IMMS has developed a drive that positions objects with nanometer precision.The lifting modules have now been optimized for production and measurement technology.Image 1 The lifting modules developed at IMMS were optimized for use in production and measurement technology.Positioning systems in semiconductor production and high-precision measurement technology have to move more and more precisely in order to cope with ongoing miniaturization.For new manufacturing processes, ever larger vertical adjustment ranges are required.IMMS has already developed a 6D direct drive for this, which positions objects freely in space with nanometer precision and actively controlled in a travel range of 100 mm diameter in a lifting or lowering range of 10 mm.The lifting modules have now been further developed in order to optimize the system for use in production and measurement technology due to the 75% lower heat input.The design flow developed in parallel for large movement areas is the basis for even more efficient application-specific developments.Together with its partners, IMMS develops and implements precision drives for nanometer-precise positioning in travel ranges of 100 mm and more.By integrating specially developed lifting modules, this is not only possible for planar positioning in the xy plane, but also for movement in the z direction, for example over 10 mm.A newly developed design process forms the basis for the tailor-made and optimized further development of these highly integrated lifting modules, which means that future lifting-load combinations can also be designed more efficiently and quickly.For the redesign of the lifting modules, the underlying planar drive system (Figure 2) was first considered holistically.It is based on a monolithic central body (runner), which can be moved friction-free in the xy plane on three air bearings.Figure 2 Exploded view of the underlying planar propulsion system.(Graphic: IMMS)With the help of four laser interferometers, an autocollimator and plane mirrors integrated into the runner, it is possible to determine its position and orientation in space.Frame-mounted coils generate forces on NdFeB magnets on the underside of the slider, allowing it to be precisely moved in the x and y directions.Additional guides and actuators are now to be installed between the air bearings at the corners and the central body in order to enable a z-stroke of the slider of 10 mm and to be able to eliminate the remaining errors in the tilting angles φx and φy.With this arrangement, the runner only has to be modified minimally and it is possible to use three identical modules, over which the weight to be carried of around 12 kg is evenly distributed.The specifications for a precision system are usually very detailed, because interactions that are negligible in classic mechanical engineering can have a significant impact on the achievable accuracy in the precision area.In order to adequately meet all requirements, a suitable constructive development process is essential.In this case, the design principles from precision technology (separation of functions) are brought into line with those from mechatronics (integration of functions).This applies in particular to the two functional core components: the vertical drive and the vertical guide.The lifting module to be designed should be able to lift 4 kg over 10 mm with nanometer precision and free of stick-slip, for which a space of only around Ø 50 mm × 60 mm is available.Particular attention is paid to the heat generated during operation: this should be minimal, because any heating results in thermal expansion and thus loss of precision.In addition, the drive and guide should be designed in such a way that they can be easily scaled for larger loads and ranges of movement.An analysis of the possible drive principles (pneumatic, piezoelectric, electromagnetic) has shown that none alone is able to adequately meet all requirements.A sensible solution is the modification of the coarse/fine drive principle: A first actuator significantly compensates for the weight force, which means that a second actuator only requires very little force to enable precision positioning.A pneumatic cylinder is particularly suitable for weight force compensation, as it has a high force density, does not introduce any heat into the system locally and can be adjusted to different loads via the pressure.The remaining low but highly dynamic precision forces can then be implemented using an optimally designed electromagnetic actuator.In addition, both actuator principles can be easily adapted to larger strokes and loads.An aerostatic bush guide is particularly suitable as a friction-free guide.This can also be easily integrated into the pneumatic cylinder without making functional compromises.The central development step in the design and dimensioning is the modeling of the actuators.Detailed pneumatic models allow conclusions to be drawn about the static and dynamic behavior as well as the air consumption of the pneumatic cylinder.In this way, the piston-cylinder combination with a friction-free seal could be ideally adapted to the requirements and the existing infrastructure.The electromagnetic actuator has a significantly higher degree of design freedom and is therefore the key for application-specific designs based on it: A wide variety of magnet arrangements can be combined with differently designed back irons and coils.In