3D printing, that is, additive manufacturing, has solved many major problems in general manufacturing, such as three-dimensional tissue structure, microenvironment control difficulty, product production efficiency and repeatability, etc., improved the manufacturing speed and precision of personalized bone implants, and provided a lot of support for curing patients with bone injuries. The application of 3D printing technology in the medical field is gradually extensive, especially in orthopedics. The purpose of this review is to provide a report on the related achievements of bone implants based on 3D printing technology in recent years, including materials, molding methods, optimization of implant structure and performance, etc., in order to point out the existing shortcomings of 3D printing bone implants, promote the development of all aspects of bone implants, and make a prospect of 4D printing, hoping to provide some reference for the subsequent research of 3D printing bone implants.

High-speed motorized spindle heating will produce thermal error, which is an important factor affecting the machining accuracy of machine tools. The thermal error model of high-speed motorized spindles can compensate for thermal error and improve machining accuracy effectively. In order to confirm the high precision thermal error model, Beetle antennae search algorithm (BAS) is proposed to optimize the thermal error prediction model of motorized spindle based on BP neural network. Through the thermal characteristic experiment, the A02 motorized spindle is used as the research object to obtain the temperature and axial thermal drift data of the motorized spindle at different speeds. Using fuzzy clustering and grey relational analysis to screen temperature-sensitive points. Beetle antennae search algorithm (BAS) is used to optimize the weights and thresholds of the BP neural network. Finally, the BAS-BP thermal error prediction model is established. Compared with BP and GA-BP models, the results show that BAS-BP has higher prediction accuracy than BP and GA-BP models at different speeds. Therefore, the BAS-BP model is suitable for prediction and compensation of spindle thermal error.

Background: 3D printing is a kind of rapid prototyping technology. It is a digital model file-based technology that uses powdered metals, plastics and other bond able materials to construct objects by stacking them layer by layer. In recent years, the use of 3D printed artificial bones for repairing or re-placing damaged bones has been widely used. Therefore, the application of 3d printing technology in the field of orthopedics has attracted more and more attention. Objective: This paper introduces the research status of 3D printing technology in the field of orthope-dics, and discusses the future development direction. Method: Summarize various representative patents related to 3D printing bones all over the world. Results: By summarizing a large number of patents related to 3D printing bones, the research status of printing devices, printing materials, structure optimization and related applications of 3D printing bones are analyzed, and the related problems and development trends of 3D printing bones are dis-cussed. Conclusion: The combination of 3D printed bone materials and the optimization of the artificial bone unit structure will improve the mechanical properties of bone grafts and increase the success rate of transplantation. Bone repair aids and surgical guides will improve the success rate of orthopedic sur-gery and will be more widely used in the future. 3D printing technology is more and more widely used in the field of orthopedics, and there will be more research results in the future.