Four research projects reveal what may make the machines in the near future

The number of cases in which machines tool used for microstructures in components whose average dimensions often do not fit into the so-called "micro" category is growing. The topic is concerned professionals in the sector that have already developed four research projects that reveal what may make machine tools in the near future.

Hans-Jörg Albrecht, of Wissner GmbH: "We have been active for many years in high speed and high accuracy machining." "This project will help to bring these two disciplines that are basically incompatible."

Joachim Findeklee, Röders GmbH: "hydrostatic guides and linear direct engines make it possible the milling and grinding on a single machine"

Jochen Schönfeld, Hyprostatik Schönfeld GmbH: "the hydrostatic have become standard for machines of ultra precision, for cylindrical grinding machines and modern surfaces, and are applied in ever more lathes and milling machines"

For a year or so, we have developed four projects related to the mechanization of precision of 2µm or less pieces that cannot be the micro category. These studies are HiDynMolder, MechaSpeed, SonicPrecision and Microstruct.

Supervised by the Division of PTKA Production and Manufacturing Technologies (PFT), the Centre of Karlsruhe research, as the project sponsor company, these projects pursuing various objectives, all of strict practical relevance. After all, each project is accompanied by several companies that make up the practical experience gained during many years. The objectives of HiDynMolder and MechaSpeed are machine tools for the manufacture of tools and moulds that get essentially more geometric details and qualities of surface higher than of the current machines.

SonicPrecision pursues the machining of high precision components of axial symmetry of very fragile materials, and Microstruct wants to achieve the machining of ultra thin and duplicate structures on rollers of large stamping.

The multidisciplinary project HiDynMolder in which the participating companies and institutions have contributed with their own elements, is improving a machining center of five axes for the manufacture of flexible microcomponentes and microstructures. This project develops not only the current machine with a large dynamic and less than 1 µm precision positions, but also a spindle rotation of high frequency with a maximum speed of 250,000 rpm and a maximum double of eccentricity in nuts and bolts of 0.001 mm. There is also a module of laser machining with a beam of standard section of 2.5 µm and an optical measurement sensor for scanning by points with axial and lateral resolutions finer than 30 nm and ±0.5 µm, respectively.

The industry needs a machining center similar to the manufacture of moulds for the mass production of micro engineering products, for example microestructuradas mold cavities in micromoldes of injection or micropunzones of stamping. The middle and small scale production of products of engineering precision and microproductos is also possible on a single machine. The typical pieces are micromecánicos components for arthroscopic surgery. The machine can be also used for the manufacture of components for Microsystems complex (for example microrreactores, micromezcladores, microactuadores, microchip bioanalíticos, etc.).

On the other hand, HiDynMolder machining center conforms to structures in the micrometer-range - for example for precise machining of surfaces or functional elements of surface in microcomponentes such as optoelectronic coupled to microsensors hybrid modules.

These typical fields of application are of great economic relevance. Hans-Jörg Albrecht of the company Rolf Wissner, who coordinates the project, is convinced of the following: "We have been active in what refers to machining of high precision and high speed for long time." "This project will help to bring these two disciplines that are basically incompatible with each". The solution is based on high-precision milling machines that combine HSC with microfresado and microrrectificado tools. In detail, the responsible components are axes of highly dynamic machines, a high-frequency micro-machining spindle and a driver fast. At the conclusion of the project, expected HiDynMolder machining center details of components of ±0.5 µm in steel alloys with a maximum of 64 HRC hardness. Modules of integrated processes "mechanized laser material" and "optical collection of structures" partners of the project expect improvements to the systems of micromecanización available to date concerning the minimum structural size achievablemanufacturing tolerances and surface qualities. The first prototypes were already available since the last edition of the EMO 2005.

A swivel head such as those used today in a Wissner HSC milling machine. The HiDynMolder project will use HSC technology to new dimensions, for example with a rotating spindle of high frequency up to a maximum of 250,000 rpm speed.

Example of a piece by the combination of milling and grinding

The motivation of the MechaSpeed project is fed by the constant increases in demand by improving the terms of delivery and quality in the manufacture of tools and moulds, more specifically the greater speed and accuracy of the machining complex surfaces 3D.

Hydrostatic guides with special drives are free from wear, and stop, friction-free.

The machine that projects is aimed at development and the combination of the HSC milling and grinding dotted to reduce the RA values of the current 0.2 possible µm in steels tempered for molds to less than 0.1 µm and improve the accuracy of the work, even with more large pieces, 10 µm to 5 µm.

In the field of HSC milling, Röders GmbH, Soltau, is committed to monitoring this project which, in addition, several parts of the machine tool sector suppliers are providing their know-how. The objective of this project is the optimization of all the relevant subsystems in machine tools. This optimization includes for example, the development of the main spindle that is useful for processes of milling and grinding and exceeds by far the performance of the available spindles at present.

