Key Engineering Materials Vols. 389-390

Abstract: Conventional coating tools have a high affinity for ductile materials, like aluminum alloy, so cutting chips tend to adhere to cutting edge and work material surface. Therefore, chipping is caused, and surface texture is degraded. In order to solve these problems, recently, DLC (Diamond-Like-Carbon) has been applied to coating material. In this research, it is curried out cutting of Aluminum alloy by the use of DLC coating tool, and examined influence of DLC coating conditions on cutting characteristics. So far we have been concerned with the effect of type of hydrocarbon gas (acethylene:C2H2, methane:CH4) on cutting. As a result, it is revealed that cohesion of chips decreases, and surface roughness of work material improves in the case of acethylene-DLC. On the other hand, internal stress is produced by deference in hardness between tool surface and DLC film, and which is considered cause of film peeling [1]. Therefore, we examined interlayer between DLC film and tool surface in order to relax of internal stress. As a result, it was cleared that Titanium interlayer excels in adhesion.

Abstract: In this paper, orthogonal cutting tests of alloy steel, aluminum alloy and Ti6Al4V have been carried out to consider the cutting mechanism from the viewpoint of friction between the tool and workpiece. The cutting processes were observed in detail using a high-speed video camera. The cutting process of alloy steel was greatly affected by its tribological properties compared with those of the other two work materials. In the cutting process of alloy steel, there were three stages in relation to the state of the tool rake face and temperature. The difference between non coated and coated tools was marked in the later stages. From the discussion on the experimental results, it is considered that the thrust force is suitable for representing the tribological properties between the tool and workpiece. It is concluded that the orthogonal cutting test is a good method for evaluating tribological properties between the tool and workpiece.

Abstract: Large amount of cutting oil consumption is one of the issues for environment. The Minimum Quantity Lubrication (MQL) technique has been applied to the near-dry cutting process. However, MQL technique generates oil mist which is harmful to the working environment and the health of factory workers. In this study, a new lubrication system called Direct Oil Shot Lubrication System (DOS) was developed and applied to milling processes. The performances of DOS technique was evaluated by measuring the floating oil mist and carrying out the cutting tests. The amount of floating oil mist of DOS system was considerably reduced compared to the MQL. The behavior of small oil drops supplied from DOS nozzle to cutting edge was analyzed by means of a high speed video observation, and the optimum setting for DOS was obtained. The experimental result shows developed DOS system realized the smaller density of oil mist floating than the MQL technique while the DOS attained the almost same lubrication effect in milling process as the MQL technique.

Abstract: The paper presents a newly developed optical polishing method, Ultrasonic-magnetorheological compound finishing (UMC finishing). The mechanism of UMC finishing is introduced in the paper. Experiments are carried out to study the surface quality of the optical glass K9 in UMC finishing. The result shows that the surface roughness Ra of the optical glass is 4.0nm, which is measured by the profile meter. The rules of surface roughness for optical glass by the main processing parameters are also acquired by the experiments. The study will be the basis for the further study of UMC finishing technology.

Abstract: This paper deals with the machining of quartz wafers using an MCF (Magnetic Compound Fluid) polishing liquid, frozen with liquid nitrogen. This type of polishing liquid is composed of water-based MF (Magnetic Fluid), iron powder, abrasive particle and α-cellulose, and consequently reacting to magnetic fields. Experiments of polishing quartz wafers using the MCF method were carried out on a previously developed apparatus. The results show that an MCF polishing liquid, frozen with liquid nitrogen, has greater material removal capability than one that has not been frozen. A frozen MCF polishing liquid containing larger abrasive particles yields a higher material removal rate, however the surface roughness deteriorates. The highest material removal rate and the best surface roughness were obtained when the percentage of water, in the frozen MCF polishing tool, was 34.7%.

Abstract: At first, a relative mathematical model for electromagnetic inductor was constructed. On the basis of electromagnetic calculation theory, simulation analysis of magnetic field of electromagnetic inductor was performed with finite element method. Then, the magnetic flux density of the actual electromagnetic inductor was measured. Simulation result is basically identical with experimental result, and the maximum relative error is not more than 7%. It proves the validity of simulation analysis of the electromagnetic inductor. Based on the above results, the experiments of the Magnetic Abrasive Finishing were performed. The results offer a theoretical foundation for the magnetic abrasive finishing experiment and the optimum design of the electromagnetic inductor.

Abstract: In this paper, a new kind of NC magnetic abrasive finishing method with meshy polishing track to grind the parting face of mould was presented, and a new simple polishing tool using permanent magnet was also developed. Using the magnetic polishing tool, 3D NC polishing experiments was conducted on 2D parting surfaces. Experimental results reveal the relationship between several main parameters (rotational speed of magnetic pole, working gap, feeding speed and number of polishing times) and surface roughness. This study is expected to be helpful to improve the efficiency of finishing process, reduce worker's labor intensity, realize the effective control of finishing process and obtain fine quality of workpiece surface.

Abstract: In this paper, a Drill Point Simulation System (DPSS) which is being developed at Northeastern University is presented. By means of DPSS, the geometric models of the helical drill points were shown after inputting their design parameters. Then, the grinding parameters of the helical drill points were produced. According to the grinding parameters, the helical drill points were ground by the SD helical drill point grinder which was developed at Northeastern University. Furthermore, drilling tests were performed on aluminum sheet workpieces to investigate drilling performance of the helical drill points. In addition, the relationships between the geometric parameters of helical drill points and their grinding parameters also were derived.

Abstract: The use of cubic boron nitride (CBN) over conventional abrasives in ferrous and superalloy grinding has resulted in improved manufacturing throughput and beneficial mechanical properties on workpiece surfaces. However, through the innovative use of crystal synthesis techniques, the grinding performance can be further improved over existing CBN crystals. In this study, such a new CBN crystal is developed, characterized, and its grinding performance is compared to a commercially available CBN crystal. Grinding tests are conducted in AISI M2 steel and Inconel-718 superalloy using a vitrified bond configuration with applicability in a wide range of end-use applications.

Abstract: This paper investigates two kinds of grinding wheels prepared by the combination of mechanical alloy and hot-press sintering (MA-HPS). Scanning electro microscopy, Optical microscope, Talysurf surface profiler, X-Ray diffraction and Raman spectroscopy were used to characterize two kinds of grinding wheels and identify the removal mechanism. It was found that FeNiCr matrix-TiC (FMT) grinding wheel yielded higher removal rate than TiAl abrasiveless carbophile (TAC) grinding wheel, which conversely owned good polishing quality; diamond was removed by transformation diamond to non-diamond carbons and then removed by mechanically or diffusion to grinding wheel during polishing process with FMT grinding wheel. While TAC grinding wheel polishing CVD diamond film mainly depended on the reaction between diamond carbon and titanium.