LG Motion Ltd has recently supplied a three-axis XYZ gantry positioning and motion control system to the University of Oxford’s Department of Materials (Oxford Materials) for a very interesting research project using innovative spray deposition to manufacture thin and think film energy storage electrodes and devices, with the aim to demonstrate potential benefits of this approach over existing manufacturing routes. The work is part of research that looks to develop new processing technologies that offer the potential for cost-effective scaling to the near-industrial, and then full industrial use.
The spray deposition approach is based on atomising nano/micro-suspensions into droplet streams using compressed air that are sprayed onto heated current collectors where the electrodes are formed. It is a flexible approach demonstrated at small scale for many different energy storage materials, and offers some flexibility in designing electrode structures for improved performance. Later in 2014, Oxford Materials is installing larger-scale spray processing capability to complement the LG Motion rig, to investigate additional applications for the technology in collaboration with range of UK and overseas companies.
For this particular application, LG Motion was asked to provide a cost-competitive mechanical positioning and motion control system that would enable a scanned area of 300mm × 300mm in the horizontal plane with a vertical axis to position the spray head over 200mm. The research project, ‘Spray processed electrodes in new materials for energy storage applications’ is led by Professor Patrick Grant and explores layer-by-layer spray forming of electrodes for use as electrochemical ‘supercapacitors’ for future energy storage devices for mobile phones, computers and other devices that are increasingly required to be lighter, smaller and provide longer life than current technologies.
The gantry system specification called for relatively low speeds, low duty cycle and medium precision to perform the required scanning with a load of up to 3kg. To keep costs to a reasonable level an open loop stepper motor based positioning system, centred on LG Motion’s XSlide range of leadscrew driven linear positioning stages with NEMA size 17 high torque motors, was used. This compact and low-cost positioning system is well proven in medium-precision applications across manufacturing production, test and research, and is easily adapted for travel length and configuration in custom engineered multi-axis set-ups.
Easy and adaptable assembly
Mounted on a machine frame fashioned from MiniTec’s Profile System, the gantry consists of a single XSlide stage to one side with its moving carriage coupled to linear bearing guide and carriage on the other side of the gantry. These carriages together support the Y-axis XSlide with the Z-axis vertical stage simply mounted via an angle bracket. Throughout the mechanical set-up, standard bracketry and modular mounting make assembly easy and adaptable. The stepper motors are fitted with hand wheels to aid manual positioning and over-travel limit and datum switches ensure safe operation under full control. The mechanical system also includes a cable management system which is easily supported within the design using the MiniTec machine frame.
Adaptability was also a key factor for the motion control system, and LG Motion specified its Arcus Technology range of cost-competitive stepper motor controls for the job. The PMX-4ET-SA is an advanced 4-axis motion controller and stepper drive with 10Mbps Ethernet communication that provides advanced features only found on more expensive motion controls. With linear and circular axis interpolation and with fast synchronising inputs and outputs, the controller provides up to a 6MHz step and direction pulse rate which suits smooth and fine resolution microstepping combined with the coordination of motion and external events required for the application.
The Arcus PMX series allows the easy and straightforward programming of a scan area with predetermined firing of outputs to synchronise the spray deposition process. This can be achieved via Ethernet using simple BASIC like programming commands and a terminal facility supplied with the controller. LG Motion also provided a simple GUI front-end program to handle this requirement, and alternatively the controller is able to process motion and I/O commands from a PC using free of charge source code for Windows programming languages such as Visual C++ and Visual Basic, .NET as well as LabVIEW. This programming flexibility will allow Oxford Materials to adapt the system as the research project progresses. The PMX also has the ability to include encoder feedback with a novel closed loop algorithm that allows position verification should they wish to increase the system repeatability in the future.
LG Motion worked closely with Oxford Materials during all phases of the project and delivered the complete system, pre-wired and fully tested for use on the project. Please visit www.lg-motion.co.uk to learn more about the three-axis XYZ gantry positioning and motion control system.