Planar double-enveloping hourglass worm drive has attracted much attention due to its high performance. It is widely used in modern industrial fields and conforms to the development trend of gear technology. This paper deeply discusses its design and machining. In terms of design technology, the mathematical model construction is summarized, and it is pointed out that the meshing performance can be significantly improved by optimizing the worm parameters and tooth surface modification. At the level of machining technology, advanced processes such as CNC turning, virtual rotary center technology, five-axis linkage machining, rotary cutting and four-axis machining are comparative analysis. It is emphasized that these technologies play an important role in improving machining efficiency and accuracy and reducing costs, and it is pointed out that there is still room for further improvement. Finally, this paper looks forward to the design and machining of the planar double-enveloping hourglass worm, and puts forward suggestions for future research directions.

Micro-milling as a precision manufacturing process has received increasing attention for its unique advantages in machining tiny parts. The surface quality of parts is an important factor that affects the performance and life of micro parts. Therefore, the study of the surface quality of parts after micro-milling has become an important topic of great interest. In this paper, the surface roughness generation models are reviewed to provide a comprehensive understanding of the various factors affecting surface quality. Based on these models, the key factors affecting surface roughness and burr generation are summarized. Furthermore, the challenges and opportunities for achieving high surface quality parts during micro-milling are summarized and some suggestions for future research are expected.