CUTTING REGULARITY AND DISCHARGE CHARACTERISTICS BY USING COMPOSITE COOLING LIQUID IN WIRE CUT ELECTRICAL DISCHARGE MACHINE WITH HIGH WIRE TRAVELING SPEED

The analysis of cutting regularity is provided through using and comparing two typical cooling liquids. It is proved that cutting regularity is greatly affected by cooling liquid＇s washing ability. Discharge characteristics and theoretic analysis between two electrodes are also discussed based on discharge waveform. By using composite cooling liquid which has strong washing ability, the efficiency in the first stable cutting phase has reached more than 200 mm^2/min, and the roughness of the surface has reached Ra〈0.8 μm after the fourth cutting with more than 50 mm^2/min average cutting efficiency. It is pointed out that cutting situation of the wire cut electrical discharge machine with high wire traveling speed （HSWEDM） is better than the wire cut electrical discharge machine with low wire traveling speed （LSWEDM） in the condition of improving the cooling liquid washing ability. The machining indices of HSWEDM will be increased remarkably by using the composite cooling liquid.

Experimental investigation of tool wear and chip formation in cryogenic machining of titanium alloys

Titanium alloys are one of the most important design materials for the aircraft industry. The high strength-to-density-ratio and the compatibility with carbon fibre reinforced plastic are the reasons for a raising application in this field. The outstanding properties lead to challenging machining processes. High strength and low heat conductivity affect high mechanical and thermal loads for the cutting edge. Thus, the machining process is characterized by a rapid development of tool wear even at low cutting parameter. To reach a sufficient productivity it is necessary to dissipate the resulting heat from the cutting edge by a coolant. Therefore the cryogenic machining of two different titanium alloys is investigated in this work. The results point out the different behavior of the machining processes under cryogenic conditions because of the reduced thermal load for the cutting tool. According to this investigation, the cryogenic cooling with COa enables an increase of the tool life in comparison to emulsion based cooling principles when machining the α＋β-titanium alloy Ti-6Al-4V. The machining process of the high strength titanium alloy Ti-6Al-2Sn-4Zr-6Mo requires an additional lubrication realized by a minimum quantity lubrication （MQL） with oil. This combined cool- ing leads to a smoother chip underside and to slender shear bands between the different chip segments.

Simultaneous characterization of multiple properties of solid and liquid phases in crystallization processes using NIR

Near infrared spectroscopy （NIR） is now probably the most popular process analytical technology （PAT） for pharmaceutical and some other industries. However, unlike mid-IR, NIR is known to have difficulties in monitoring crystallization or precipitation processes because the existence of solids could cause distortion of the spectra. This phenomenon, seen as unfavorable previously, is however an indication that NIR spectra contain rich information about both solids and liquids, giving the possibility of using the same instrument for multiple property characterization. In this study, transflectance NIR calibration data was obtained using solutions and slurries of varied solution concentration, particle size, solid concentration and temperature. The data was used to build calibration models for prediction of the multiple properties of both phases. Predictive models were developed for this challenging application using an approach that combines genetic algorithm （GA） and support vector machine （SVM）. GA is used for wavelength selection and SVM for mode building. The new GA-SVM approach is shown to outperform other methods including GA-PLS （partial least squares） and traditional SVM. NIR is thus successfully applied to monitoring seeded and unseeded cooling crystallization processes of L-glutamic acid.