements of process forces, surface quality and accuracy were carried out and the results are discussed.
Micro pencil grinding tools (MPGTs) are micro machining tools that have a huge potential for manufacturing fully micro textured surfaces made out of a broad range of hard and brittle materials, finding use in industries like biomedicine and microelectronics. Due to the flexible manufacturing method used to produce MPGTs - the shape of the tool can be adjusted according to the task at hand. Complex freeform microstructures with various cross sections like dovetails or hemispheres can be produced cross sections that no other process can produce in brittle materials. MPGTs with diameters <50m however, suffer from a far too short tool life and far too slow achievable feed rates to make the process economical. As part of the tool development process, a parameter study is needed to understand the influence of some of the more important process parameters like feed rate, rotational speed and the tool inclination angle, as well as the grit size. A full factorial experimental design is conducted to determine the importance of each parameter, using an Analysis of Variance (ANOVA) statistical evaluation method. Using the knowledge obtained from the results of this parameter study, optimum parameters were selected for a second case study. Besides increasing the MPGT tool life, the goal was to achieve feed rates beyond 1mm/min.