Advanced Materials Research Vols. 652-654

Abstract: The two hybrid algorithms of back propagation neural network and immune genetic algorithm were used in the optimum design of the hot pressing parameters of Ti(C, N) matrix nano-composite ceramic die material. The BP algorithm could set up the relationship well between the hot pressing parameters and single mechanical property. Compared with the experimental value, the relative error of fracture toughness, hardness and flexural strength is only 4.65%, 0.23% and 4.05%, respectively. After analyzed the predicted results, the best predicted results were the sintering temperature was about 1455°C and the holding time was 11 min. Under these hot pressing parameters, the best flexural strength and the best fracture toughness of the material could be obtained.

Abstract: Attempts have been made to develop a gray value-matching detection method for quantitative evaluation of defects and density of green parts in metal injection moulding, based on the analysis of X-ray digital radiography images. The results show that the range of gray values should be in about 1.4% when the dimensional accuracy is required within 0.3%, and voids are present where fluctuation of the gray value is larger than 10%. The quantitative evaluation of voids, powder content and density distribution through the gray value-matching can respectively predict severity of voids, shrinkage, and deformation in the sintering stage. Furthermore, the ability to detect defects and particle density distribution of this method allows for the development of an inference system to predict the optimal parameters.

Abstract: A thin-wall 410L Stainless metallic honeycomb has been fabricated successfully by extruding and sintering processing. The extruded pastes are a combination of two phases: a solid phase composed of metallic powder carried by a fluid solution of water, binder and additives. The key to forming high quality, defect free honeycombs lies in the optimization of paste properties and is contingent on solids loading and fluid-phase rheology. To develop a model that predicts paste rheology, capillary rheometry was used to characterize powder pastes and binder gels used as the fluid phase. Suspension viscosity models were successfully applied to permit rapid optimization of solids content and binder gel solution for extrusion of honeycombs.

Abstract: Mar-M247 is widely used in industry for its excellent mechanical properties at high temperatures, but it has the shortcoming of difficulty manufactured. In order to obtain the cutting characteristics of Mar-M247, firstly, an end milling experiment was set up accordingly, where three types of cutting tools coated respectively by TiN, TiCN and TiAlN were employed. Then the parameters of cutting speed and feed rate were defined as the tool cutting variables. Finally, based on different cutting variables, the performance of tool wear, tool life, and workpiece surface roughness were analyzed and discussed. The results indicate when the tool coated by TiAlN, cutting speed of range 1600 ~ 3200 rpm and feed rate of range 0.06 ~ 0.08 mm / tooth are chosen together, the integrated states manufactured of the tool and the workpiece would be best, the method of this research can provide some references for studying others Nickel-based superalloys.

Abstract: Based on the analysis of NC machining precision, aiming at the influence of dynamic factors in NC machining system, the identified principle of machining conditions is proposed, also, approach of identified machining conditions in errors compensation to control increment of dynamic dimensions is put forward. The practical machining result shows that the original precision of machine and the machining precision of parts are improved.

Abstract: A new process was proposed. The disadvantage of of using brown alumina grinding wheel to grinding and lapping surface was studied in the analysis. The diamond facing tool was designed and manufactured with the solution of the key technique of the critical technical of single crystal diamond’s material selecting, grinding, welding. The face cutting parameters: “V”, “f” and “ap” were measured by experiment and academic analysis. Tt can fully meet the quality requirements of stainless steel valve flap’s surface used by one valve machinery factory; meanwhile the productivity was increased by a factor of 15, with overcoming the disadvatange of grinding and lapping valve flap’s surface.

Abstract: We propose a dynamic observation concept to pretend aged degradation of water-soluble coolant. The first-hand observation of coolants by a CCD microscope is extremely useful for monitoring the drastic appearance change. The appearance changes of coolant also could be monitored by combining the reflectance changes from the Red, Green and Blue LED lights. The physical process of absorbing light is occurred only at the specific wavelength in the water-soluble coolants. The absorbance at the specific wavelength would become a reliable indicator to predict the controlled condition of water-soluble coolant. Setting up these sensing systems to the machine tools make it possible to observe the coolant dynamically and on real time.

Abstract: Abrasive jet machining is an efficient technology for the fabrication of three dimensional micro structures on brittle materials. In abrasive jet machining, the variation or fluctuation in the amount of abrasive supply has a significant effect on the quality of the machined structures. An image processing technique is employed in this study to study the abrasive flow rate variation, in which abrasive jet pictures are captured at different moments by a Particle Image Velocimetry technology and then processed using Labview Vision Assistant and MATLAB. It shows that the abrasive flow rate fluctuates with time under the jetting conditions considered. The abrasive flow from larger nozzles or at smaller air pressures shows more profound fluctuation. Although the abrasive flow fluctuation from smaller nozzles remains almost constant when the air pressure is changed, for larger nozzles, the magnitude of the fluctuation gradually decreases as the air pressure is increased.

Abstract: In metal cutting process, the use of cutting fluids, cooling and easy chip removal causes long-term effects of cutting fluids disposal into environment. Research has also proven the health hazards on manufacturing workers who coming in direct contact with cutting fluids. Currently it is highly competitive or end-user of metal workings fluid to reduce cost and improve productivity. Considering the high cost and problems associated with health and safety, it would be desirable if the use of cutting fluids be omitted. This study investigates the flank wear behavior of coated Titanium Carbonitride (TiCN) coated tools in dry and wet machining of T6061 Aluminum alloy with the aim of obtaining the optimum cutting speed for dry and wet machining respectively. By using specific depths of cut 0.2 and 0.6 mm with feed rates of 0.4 and 0.8 mm/rev respectively, the wear was investigated for 3 different high cutting speeds; 290, 360 and 446 mm/min. Results of dry machining was compared with traditional wet machining process. The temperature of tool tip, machining time and tool wear were recorded. Wear rate of the tool increases with the increasing cutting speed and parameters for both dry and wet machining. Wear percentage difference for dry machining was found to be 21-37 % (d = 0.2 mm and f = 0.4 mm/rev) and 41 - 58% (d = 0.6 mm and f = 0.8 mm/rev) higher than wet machining. The optimum cutting speed for both cutting parameters is 446 m/min for dry and wet machining. Tool tip temperature for dry machining is found to be 14 - 16 % higher than wet machining for both cutting parameters. It is observed that dry machining is suitable for high speed intermittent cutting operations.

Abstract: It is well known that abrasive water jet(AWJ) was developed as a kind of high-density energy processing technologies. AWJ is used to obtain cutting quality of various materials such as metal, ceramics, glass and composite materials within a short manufacturing time because of the characteristics of heatless and noncontact processing. However, surface roughness and dimension error like round, burr, taper depend on the cutting conditions such as pump pressure, cutting speed, orifice diameter, stand off distance, abrasive flow rate and workpiece. In this paper, the effect of the shape of mixing chamber on surface quality is studied. Parabolic mixing chamber is proposed and performance is compared to that of cylindrical mixing chamber by experiment. The surface roughness was improve 0.15㎛ to 2.29㎛ and the taper angle was improve 0.0716° to 0.143° by parabolic mixing chamber.