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PRODUCTS MOTION CONTROL A SIX-AXIS PRECISION MOTION SYSTEM MOTORISED LEAD SCREWS


A PC controlled ‘Two Crystal Characterisation Positioning System’ has been developed by LG Motion for AWE Aldermaston. This 6-axis vacuum-compatible precision motion system is being used to determine properties of x-ray diffraction crystals prior to installation into x-ray sensitive diagnostics for fielding on laser plasma experiments. The system features three stepper motor driven rotary tables and a 350mm travel stepper driven linear axis. These combine to support optical diffraction mounts and sensors, with two 35mm travel manually adjustable linear stages used to pre-position static optical equipment. The rotary and linear stages were vacuum modified standard tables from LG


Motion’s LG series – part of a wide range of standard linear, rotary and elevation stages that are available with stepper or servo motors to form complete multi-axis positioning solutions. The specification for the positioning mechanics called for <0.075mm for the linear stage and <0.1˚ for the rotary tables, whilst repeatability was <0.02mm and <0.05˚. Operator and supervisor level access to set-up and calibrate the optical system,


and to load and run coded pre-defined characterisation routines that run across the PC and the motion controller, is provided by LG Motion’s pre-programmed user interface. A control cabinet houses the motion controller and stepper motor drives, and all positioning mechanics are mounted on an aluminium baseplate. AWE integrated the mechanics into the vacuum chamber with connections through their vacuum bulkhead to the cabinet via 5m cables. The scope of supply also included 10-6


vacuum preparation with special lubrication and holes to avoid any possibility


of cavities forming under vacuum. All motorised axes used vacuum compatible micro-stepping motors from LG Motion’s distribution partner, Empire Magnetics.


LG Motion T: 01256 365600 www.lg-motion.co.uk A PLANAR AIR-BEARING PLATFORM


According to Aerotech, its new PlanarHDX is the most


advanced commercially available planar air-bearing


platform available. Its structural elements were


designed using an advanced silicon carbide ceramic with a specific stiffness (elastic modulus/density)


five times higher than aluminium and a coefficient of thermal expansion approximately five times lower. The resulting structure enables 1.5m/s scan speeds and 5g peak acceleration with a payload of up to 20kg. Other design enhancements include a new air-bearing


compensation strategy that increases stiffness and load capacity. A proprietary reaction-mass design reduces stage-induced forces in the step-axis that are transferred to the isolation system or customer’s structure. By minimizing these dynamic forces, move-and-settle time is reduced and process throughput is increased. The PlanarHDX


is available


with passive or active isolation systems; and additional axes such as Z-tip-tilt or Z-theta designs, as well as custom wafer load/unload mechanisms and wafer chucks, are available. Advanced control features are available; and Aerotech’s


ETM (Enhanced Throughput Module) option helps improve the positioning performance of high-dynamic motion systems, the company explains.


Aerotech www.aerotech.com Enter 224 Enter 222


New from Thomson Industries is a range of Motorised Lead Screws that combine a hybrid stepper motor and lead screw in one compact envelope. According to the company, optimised motor performance matched with ideal screw and nut design produces a higher performing product with reduced power consumption, low noise and longer battery life. In addition, the cooler running motors mean greater torque can be generated using higher power input without overheating. These also feature the company’s Taper Lock technology which enables quick connection/decoupling of the lead screw and the stepper motor. The Motorised Lead Screws are available in two motor


configurations: Rotating Screw (S) and Rotating Nut (N). They come in standard and high precision variants and have a wide range of options. NEMA frame sizes between 11 and 23 can be selected with various lead screws available in metric and imperial sizes. Stepper resolutions range from 0.005mm to 0.1mm and the NEMA 23 variant delivers a maximum axial thrust of up to 890N. Motorised Lead Screws are suitable for linear motion


applications where precision, reliability and greater design flexibility are advantageous. Their quiet, smooth and clean operation enables their use in the medical market; and the Rotating Screw (S) lead screw is suitable for applications that require precise linear motion with external supports, such as medical devices and 3D printers. The Rotating Nut (N) lead screw serves applications that also require precise linear motion but that have integrated anti-rotation, including medical pumps, HVAC control valves, etc.


Thomson www.thomsonlinear.com Enter 223 DRIVES IMPROVE GLASS QUALITY


From its base in New Jersey, Glaston America manufactures glass tempering ovens, and to ensure these meet the demanding requirements of high profile customers, every effort is made to maximize quality. Recently, for example, the company had to address the issue of the tiny scratches that can occur as a result of the glass being tempered without precise speed control on the oven’s drives. The solution was found in Control Techniques’ Unidrive M701, due to its new features and functionality, and the integration of PROFIBUS communications and application modules. In addition, each Unidrive M model suits specific application needs – the Unidrive M701 series drives, for example, offer benefits specific to sectors such as ovens and heat treatment equipment. 14 of the drives with SI-PROFIBUS are now deployed in the glass tempering


ovens, one for each roll section. Rollers pass glass through various oven sections to be treated and then through a cooling section prior to packaging. Glaston also uses 14 Unimotor HD, highly dynamic brushless servo motors, one for each drive. Cliff Matukonis from Glaston said: “The main benefit of the Unidrive M701 is the precise speed control we can now exert on the oven rolls, which greatly reduces scratches and imperfections on the glass.” In addition, the system’s design and


interfaces, along with its extensive diagnostics capability, ensure ease of use. The Unidrive M family offers induction and permanent magnet servo motor performance with real-time Ethernet. Each


drive delivers maximum machine throughput through greater control with single and multi-axis network synchronization. These also have on-board real-time Ethernet (IEEE 1588 V2), advanced motion control and high speed I/O for position capture.


Control Techniques 24 MAY 2015 | DESIGN SOLUTIONS www.ControlTechniques.com Enter 225 / DESIGNSOLUTIONS


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