Advanced Materials Research Vols. 69-70

Abstract: This paper describes an atomic force microscope (AFM) based instrument for 3D edge profile measurement of single-point diamond cutting tools. The instrument is composed of an AFM unit and an optical sensor for alignment of the AFM probe tip (silicon cantilever) with the diamond cutting tool edge. In the optical sensor, a laser beam from a laser diode along the Y-axis is focused to generate a small beam spot with a micrometer-order diameter at the beam waist, and then received by a photo-detector (photodiode). The tool edge top and the AFM probe tip are brought to the center of the beam waist in the XZ-plane through monitoring the variation of the photodiode output, respectively. Consequently, the AFM tip can be aligned with the tool edge top. Alignment experiments and 3D edge profile measurements of a round-nose type single-point diamond tool are carried out.

Abstract: This paper proposes a new magnetic field assisted machining process using a magnetic machining jig (permanent magnet tool) to finish the internal surface of thick tubing 5~30 mm in thickness. Because the magnetic machining jig consists of permanent magnets, it can generate a higher magnetic force (finishing force) than conventional magnetic abrasives, and makes possible the internal finishing of thick non-ferromagnetic tubing. First, the principle and the feature of this process were examined. It was compared that the difference of the mechanism of using the conventional magnetic abrasives and magnetic machining jig (magnet tool) was clarified. Next, a processing unit and magnetic machining jig were made, and the processing unit was set on a lathe machine. An experiment was performed on a thick SUS304 stainless steel tubing 5 mm in thickness. In this study, it was clarified that this processing method can improve the roundness of the inside tubing while improving the surface roughness. The results showed that the initial surface roughness of 6.5 μm Ra can be improved to 0.06 μm Ra, and the roundness of the inside tubing can be improved from 187 μm to 89 μm.

Abstract: Ultrasonic machining (USM) is an effective machining method for hard brittle materials. In the USM process, the slurry is supplied to the gap between the ultrasonic vibrating tool and the workpiece. Materials are removed by the accumulation of small brittle fractures made by the impacts of abrasive grains. In a previous study, we proposed electrorheological fluid (ER fluid) assisted-USM, and the effect of ER fluid-assisted USM was confirmed practically by machining precise micro-holes and micro-grooves on hard brittle materials. In the present paper, in order to confirm the effect of ER fluid assistance for micro USM in more detail, the behavior of abrasive grains in the machining area is observed. The effect of dielectrophoretic force acts on the abrasive grains and the effect of using ER fluid assistance are investigated. As a result, the abrasive grains can closely approach the micro tool by the effect of dielectrophoretic force and be fixed around the micro tool by the effect of ER fluid assistance. Under these conditions, the workpiece is removed primarily by the accumulation of small brittle fractures, and the chipping can be reduced.

Abstract: MoS2/Zr composite coatings were deposited onto M2 high speed steel tools by medium-frequency magnetron sputtered coupled with multi-arc ion plated techniques. The thickness, micro-hardness and coating-substrate adhesion strength of the coatings were studied. Surface morphologies of the as-deposited coatings as well as wear surface features after dry machining tests were investigated. The experimental results indicated that deposition of PVD MoS2/Zr composite coatings onto M2 HSS tools shows higher hardness compared to the pure MoS2 coatings, and exhibits significant enhancement in cutting performance. The wear mechanism of the MoS2/Zr coated tools is mainly delamination of the coating owing to the elevated cutting temperature and friction force.

Abstract: In this paper, it is explored the material removal mechanism in vibration-assisted finishing process. On the basis of some experiments, the finishing characteristics are represented summarily. Though the analysis, it is shown that the vibration assistance method may increase cutting distance and speed of abrasive and material removal in per unit finishing distance which is affected by vibration frequency and amplitude, in-process abrasives behavior. What more, the increase in material removal rate is mainly due to an increase in material removal per unit finishing distance which is affected by the effects of abrasives cross-cutting.

Abstract: PCBN cutting tool’s wear in high speed precision reaches tool wear criterion will cause cutting force and cutting temperature increase clearly, chip color change or melt. Even vibration in cutting will influence dimension accuracy and surface quality of workpiece. It is very useful to establish model by FEM simulation of tool wear predicted. The influence of tool wear in cutting conditions will assurance of machining quality and efficiency, decreasing rate of product cost. PCBN cutting tool’s wear is simulated by FEM software Deform 2D, rake face wear state can be analysed by the influence of tools geometric parameters and cutting parameters tool wear.

Abstract: Based on experimental results, a predictive model with certain constraints of cutting parameters (feed rate and depth of cut) and nose radius for cutting forces is solved in precision turning 3J33 alloy. The proposed model is adequate with F-ratio test and multiple correlation coefficient of it. Regression analysis shows that depth of cut and feed rate influence the principal cutting force significantly. The goal of this study is to predict cutting forces under certain constraints of cutting parameters and nose radius.

Abstract: Ceramics are increasingly used in many advanced science and technology due to their excellent properties. Grinding is the most efficient and effective technique to achieve high dimensional accuracy and surface integrity of ground ceramic workpiece at optimum cost efficiency. The indentation/ scratch approaches are widely used in studying the grinding process. In this paper, the grinding technology and grinding induced damage of advanced ceramics are briefly reviewed. Based on MSC.Marc software, a FEM model for the Vicker’s indentation/scratch is established to simulate the abrasive grinding process, the stress and strain distribution in the advanced ceramics under a Vicker’s indenter are presented and discussed. The related elastic modulus is obtained by the nanoindentation tests.

Abstract: Based on the principle of micro electrical discharge machining (EDM), a reversible machining method is proposed, which can achieve depositing or removing selectively metal material for the fabrication of micro structures. It is easy to transform the machining process from deposition to removal in one machining system. The characteristics of the deposited material show that the components of deposited material are almost the same as those of the tool electrode, and the metallurgical bonding has formed on the interface between the deposited material and the base. Moreover, the deposited material has well machinability in different micro EDM selective removal process, including micro EDM die-sinking and micro EDM milling. As a result, a micro square column with 0.1mm in side length, 0.88mm in height and a micro cylinder with 0.14mm in diameter, 1.18mm in height were fabricated by using the micro reversible EDM process.

Abstract: The micro abrasive jet machining is used to make the microfluidic channels on the glass substrate. Based on the tests with or without masks, the structure profile and erosion rate with different basic machining parameters, such as nozzle standoff distance, scanning speed, abrasive mass flow rate etc. are investigated. The optimum parameters for micro-structure machining of glass is discussed. The effect of the secondary rebounding particles in mask underetching was analyzed using oblique machining. And the flux effect was also studied comparing with the unmasked machining.