Numerical analysis and experimental validation of surface roughness and morphology in honing of Inconel 718 nickel-based superalloy

Honing is an important technology for machining onboard system parts.The parts are usually made of difficult-to-machining materials,e.g.,Inconel 718 superalloy.Honing can improve the finishing accuracy and surface quality.However,the selection of the honing parameters was primarily based on the results of a large number of experiments.Therefore,the establishment of a reliable model is needed to predict the honed surface roughness and morphology,and offers a theoretical direction for the choice of parameters.In the present study,a numerical simulation model was constructed for analysis of the honing process by Python.The oilstone,workpiece surface morphology and motion trajectory were discretized by Python,and the machined surface was obtained by trajectory interference.Firstly,based on the statistical analysis of the surface topography of oilstone,the shape of grains was simplified and the surface topography of oilstone was built accordingly.Then,the initial surface morphology of the workpiece was constructed and the trajectory of grains on the workpiece surface was analyzed,which showed the distribution of the removed material.Meanwhile,the plastic deformation of material was analyzed in the simulation model.The critical depth of three stages of contact between grains and workpiece was calculated by the theoretical formula:scratching,ploughing and cutting.By analyzing the distribution of bulge,the plastic deformation in ploughing and cutting stage was studied.Further,the simulated results of honed surface roughness and morphology were validated and agreed reasonably well with the honing experiment.Finally,the effects of honing process parameters,including grain size,tangential speed,axial speed,radial speed and abrasive volume percentage,on the surface roughness of the workpiece were analyzed by the simulation model.

CBN grain wear and its effects on material removal during grinding of FGH96 powder metallurgy superalloy

Grinding with cubic boron nitride(CBN)superabrasive is a widely used method of machining superalloy in aerospace industries.However,there are some issues,such as poor grinding quality and severe tool wear,in grinding of powder metallurgy superalloy FGH96.In addition,abrasive wheel wear is the significant factor that hinders the further application of CBN abrasive wheels.In this case,the experiment of grinding FGH96 with single CBN abrasive grain using different parameters was carried out.The wear characteristics of CBN abrasive grain were analyzed by experiment and simulation.The material removal behavior affected by CBN abrasive wear was also studied by discussing the pile-up ratio during grinding process.It shows that morphological characteristics of CBN abrasive grain and grinding infeed direction affect the CBN abrasive wear seriously by simulation analysis.Attrition wear,micro break,and macro fracture had an important impact on material removal characteristics.Besides,compared with the single cutting edge,higher pile-up ratio was obtained by multiple cutting edges,which reduced the removal efficiency of the material.Therefore,weakening multiple cutting edge grinding on abrasive grains in the industrial production,such as applying suitable dressing strategy,is an available method to improve the grinding quality and efficiency.

Cutting force and its frequency spectrum characteristics in high speed milling of titanium alloy with a polycrystalline diamond tool

In this paper, a series of experiments were performed by high speed milling of Ti-6.5Al-2Zr-1Mo-1V (TA15) by use of polycrystalline diamond (PCD) tools. The characteristics of high speed machining (HSM) dynamic milling forces were investi- gated. The effects of the parameters of the process, i.e., cutting speed, feed per tooth, and depth of axial cut, on cutting forces were studied. The cutting force signals under different cutting speed conditions and different cutting tool wear stages were analyzed by frequency spectrum analysis. The trend and frequency domain aspects of the dynamic forces were evaluated and discussed. The results indicate that a characteristic frequency in cutting force power spectrum does in fact exist. The amplitudes increase with the increase of cutting speed and tool wear level, which could be applied to the monitoring of the cutting process.

Compressive Strength and Interface Microstructure of PCBN Grains Brazed with High-Frequency Induction Heating Method

In order to prepare monolayer brazed superabrasive wheels, the polycrystalline cubic boron nitride（PCBN）grains were brazed to AISI 1045 steel matrix with Ag–Cu–Ti filler alloy using the high-frequency induction heating technique. The compressive strengths of brazed grains were measured. Morphology, chemical composition and phase component of the brazing resultant around PCBN grain were also characterized. The results show that the maximum compressive strength of brazed grains is obtained in the case of brazing temperature of 965 °C, which does not decrease the original grain strength. Strong joining between Ag–Cu–Ti alloy and PCBN grains is dependent on the brazing resultants,such as TiB_2, TiN and AlTi_3, the formation mechanism of which is also discussed. Under the given experimental conditions, the optimum heating parameters were determined to be current magnitude of 24 A and scanning speed of0.5 mm/s. Finally, the brazing-induced residual tensile stress, which has a great influence on the grain fracture behavior in grinding, was determined through finite element analysis.