Key Engineering Materials Vols. 407-408

Abstract: There are different opinions on whether the tool life could be improved by the vibration drilling or not. The factors which affect the drill life during micro hole drilling were analysed, and the vibration drilling has the effective region characteristic for drill life. That is to say, the vibration drilling can extend the tool life significantly within the certain range of the hole depth (or depth-diameter ratio). The stainless micro hole drilling experiments were done, and the results showed that the life advantage for vibration drilling was represented on certain region, that is effective region phenomenon

Abstract: Different thickening agents are added into the prepared water-based working fluid for electrical discharge machining (EDM), and the influence on the process performance is investigated in this paper. The experimental results demonstrate that the proper addition of polyvinyl alcohol (PVA) and coconut diethanol amide (CDEA) can increase the material removal rate of EDM, advance the electrical conductivity of the working fluid and enlarge the discharge gap, but has a little influence on the relative electrode wear ratio. Moreover, the material removal rate can increase 1.1 times and 1.3 times with proper addition of PVA and CDEA respectively in comparison with no thickening agent, and the addition of CDEA promotes better EDM performance

Abstract: On the basis of analysis of disadvantage to conventional pulse generator, a kind of new Energy-Saving EDM pulse generator is developed to machine non-conductive ceramics in this paper. The pulse generator is provided with function of self-adapting voltage-adjusting Al2O3 ceramics is machined to use the generator by EDM assistant electrode synchronization servo machine tool. Results indicate the pulse generator can availably improve the energy availability and discharging efficiency

Abstract: The purpose of this study is to develop the cavitation aided abrasive machining which makes effective use of cavitation occurring in suction flow of slurry for fine machining. In this paper, a fundamental machining phenomenon of glass using the cavitation suction flow is clarified and machining characteristics are experimentally investigated by the observation of machined surface and surface roughness, stock removal and cavitation impact. Abrasive grains impinge on a workpiece surface to physically remove work material and generate fine surface in the machining. Then it can finish the polished glass surface of 9.3nmRz down to about 5.0nmRz by using abrasives of WA 4000.

Abstract: A new finishing technology of the swirling airflow compounded with magnetic-field is advanced. Machining prediction is carried through by simulating magnetic field and flow field. Abrasive velocity and grinding pressure according to injection pressure and abrasive diameter are shown. Unthreaded hole is experimented on the condition of adding magnetic field or not and the decrease of surface roughness on eight sampling points along axis is obtained. Research indicates that the swirling airflow compounded with magnetic-field finishing is feasible from the simulation and Adding magnetic field may avoid the ununiformity of finishing as well as increase finishing effect.

Abstract: EDM; Gap voltage/current; Wavelet analysis; Modulus maxima algorithm Abstract: According to the characteristics of Electrical Discharge Machining Gaps Signal for Non-conductive Engineering Ceramics, the wavelet modulus maxima algroithm was uesed to denoise the gaps voltage/current signal. Compaered the differernt denoising result of different wavelet function, Maxihat wavelet, Meyer wavelet, Daubechies wavelet and Gaussian wavelet, the fitting wavelet function, Gaussian wavelet which used to denoising the EDM Gaps voltage/current signal was found out, and the fitting scales space [-5,+1] and the normalized threshold value interval [0.1,0.3] was determined.

Abstract: . Electrochemical drilling (ECD) is a versatile process for drilling meso/micro size holes in hard-to-machine metals. Electrode insulation plays a significant part in improving ECD localization and accuracy. Electric field simulation of the side gap shows the current distribution varies remarkably with the size of insulation layer shape. Experiments are carried out to study the influence of insulation thickness (IT) on the machined hole characteristics. Poor hole was observed and identified as most likely to occur with a combination of low tool feed rate and low IT. Electrodes with the relatively thick insulating layer leads to a significant improvement in bored hole precision.

Abstract: . Burr is formed at workpiece edge in most metal cutting process. These burrs make troubles on production lines in terms of added cost and time for deburring process. The purpose of this study is to investigate the influence of workpiece hardening on the burr formation in face milling of carbon steel AISI 1045. Before machining, laser hardening by CO2 laser is irradiated on the side face along the line where burr is expected to be formed. The laser irradiated area of carbon steel has high hardness and brittle characteristic in comparison with mother phase. In case of machining laser hardened workpiece, the burr height was smaller compared with standard steel. By controlling laser irradiation conditions, burr is not observed so that the chipping (negative burr) like chamfering is caused. From these results, it was clarified that laser hardening is effective to prevent burr formation and this technique can be applied to high efficiency processing.

Abstract: The optimization of processing parameters for laser cladding process based on Statistical Analysis System (SAS) software was investigated and the experimental investigation on Ni-based alloy components fabricated by laser cladding was carried out. The influences of the main processing parameters on the surface quality were analyzed, and the Ni-based components with superior surface quality were obtained by employing the optimum set of parameters. The surface morphology and microstructure of the components were analyzed. Results indicate that the surface of the cladding is rather smooth and the claddings have a unique microstructure consisting of primary dendrite. The laser cladding layer with integrated melt interface and without reheat cracking can be obtained by optimizing the process variables. The investigations show that the components fabricated by laser cladding process have better mechanical properties than that of the conventional manufacturing technology.

Abstract: This study discusses a method for increasing the efficiency and speed with which an improvement in surface roughness of a hole-wall surface can be achieved. The surface after traditional machining is discussed as well as a method for finishing the hole-wall surface using a design of finish-tool that includes a nonconductive knothole-form burnishing-tool and a ring electrode to execute simultaneous burnishing and electrofinishing (SBEF). By the dual and synchronous effect of the electrode and the burnishing-tool a superior hole-wall finish is achieved. In the experiment, the use of a small arc rounding radius and a thin finish-tool is advantageous to the finishing effect. A high rotational speed of the finish-tool produces a better finish. A high current and a faster finishing tool feed is also effective in gaining a rapid improvement of the roughness of the hole-wall surface and is recommended from the results of the current study.