Key Engineering Materials Vols. 315-316

Abstract: The stress states of the ceramic nozzle in abrasive jet machining (AJM) process are analyzed. Results shown that the maximum stress appears in entrance area of the nozzle and minimum stress in middle area, while the stress of exit area was lower than entrance area and higher than middle area. It can interprets why the entrance and exit area of the nozzle were worn badly. The idea of functionally gradient material (FGM) theory was used to design of ceramic nozzle. The purpose was to reduce the stresses at the entrance and exit area of the nozzle during AJM processes. The physical, composition distribution, and property parameter models of the FGM nozzle were established.

Abstract: ID (inner-diameter) slicing is widely used in cutting ingots currently. In this paper, the deflection (axial vibration) and vibration (radial vibration) signals in different slicing conditions of the silicon wafers were measured online and analyzed. The effects of the vibration signals on the machining accuracy and surface roughness of sliced wafers were investigated based on the measurement and analysis of the surface roughness, warpage and TTV (total thickness vibration) of the sliced wafers. The results show that the changes of surface roughness, warpage and TTV of the sliced wafers exhibit approximately consistence with the changes of the power spectrums of the acquired vibration signals in different working stage of the blade. The vibration and deflection signals can give evidence of the changes in the cutting forces and blade performance during slicing. The power spectrum of the signals is useful for monitoring the blade wear and tension condition and predicting the surface quality and machining accuracy of the sliced wafers.

Abstract: The synthesis of nanocrystalline diamond film on polycrystalline molybdenum substrates was carried out by using of self-made hot filament chemical vapor deposited (HFCVD) system. Positive bias voltage on the grid electrode on top of hot filaments and negative bias voltage on the substrate were applied. High purity and extremely smooth nanocrystalline diamond films were successfully prepared by using the double bias method. Raman, SEM, XRD and AFM results show that the diamond films obtained have grain sizes less than 20nm, nucleation density higher than 1011cm-1. The mechanism of double bias is also discussed in this paper. The positive grid bias increases the active, decomposition and ionization of hydrogen and methane molecules, while negative substrate bias helps positive carbon-containing ions bombard the substrate that leads to the high nucleation density of the diamond film.

Abstract: To improve the quality and efficiency of technical service, shorten the producing cycle of product, a new mode of technical service is presented, which is networked technical service based on the multi-Agent technique, network technique and modern communications technique. The architecture and function of the networked technical service system oriented production-NTSS are researched, and the key technologies including multi-Agent system, virtual assembling oriented the process of production and the assignment and rank of technical service information are studied. The workflow of NTSS is discussed, and base on these theories a prototype system is established, and the security, practicability and high efficiency of NTSS are proved.

Abstract: During high-speed machining, in order to make cutting tools work reliably and obtain ideal machining quality, not only good static characteristics, but also good dynamic characteristics are necessary. In this paper, with the help of the close combination of experimental research and modal parameter identification technique, the dynamic characteristics of the machine tool/cutting tool system were analyzed. Experimental results indicated that studying the effect of the dynamic characteristics on cutting force, machining accuracy and surface roughness could provide theoretical basis for effectively excluding the resonance zone that obviously destroyed machining quality and then optimizing cutting parameters further.

Abstract: In recent work, a creative idea has been proposed by applying the rapid prototyping technology to develop a new diamond-coated blade based on ultraviolet-cured resin bond. The new technology features many advantages such as fast processing speed, low environmental pollution, and low energy consuming. This paper makes an investigation on the adherence and abrasion mechanisms of such diamond blades. The experimental plan is well designed for selection of an optimal prescription of the mixture to achieve good mechanical performance and a manufacturing process is proposed to produce ultraviolet-cured resin bonded diamond coated blades. Practical experiments are carried to test the blade performance and to compare with different tools in incising artificial crystal. Furthermore, this paper also observes how the tensile strength and elastic modulus of ultraviolet-cured resin affect the crevasse and quality of machined edge surfaces.

Abstract: Metal fiber manufactured by the methods nowadays available almost could not meet the new requirements any more due to the increasing demands for its properties as it is used more and more widely. In this paper, cutting by multi-tooth tool, a new method, which can bifurcate chip and simultaneously get many pieces of long stainless steel fiber with high tensile strength, good tenacity and corresponding diameter within 100μm even 50μm, is proposed. Tiny fins which induce crystal growth as nucleation in composites can form regularly at the edge of fiber under certain conditions. The fiber possesses unique advantages if it is used to filled, reinforced and porous materials because of its rough surface, fins, high tensile strength and good tenacity.

Abstract: This paper presents a new magnetic polishing liquid (MPL) produced by mixing sub-micron or micron order abrasive particles into a magnetic compound fluid (MCF) and its fundamental performance in surface finishing. MCF is an intelligent fluid, which is developed by mixing a magnetic fluid (MF) and a Magneto-rheological fluid (MRF) into a solvent, and hence reacting upon magnetic fields. In the present work, seven kinds of kerosene-based MPLs were prepared. The hydrodynamic characteristics of MPLs such as the viscosities under different magnetic fields were investigated. The obtained result indicated that the viscosity increases with the growing of the magnetic field and that the type of MPL affects greatly the viscosity. This phenomenon was discussed by observing the magnetic clusters formed in MPL. It was observed that the magnetic clusters are distributed along the magnetic fluxes. An experimental result indicated that the surface roughness varies with polishing time and gets smallest at a certain value of magnetic field strength.

Abstract: Tool life, surface roughness, and cutting forces have always remained extremely important output parameters of milling process. In this paper an attempt has been presented in order to study the influence of cutter geometry and cutter coating upon these three output parameters. Series of high-speed side milling experiments were done upon hardened AISI 4340 and AISI D2 steels using coated and uncoated carbide cutters. Mechanisms of wear occurring in different tools have been described in the paper using SEM photographs and micro-analysis of the tool surface. The analysis of experimental data shows that the coated carbide cutters having high values of helix angle and small values of rake angle, in the negative range, provide the better optimization of highspeed milling of hardened steels. Results imply that tool geometry and coating are influential upon cutting forces and tool wear but not upon surface quality. Introduction of MQL in the process leads the tool to fail abruptly because of the onset of chipping.

Abstract: A standard twist drill is divided into a series of elementary cutting tools (ECT) along its major cutting edges. The natural power consumed by each ECT during free cutting is calculated on the basis of the theory of shear plane. Through optimization, the actual power consumed and the coefficient of non-free cutting of the major cutting edges subject to the principle of minimum energy are calculated. The results indicate that although the major cutting edges of the standard twist drill are straight lines, their cutting process is not free cutting in full sense of the term.