In addition, food drive shafts are direct designed to considerably facilitate the results of mechanisation through improvements in the design of the engine and the controller hardware and innovative controller strategies. The innovative designs and considerations to alternative materials are to optimize the design of the machine

Joachim Findeklee, head of development at Röders HSC machines, explained: "In 2003 Röders presented a machine of HSC milling machine equipped with rails engines and hydrostatic direct for maximum possible performance." "The MechaSpeed project is a consistent continuation of this technology."

In the SonicPrecision project partners are aimed at achieving the highest qualities of contours and surfaces, this time, however, in the field of turning of hard materials. The ceramics and especially hardened steels must be finished in a high-precision with extremely sharp monocrystalline diamonds. Previously, these materials had to be created if they had to submit the required tolerances, surfaces and concentricidades - an extremely long process.

The multidisciplinary project SonicPrecision to develop a lathe for hard materials is divided into two parts. The first includes the considerable growth of the precision of a lathe's series for the application, integrating hydrostatic guides, special and motor spindle drives. The second part consists of a unit tools assisted ultrasónicamente, in this case an oscillator installed under the support of the tool and by emitting ultrasonic vibrations that lifts the diamond tool mecanizadora a few micrometres along the direction of the feeder over 40,000 times per second. This reduced contact time allows a better cooling of the tool and discarded virtually wear. In addition, the affinity between the carbon content of the piece and the diamond tool cannot develop such destructive effect when she is machining steels.

If turned hard materials parts must present the maximum concentricidad, minimum tolerances and best surfaces, the lathe must adapt. Jochen Schönfeld, director general of Hyprostatik Schönfeld GmbH in Göppingen and head of the SonicPrecision project, sure is the ideal solution: "the hydrostatic guides with special hydrostatic drives not waste away, and when you estacionaras, not soortan friction." As a result, carts can position themselves within ±0.1 µm, and that for years. They also present best damping properties that make it possible for the high quality of the surface and concentricidad. At the same time, the hydrostatic oil keeps the machine at a constant temperature and reduces heat losses. That is the reason why the hydrostatic are already a standard for ultra precision machines, just right for modern surfaces and cylindrical grinders. It is also increasingly lathes and milling machines.

In addition, the SonicPrecision project uses a new hydrostatic motor spindle with a hollow shaft that promises to the partners of the project the optimal concentricidad with heavy loads and low heating.

Jochen Schönfeld explained: "without a doubt, the spindles with hydrostatic bearings produced a better concentricidad in the piece." Our program now includes hydrostatic spindles for grinding machines machines that generate concentricidades of 0.1 µm.

Alternatives in bearings ball can reach only about a 1 µm long term.

Structures of reflectors monocrystalline diamond tool

The objective of the multidisciplinary project Microestruct is a machine for the ultra precision machining of cylinder of large rolled - up to 600 mm in diameter and 2,000 mm in length, used for the manufacture of rollers for stamping to the production mass at low costcontinuous and repetitive surface with dimensions of pattern of 5 to 150 µm. such sheets are products that enjoy growing demand not registered so far, both in the experimental manufacture of aircraft with special surface structures ("sharkskin") of less friction and therefore lower consumption of fuel, as in the construction industry, which promises more child-friendly living conditions through the films of the Windows that allow addressing light.

But such films are only economic in continuous production, requiring microestructurados long diameter rollers. Making the ideal is a machining of ultra precision with geometrically predefined blades. Natural diamond cutting material produces sizes of pattern of less than a few micrometres in surfaces with a Ra hardness of less than 10 nm.

The supervisor of the project Michael Strobel, of LT Ultra-Precision Technology GmbH (Herdwangen-Schönach) is very familiar with the problems: "We manufacture optical surfaces in non-ferrous metals and the Microstruct project gives to us and other specialists the possibility of eliminating the problems encountered in the sector together." A challenge facing our work is the magnitude of the rolls that we need to mechanise. To date has not been possible to mechanise microstructures in large areas, so you must create a new machine concept. The result is a new machine of ultra precision that integrates three linear axes and a rotating shaft. High rigidity and good buffer properties are obtained by applying designs hydrostatic guides for linear shafts and bearings of the rollers. The cars are driven by linear motors. An alternative route is an axis of very high dynamics, also known as servo system of rapid tool, which can ensure to the axis x instead of the fixed the tool support when they are ones microstructures axisymmetric...

Evidence in the Perspex Degussa Division roller: a possible use of these microestructuas could include the deflection of light.

The central element to ensure the quality is a surface measurement system integrated in the control of the machine. According to the size of the pieces and the MicroElectroMechanical accuracy required, the machine fits in with a 3D integrated confocal measurement system for characterizing the mechanized microstructures. Expected high machining cycles need tool changes-automatic and camera-assisted tool calibrations, which must meet the requirements of extreme accuracy of this ultra precision technology (angular accuracy 0.5 seconds; positional accuracy 1 µm). The measurement of surface system starts automatic tool change when the quality of the surface does not reach the requirements.