order to find the ideal drive for the given boundary conditions, 13 topologies were examined in detail using a universal performance parameter.The power-to-power ratio is particularly suitable for precision drives because the drive structures can be evaluated independently of the power stage used and the expected trajectory.The electromagnetic field simulations are embedded in a numerical optimization, which means that the ideal geometry can be found for every topology.The magnetic drive determined in this way has a power-to-power ratio of more than 60 N²/W in an installation space of approximately Ø 50 mm × 40 mm.The associated optimization run and the magnetic field distribution are shown in Figure 3 a/b.Figure 3a Optimization of the actuator geometry for the finally selected drive topology, the dimensions of the magnet and coil (wm, wcw, hm, hb) are determined using an automated optimization algorithm.(Graphic: IMMS)The result of the optimization consists of the dimensions found for the magnet and coil of the electrodynamic actuator, which, in addition to the highest possible power-to-power ratio, are characterized in particular by a homogeneous flux density distribution in the movement area of ​​the coil and thus a constant force generation characteristic, see Figure 3 b.Figure 3b 2D cross-section of the optimal drive geometry found and FEM-based analysis of the associated flux density distribution.(Graphic: IMMS)The coil that best suits the power output stage can then be selected from a subsequent parameter study.Overall, the heat generated was reduced by around 75% compared to the previous lifting module.If necessary, the low remaining power loss can also be transported out of the measuring room by an integrated temperature control system.In addition to the concrete design result, a tried-and-tested method is now also available in order to quickly and efficiently arrive at an optimized design of the lifting module for other lift/load combinations and the associated installation space specifications.Figure 4 shows the developed lifting module.The magnetic drive encloses most of the components in its interior, which means that all drive forces lie exactly on the guide axis and therefore no parasitic tilting loads arise.The disruptive forces caused by dragged lines could be significantly reduced by integrating the components that require a supply line into the rotor-resistant assembly.The first measurement results from a single-axis measurement stand in Figure 5 confirm the design.In the first step, the lifting module was placed on the massive granite stator without pressure or current.Figure 5 (top/blue) position measurement while the module is resting on the base without pressure or current, (top/green) position deviation from the target value in closed-loop operation (with active pneumatic weight force compensation and position control by the magnetic drive);(Bottom/green) Associated falling electrical power in the magnet drive;(Bottom/red) Average value of 54 nW of electrical power required for the positioning process.(Graphic: IMMS)The position noise has a standard deviation of 0.22 nm, which is the theoretical limit.In closed-loop operation (air flow, pneumatic weight force compensation, magnetic drive and controller active), an error of 0.29 nm, which was only slightly larger, was achieved with an average electrical power output of only around 54 nW.The newly developed lifting modules were able to prove that several kilograms can be positioned with nanometer precision in a macroscopic movement range, while only a power loss in the low nanowatt range is emitted into the measuring room.They are therefore an important milestone for industrial use in 6D measurement and nanofabrication systems, which are intended to position objects on complex spatial paths with nanometer and subnanometer accuracy.In addition, the design guidelines that have been developed are currently proving their worth when designing further modules for a stroke of 25 mm and a load of 13 kg.The work was carried out as part of the graduate school "Tip and laser-based 3D-Nanofabrication in extended macroscopic working areas" (GRK 2182), funded by the German Research Foundation (DFG).The text is based on the results of the dissertation "A lifting and operating unit for a planar nanoprecision drive system" by Stephan Gorges (https://www.db-thueringen.de/receive/dbt_mods_00047399).Dr.-Ing.Stephan Gorges is a development engineer for precision drive systems at the IMMS Institute for Microelectronics and Mechatronic Systems non-profit GmbH 98693 Ilmenau stephan.gorges@imms.de www.imms.de Photo: IMMSPöppelmann KAPSTO®: The standard availability of sustainable protective caps and plugs has been expanded enormouslyFrom the drawing-based to the agile item-based BOMCustomized special cables for small batch sizesFind the right encoder for the applicationHow to use DC motors as generatorsTheoretical and experimental determination of the O-ring contact widthPeculiarities of hydrogen embrittlement and standardized test methodsIt depends on the axial playMechanical engineering: Incoming orders continue to declineCookies are also used on this site.We can use it to evaluate page usage in order to display usage-based editorial content and advertising.This is important for us, because our offer is financed by advertising.Use of the site is considered consent to the use of cookies.Further information