The difficult-to-machine materials (e.g. titanium alloys, superalloys, intermetallics and high-strength steels, etc) have attracted increasing attentions in manufacturing the key components in aerospace fields in recent years, resulting from their superior mechanical properties. Grinding, as the final machining method, has been employed to fabricate those materials and the associated key components, playing an important influence in the manufacturing quality and efficiency. However, there are problems such as large grinding force and temperature, severe wear of wheels, and poor grinding quality, owing to the difficult machining property of those materials and the complexity of grinding processes. This paper summarized the research progresses and existed problems in view of the grinding force, the grinding temperature, the wheel wear and the ground surface quality. The research object was the difficult-to-machine materials in aerospace fields and the main discussion topics focused on the simulation during grinding processes and intelligent control techniques. Finally, the future development trends of grinding process simulation and intelligent control technology were prospected regarding the main problems existing in current researches.

The hot-pressing sintering experiments were carried out under the conditions of sintering temperature of 950 ℃, holding time of 5 mins and different sintering pressures. The effects of sintering pressure on the properties of three kinds of low liquid phase Fe-based pre-alloyed bit matrix and one traditional Fe-based bit matrix were compared and studied, including the hardness, the bending strength, the relative density, the diamond embedding strength of the matrix, the thermal damage of diamond. as well as the microstructure and the morphology of drill bit matrix. The results show that with the increase of sintering pressure, the indentation hardness, the bending strength and the relative density of blank matrix with low liquid phase gradually increase, but the hardness and the bending strength of traditional Fe-based pre-alloyed blank matrix increase at first and then decrease, and the relative density increases. For the matrix containing diamonds, the bending strength of low liquid phase and traditional Fe-based matrix increases with the increase of sintering pressure. When the sintering pressure is 20 MPa, the bending strength of the diamond containing matrix with low liquid phase tends to be stable, while the bending strength of the traditional Fe-based matrix containing diamond decreases slightly. At the same time, with the increase of sintering pressure, the homogeneity of the low liquid phase matrix is enhanced, but the thermal damage of the diamond is gradually aggravated. According to the analysis of the mechanical properties and the fracture morphology of the matrix, the optimal sintering pressure is 20MPa. At this time, the hardness and the bending strength of the low liquid phase Fe-based pre-alloy matrix can meet the requirements of impregnated diamond bits.

The fused deposition modeling sintering (FDMS) technology has developed rapidly in recent years and has a great potential for development in the manufacture of diamond tools because of its advantages of low energy consumption, high printing stability, low cost of forming equipment and simple operation. The technical feasibility of preparing diamond tools by FDMS technology is analyzed. The preparation process flow, the printing parameter optimization and the printing equipment optimization design of FDMS technology are systematically discussed. The research results of manufacturing diamond ultra-thin blades by FDMS are listed. The key problems of FDMS technology in manufacturing diamond tools are pointed out, and its development is prospected.

In order to solve the problem of thermal deformation of brazed saw blade substrate under high temperature, the temperature, the microstructure and the stress-strain field of local induction brazed saw blade substrate were analyzed with the finite element software, and the factors affecting the deformation of saw blade substrate were studied. The results show that the phase transformation of the saw blade substrate is mainly distributed on the brazing working surface. After cooling to room temperature, three microstructures including ferrite, pearlite, bainite and trace martensite are obtained. When the scanning speed of the heat source increases, the deformation and the residual stress of the substrate increase. When the scanning speed increases from 0.25 mm/s to 2.00 mm/s, the thickness of the phase change layer decreases from 5.8 mm to 4.7 mm, the maximum deformation increases from 0.41 mm to 0.82 mm, and the residual stress increases from 482 MPa to 667 MPa. The test results are basically consistent with the simulation results.