Impact micro-forming technology: Current status, challenges and prospects

Micro-forming is a very promising technology to manufacture micro parts and components for its advantages of high efficiency, low cost, and excellent mechanical performance of the products. But the increasing in friction, decreasing in formability and accuracy, difficulties in stroke controlling and the alignment of dies in micro-forming limit its development. Impact micro-forming, belonging to high strain rate forming and punch-less process, has the potential to improve material formability, reduce friction, and overcome the difficulties of die alignment and stroke controlling in micro-forming. In this paper, a classification of impact micro-forming processes is orchestrated and presented, and three kinds of impact micro-forming technologies, viz., laser shock micro-forming, electromagnetic micro-forming, and water-jet micro-forming, are reviewed and delineated as they are currently receiving a widespread attention with promising application potentials. The fundamental principle, setup and equipment utilized in these three impact micro-forming processes are firstly introduced, respectively. Then the effects of process parameters on the forming performance in different applications are systematically recapitulated, and some new emerging technologies and some newly established innovation in the process are exemplified and discussed. In addition, some challenges faced by these three impact micro-forming technologies are summed up. Finally, an overall summary and outlook about the impact micro-forming technology are presented. This work has important reference value and guiding significance for researchers to further understand the theory, parameter selection and innovation developed in impact micro-forming technology.