Researchers at the University of Huddersfield’s Centre for Precision Technologies have been carrying out key research into factors contributing to machine tool inaccuracy. This has led to the development of methods for assessing the capability of machines and the formation of a low-cost electronic compensation system.
The accuracy of machine tools is fundamental to the quality of the products they make. A better understanding of why errors occur and how to minimise them is vital to ensuring higher standards of manufacturing and increased productivity.
These measures can significantly reduce the effects of geometric and thermal errors, producing cost savings from improved quality and factory temperature control. A unique virtual reality machine tool program, VirMach, was created to assist in the measurement, error simulation and installation of compensation systems in industry.
Research began in 1992, funded by the Engineering and Physical Sciences Research Council (EPSRC), to increase the precision of machines and improve the quality of work-pieces. Further EPSRC-funded work developed a real-time compensation system and a PC-based pre-calibrated compensation system for correcting the geometric errors of specific machine tools.
Leading UK employers such as BAE systems and Rolls-Royce, as well as major local employers such as Yorkshire-based Micro Metalsmiths, were among the first beneficiaries of PC-based compensation systems and have continued to use increasingly advanced versions of the technology since 2008. The Centre was selected to be a key contributor to Rolls-Royce’s SAMULET project (Strategic Affordable Manufacturing in the UK with Leading Environmental Technology, 2011-2013), helping to develop rapid calibration strategies for machine tools that can reduce the average calibration time from several days to less than one hour.
Variations in environmental and machine-induced temperature can cause changes of size and distortion of shape of machine tool structures, producing significant errors. The Centre uses a range of equipment including thermal imaging and unique temperature sensing strips to help assess these errors efficiently. A new thermal compensation system has also been created to improve existing systems.
Further research helped to combine geometric and thermal compensation software. With research partners across Europe, this has led to a modular approach to solving the effects of temperature. New research is being carried out to make this approach even more effective by improving the efficiency of the modelling through advanced numerical methods and artificial intelligence.
The use of the Centre’s new methodologies throughout the industry has led to a series of industrial training courses, developed and delivered in collaboration with Machine Tools Technologies Ltd and aimed primarily at maintenance engineers employed in advanced manufacturing. These courses help reinforce collaboration between the Centre and industrial partners and provide high levels of essential training for management and personnel. The Centre became a member of the Manufacturing Technologies Association Technical Committee in 2011, providing further opportunities to shape policy and are actively involved in associated BSI and ISO standards committees.
The University’s Centre for Precision Technologies played a key role in HARCO (Hierarchical and Adaptive Smart Components for precision production systems application). The three-year project officially concluded in 2013 and was backed by €3.9 million from the European Commission Seventh Framework Programme. The research resulted in the production of adaptronic modules incorporating electromechanical, electronic and measuring systems that perform a wide range of tasks. These include active vibration control and interactive structural measurement. The result is the extremely high dynamic characteristics and thermal stability required for high speed precision machining.