Community Research and Development Information Service - CORDIS

Periodic Report Summary 1 - OPTEMUS (Optimising Turbo-Spindle Efficiency for Machining at Ultra-High Speed)

Reducing energy demand in industry is a critical aspect of meeting global CO2 emission reduction targets. For the production of micro-sized parts and features, the miniaturisation of machine tools that produce such parts offer significant energy savings. In this project, OpTEMUS, we investigate the optimisation of efficiency for Ultra-High Speed Spindles, a key component of precision machine tools. Current commercial micro-machining spindles suffer from very low energy efficiency, which leads to increased costs and environmental impact. The challenge is to increase efficiency while maintaining small size, rotational accuracy and economic viability. To investigate and address these issues, this project aims to develop and demonstrate a high efficiency turbine spindle.
To date, the research efforts have focused on designing a new radial inflow turbine stage (rotor, nozzle guide vanes and volute) for the spindle, and developing an experimental setup to measure spindle torque and power output. Currently, the measurement of torque and power output of high speed spindles is prohibitively expensive with existing commercial dynamometer systems. An alternative measurement technique, using a flywheel of known inertia, was therefore developed and tested on a commercial hand-held grinder. The tests confirmed the low efficiency of commercial spindles, with a maximum exergy efficiency for the unit of less than 20%. The goal for the OpTEMUS spindle is to achieve an overall spindle efficiency greater than 60% (including bearing losses).
Computational Fluid Dynamic (CFD) simulations of the initial baseline turbine design indicated that a total-total isentropic efficiency of around 70% is achievable, using a radial inflow turbine with fully 3D geometric blade shape. Multiple revisions to the turbine design have preserved this level of efficiency while further decreasing size, weight, inertia, and thrust forces generated by the rotor. Additional efforts are ongoing to minimise the unbalance forces acting on the turbine, a critical determinant of shaft lateral vibration amplitude and dynamic spindle runout. The final design of the overall spindle is also nearing completion. The maximum speed of the spindle will be approximately 130,000 rpm, with a nominal power output of 120W at design conditions. The remainder of the project will focus on the physical prototype development to validate the simulation performance predictions, and provide data and feedback for future turbine-spindle designs. Ultimately, it is hoped the project results (in the form of a miniature spindle prototype) will spur the adoption and commercialisation of high efficiency radial turbines in micro-machining spindle technology. A grant proposal is planned to allow for knowledge transfer to a European based spindle/turbine manufacturer, following completion of the Fellowship.


Aveen Lavery, (EC Research Support Officer)
Tel.: +44 2890 975360
Fax: +44 2890 975182


Life Sciences
Record Number: 187625 / Last updated on: 2016-08-22
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