Investigation of the Smart Tooling System and Dynamics in Ultraprecision Machining of Freeform Surfaces and its Implementation Perspective

Abstract

The concept of the smart tooling system for ultraprecision machining of freeform surfaces compromises the high intensity of developing adaptable technologies towards innovative holding the workpiece and cutting tool mechanisms. This is in line with the emerging development of smart applications in precision engineering and industrial-scale ultraprecision production. Furthermore, due to rapidly growing requirement for three-dimensional micro and miniature components or products in high precision, the ultraprecision and micromanufacturing are getting increasingly applied in aerospace, automotive, medical engineering, optics, and microelectronics in particular. Over the last decade or so, ultraprecision machining has become a key enabling technology for machining complex freeform surfaced components and products in an industrial scale. From the dynamics point of view, freeform surface with a large depth machining using diamond turning machine can be difficult challenging and in some cases. Despite substantial research and investigation were employed in this field, there are some critical issues remained and needing to be addressed desperately. Nowadays, ultraprecision machining is gradually progressing or maturing over time to meet the full range of requirements for exceptional accuracy and desirable surface quality for freeform surface applications. In current precision engineering, actuation systems for precise positioning and motion control of spindles and direct-drive slideways are profoundly reliant on using rotary and linear encoders. Notwithstanding, in the dynamic machining process, the positioning and control are somehow ‘passive’ and unable to directly monitor and control the tool and workpiece statuses. The machining system is hypothetically rigid, and the cutting dynamics are stable. Nevertheless, machining dynamics and the dynamic synchronization of the cutting tool and workpiece positioning have compelled the challenges on the machining system, which should be carefully considered versus conforming requirements of high productivity for the fulfilment of high precision products in particular. It is also imposing the question in the driving and development of next-generation ultraprecision machining systems operating towards higher or even picoprecision. Overall, this PhD research is focused on the fundamentals and implementation perspectives, as discussed above. In this research work, an innovative dynamic cutting force orientated approach is presented for motion control and positioning in ultraprecision machining of freeform surfaces mainly using either slow tool servo or fast tool servo mode machining techniques. This novel method is developed using seamless integration of cutting forces and machining dynamics with the aid of multi-body dynamics analysis. The positioning and dynamic motion between the workpiece freeform surface and cutting tool are achieved under interfacial interactions at the tooltip and workpiece surface. Necessarily, the interfacial cutting dynamics and physics are the foundation for developing the higher-level of positioning and motion control for the next generation ultraprecision machining system. Thus, the critical interfacial areas were identified and researched accordingly. A novel and dynamics-orientated freeform surface toolpath generation were developed to enable the detection of the dynamic effects of the interfacial cutting forces in the process. Also, an innovative smart chuck for freeform surface workpiece holding was designed and developed to fulfil the requirements of positioning and motion control for next-generation ultraprecision machining systems. The approach is further described using analytical and comparative methodology with an in-depth investigation on employing light material such as MMC material for designing the hydrostatic bearing supported direct-drive slideway. The investigation is supported with simulations and experimental trials for evaluation and validation. The results are auspicious and remarkably promising in overcoming the conventional limitation in positioning and motion control. The research concludes with a further discussion on an extensive application case study using this methodology, and its manufacturing and industrial associations and beyond.