Advancements in accuracy decline mechanisms and accuracy retention approaches of CNC machine tools: a review

Computer numerical control (CNC) machine tools, as advanced manufacturing equipment, have been widely used in modern manufacturing. The machining accuracy acting as a main index of performance has long been more concerned by the engineering and academic community. However, in practice, it is more important that the CNC machine tools should have the ability to maintain their original accuracy or keep the accuracy within an acceptable range under complex working conditions after long-term service. This paper presents an overview of the research progress on the accuracy decline mechanism and the accuracy retention approaches of the CNC machine tools. First, the leading theory of accuracy decline and the mechanism of accuracy decline, such as moving components, residual stress and deformation, bolt creep and looseness, interface morphology, and ambient temperature, are described in detail. The accuracy decline is evaluated well. Then, various retention accuracy approaches are comprehensively reviewed, and the evaluation of accuracy retention is introduced. Finally, the challenges and opportunities for industry and academia are discussed, and several principle conclusions are drawn.