Advanced Materials Research Vols. 314-316

Abstract: High-speed cutting technology is widely used in aviation, mold, automotive industries and other fields for its high machining efficiency, smaller cutting force, less cutting heat and high machining precision. However, the production site in China, high-speed machine tools do not really play its role in some enterprises, without real sense of the high-speed machining. Aluminum alloy 2A70 as the research object, using single-factor test, study the effect law of high-speed milling parameters on milling force here. The results show that: the cutting force is varying for high-speed milling, showing a periodic variation, with the transient characteristic, the milling force is large amplitude fluctuations in X and Y direction, the amount of change is respectively 55.544N and 56.306N. Milling force influenced by the spindle speed, with the increase of spindle speed, X contribute to the greatest change in the direction of milling, Y direction second, Z direction is almost unchanged. Under the experimental conditions, the stability high-speed cutting area of 2A70 is the spindle speed in the area of 21000rpm~27000rpm. The results of high-speed milling of aluminum alloy have certain significance.

Abstract: In this paper, a miniaturization nanoindentation and scratch device was developed. Finite element analysis was carried out to study static and modal characteristics of x/y flexure hinge and z axis driving hinge as well as effect of geometric parameters on output performances of z axis driving hinge. Results indicated that x/y flexure hinge and z axis driving hinge had enough strength and high natural frequencies. Geometric parameters of z axis driving hinge affected output performances significantly. The model of developed device was established. Indentation experiments of Si and amorphous alloy showed that the developed miniaturization nanoindentation and scratch device worked well and can carry out indentation experiments with certain accuracy.

Abstract: In this paper, we proposed a method to fabricate a D-shaped optical fiber of Bragg surface grating filter component by D-shaped fiber polishing along with photolithography、holographic interference lithography technologies and micro-molding process. The optical fiber was side-polished until it reaches the core of fiber. The master Bragg grating was first fabricated on the positive photoresister by using the holography interference lithography, then the patterned resist was used as a mother mold to transfer the pattern onto a hard polydimethylsiloxane (hPDMS)/ polydimethylsiloxane (PDMS) mold. The gratings pattern on hPDMS/PDMS was then transferred onto the UV polymer on the surface of a D-shaped fiber using a UV replication process. The transmission spectra of the resulting gratings were measured, with test results showing the transmission dip of -17dB , and 3-dB-transmission bandwidth of 9nm.

Abstract: This paper presents mechanisms studies of micro scale milling operation focusing on micro cutter edge radius. To address this issue, the tool wear model is developed in the present work. Starting with an analysis of the milling edge radius of the tool, the influence of the downscaling on the edge radius is determined by analyzing the milling force. This simulation is used to predict the extent of tool wear in the same milling operation condition by increasing of the tool edge radius. This model accurately predicted the increasing of force with tool wear progress and provides the means for further study of the micro milling tool wear.

Abstract: The development of new, advanced engineering materials and the need for precise flexible prototypes and low volume production have made Micro-EDM and important manufacturing process to meet such demands. The most important parameters in Micro-EDM are the material removal rate (MRR), the tool wear rate (TWR), accuracy and surface texture. The influence of peak current, gap voltage, pulse duration and process parameters plays important role in determining the material removal rate and tool wear rate on Micro EDM. Thus, this paper describes the development of the Micro-EDM based on the tool wear rate and material removal rate of the system using directly mounted APA 400MML actuator as the tool feed control system.

Abstract: To address the mainstream technology of UV-LIGA combined with micro-electroforming which could only fabricate micro-moulds cavity with vertical wall structure and low depth-to-width ratio, a new forming process based on femtosecond laser combined with laminated slip-welding was proposed in the paper. The forming process was achieved through experiment and it proved that the forming process could be a useful method for the process of micro-moulds with high depth-to-width ratio and complex structures. Work-pieces which were 0Cr18Ni9 stainless steel foils whose thickness was 20μm were welded by resistance welding machine and the microstructure of welding-zone was observed in detail. It was found that the welding-zone was composed of nugget zone, fusion zone and heat affected zone. Through the study of welding mechanism, the cooling rate of nugget zone was 3.99×104K/s and there was dynamic recrystallization in nugget zone. For further study, through the X-ray diffraction (XRD) test, it was found there were no chromium carbide and iron-copper eutectic alloy in nugget zone.

Abstract: In this paper, use the basic principles of near infrared to detect the spectral characteristics of apple, as the research object of Fuji apple, and then establish the model of near infrared technology forecasting apple sugar content, to discover the sugar content in apple. The results show that near infrared transmission spectroscopy can be used as an accurate, reliable, nondestructive testing method, the test has obvious advantages for detecting indicators of Fuji apple sugar.

Abstract: In order to precisely get the assembly statement when two micro-mechanical parts are touching, assembly methods mapping the nonlinear relationship between micro-force/torque and assembling pose are studied. The research platform is 12 degree-of-freedom (DOF) microassembly system with large-motion-range and precise-motion-accuracy. After assembly mechanism of micro- mechanical system is introduced, assembly methods utilizing both three-dimensional (3D) search algorithm and Back Propagation (BP) neural network are brought forward on the basis of micro-force/torque information feedback. In addition, two different neural network algorithms -- gradient descent and Levenberg-Marquardt (L-M) -- are further applied in the assembly process. Comparison among above algorithms was carried out in experiments, and the results indicated that BP neural networks were more reliable than 3D search algorithm in the relationship mapping process while the convergence rate of L-M algorithm was much faster than that of the gradient descent.

Abstract: A new planar micro-transformer having sandwich spiral coil structure is fabricated using MEMS micro-fabrication technique. Stack interwinding coil is designed to achieve high coupling and higher winding number at relatively small coil area. In this work, stack sandwich interwinding coil structure is fabricated by bonding the substrates of the coil at connection pads using conductive epoxy material. This method replaces the use of conventional via connections that cause the most problem of current conductance in planar structures. The inductance of fabricated coil are measured at wide range of operating frequency using cascade GSG probe. The results show that the proposed technique is an alternative way in fabricating a simple and cost effective 3-dimensional structure of stack micro-transformer.

Abstract: A Micro Wire Electrical Discharge Machining (MWEDM) prototype is developed for fabricating micro complex parts. It mainly includes granite basement, micro energy pulse generator, precise servo mechanics, detection and servo control system, constant tension winding systems. Experiments are done on the prototype. Experimental results show that: the peak current and pulse duration have obvious influence on surface roughness and machining time, and they also have an optimum value for the highest cutting speed. The servo reference voltage also influences the surface roughness and machining time. Utilizing micro wire electrode with diameter in 30m, the MWEDM can machine micro slot with minimum size of 38m, which proves that the discharge gap width can be controlled not more than 4um, and so small discharge gap is beneficial for part’s machining accuracy. All kinds of complex micro part (such as micro gear, micro bearing bracket, micro shaped holes, etc.) can also be machined by this prototype.