Advanced Materials Research Vol. 500

Abstract: This paper investigates the effects of MQL system on the grinding performance of Ti-6Al-4V using SiC abrasive, the evaluation of the performance consisted of analyzing the grinding force, surface roughness and surface morphology. The experiment result indicated that the favorable lubricating effect of MQL oil makes it has the lowest value of grinding force, specific energy and force raito. MQL has better surface finish than dry grinding and fluid grinding has the lowest value of surface roughness under different grinding depth. Surface damages such as: side flow, plastic deformation, redeposition are present in dry and fluid grinding. As grinding depth increased, the damages become much more severe. But in MQL condition, it gives better surface integrity than dry and fluid grinding.

Abstract: This paper presents some research results of the application of finite element method and molecular dynamics in the simulation of grinding surface creation. The comparison of these two methods shows that both methods could illustrate the material removal phenomena and provide useful information of grinding mechanics, but they have different feasible application arranges depending on the level of size scales. The investigation demonstrated that rubbing hypothesis of grinding material removal mechanism is valid at all size level even down to nanometre level. Further investigation areas are identified in the paper.

Abstract: Particle reinforced metal matrix composites (SiCp/Al composites) have proved to be extremely difficult to machine with traditional cutting processes due to serious tool-wear and high machining cost, which lead to the low machining efficiency. This paper presents the results of an experimental research on mill-grinding of SiC particle reinforced aluminum matrix composites. Based on the Taguchi experimental design method, study on the material removal rate was carried out to gain the optimal processing parameters combination by using the analysis of S/N ratio. The detailed effect of wheel speed on material removal rate through single factor experiment was also studied. Though analysis of S/N ratio and variance, the depth of cut has greatest effect on the material removal rate, followed by feed rate. And grinding wheel speed has least effect on it. But the depth of cut and feed rate affect on the material removal rate nonlinearly. In the range of machining parameters applied, the optimal processing parameters combination gained is A2B3C3, namely, v_s=11.77m/s, v_w=100mm/min, a_p=0.8mm. Material removal rate increased at first and then there was a decreasing trend with increasing wheel speed.

Abstract: t is the goal of this paper to describe an error analysis methodology for polishing robot on a manufacturing floor. With the generalized errors considered in the model, the end-effector position and orientation errors are calculated as a function of the generalized error. The analysis is to determine which physical errors significantly influence the end-effector error. The method and computer program have been applied to the performance evaluation of a robotic manipulator to be used in a polishing robot. This methodology can be applied to estimate calibration error and give the severity value to help the designer to select the polishing robot parameters.

Abstract: Micro-structured surfaces on brittle materials, e.g. ceramic and glass, are gaining increasing application in a range of areas. In this paper, fast tool servo (FTS) diamond turning has been applied to machine micro-structured surfaces on brittle materials and the machined surfaces has been observed to study its machining mechanism. A machining model is presented to enable ductile-regime machining of the brittle material. Based on the model, machining characteristics can be predicted for given cutting conditions. Experimental investigation on machining of a micro-structured surface verified that ductile-regime machining can be ensured on the entire surface through path planning simulation based on the machining model.

Abstract: An abrasive water jet micro-turning experiment device is designed to solve the problem for micromachining the revolving parts. This device is composed of the machine body, hydraulic system, collection devices and control equipment etc. This paper emphasizes on the structure design of the moving parts of the abrasive water jet turning process, clamp, lathe bed, abrasive water jet injecting system and collection system. The turning spindle system and feed drive mechanism are designed, and the strength, stiffness and precision of the ball screw transmission mechanism are calculated and checked to meet the needs of the abrasive water jet micro-turning experiments.

Abstract: Ultrasonic-vibration-assisted micro-cutting of Ti-6Al-4V was simulated by finite element analysis software ADVANTEDGE. During the micro-cutting of Ti-6Al-4V the cutting forces were compared between conventional and ultrasonic-vibration-assisted method. In the ultrasonic-vibration-assisted micro-cutting process different frequency and amplitude were applied on the cutting tool. The influences of frequency and amplitude were analyzed. The cutting temperature increases with the increase of the amplitude, and the cutting temperature decreases with the increase of frequency. By using the simulation method the appropriate amplitude and frequency data can be obtained.

Abstract: The mechanism of ultrashort pulsed laser ablation of polycrystalline diamond (PCD) is investigated using molecular dynamics simulation. The simulation model provides a detailed atomic-level description of the laser energy deposition to PCD specimens and is verified by an experiment using 300 fs laser irradiation of a PCD sample. It is found that grain boundaries play an important role in the laser ablation. Melting starts from the grain boundaries since the atoms in these regions have higher potential energy and are melted more easily than the perfect diamond. Non-homogeneous melting then takes place at these places, and the inner crystal grains melt more easily in liquid surroundings presented by the melting grain boundaries. Moreover, the interplay of the two processes, photomechanical spallation and evaporation, are found to account for material removal in ultrashort pulsed laser ablation of PCD.

Abstract: Micro-end-milling is an efficient and economical manufacturing operation that is capable of accurately producing high aspect ratio features and parts. It is important to study the cutting forces in micro-milling for the planning and control of the process. This paper presents an experimental study of the cutting forces in micro-end-milling of a 6160 aluminum alloy. The measured cutting forces are presented and discussed for different cutting conditions, such as various feeds per tooth, cutter diameters, and cutting speeds. It is found that the peak cutting forces increase with increasing cutting speed and feed rate. The effects of tool runout on the cutting forces were also analyzed based on the experimental results, from which the influences of feed rate and cutting speed are found to be obvious.

Abstract: Magnetic sensors are widely used in areas such as high-density magnetic recording, navigation, military and security, target detection and tracking, anti-theft systems, non-destructive testing, magnetic marking and labeling, geomagnetic measurements, space research, measurements of magnetic fields onboard spacecraft and biomagnetic measurements in the body ¹. For magnetic sensors used to detect weak magnetic fields, a highly sensitive sensing element, with extremely high permeability, is needed. Permalloy is useful due to its initial high permeability and near-zero magnetostriction. Current fabrication methods used to produce these sensing elements include sputtering, electroplating, cold drawing and wet etching. Laser ablation, however, has always not been seriously considered due to domain pinning effects induced by nanosecond lasers². Femtosecond laser machining, on the other hand, has shown great potential in processing such soft magnetic materials without affecting its permeability. In fact, Jia et al. had observed that when femtosecond laser micromachining was carried out on FINEMET, the amorphous phase was observed to remain in the damaged zone and few crystallization was found in the ablation zone³.