Research progress in additive–subtractive hybrid manufacturing

Compared with the traditional subtractive and equal manufacturing (SM/EM) computer numerical control (CNC) machining, press working, and casting, additive manufacturing (AM) technology has great advantages in the construction of high-complexity parts. Moreover, its material usage rate is high and the production cycle is short. Therefore, AM is the focus of civil aviation and defense industries, which need high-hardness metal materials and precision machining. However, the thermal history of the AM process affects the geometry of the weld pool, causing the workpiece to fail to meet tolerance requirements. Additionally, large temperature gradients and cooling rate inhomogeneity can also lead to excessive residual stress in the formed parts, which may cause deformation or even fracture of the parts. Factors such as poor dimensional and geometric precision, lower surface quality than that in conventionally formed parts, and poor uniformity of material properties hinder further application of AM. To solve the above problems, the concept of additive and subtractive hybrid manufacturing (ASHM) was developed. Additive and subtractive hybrid manufacturing combines AM with traditional machining and material reduction technology on a single work platform. It involves alternating additive and material reduction operations to improve the surface quality and the geometric and dimensional accuracy of the parts and alleviate residual stress in the parts. According to the different characteristics of an energy source for AM, this paper expounded the technical principle and research progress of ASHM based on arc, laser, and other energy sources and introduced the research progress of the ASHM process. The advantages and disadvantages of the application of this technology in the industrial field were analyzed, and the future development direction of the technology was presented. The ASHM process is expected to become more intelligent, integrated, and standardized in the future.