Papers by Keyword: Grinding Fluid

Abstract: In the hole drilling process, produced chip cannot be released from the inside hole which leads to broken glass plate due to the adhered chip on tool. Chip discharge method was announced by many researchers. However, the method using the tool-only with drilling command is rarely seen. In this laboratory, we have developed a tool in order to discharge chip. The developed tool is capable in preventing chip adhesion and producing high quality and efficient hole drilling process. The developed tool has several hundred times longer tool life than a conventional tool. However, the amount of adhered chips on cutting tool increase as the number of hole drilling process increases. The chip adhesion condition is different according to the kind of grinding fluid. Adhesion of chips on tool can be related to the properties of grinding fluid. Thus, in this study, the types of grinding fluid used during the hole drilling process were investigated to determine the state of chip adhesion. Three types of grinding fluid used are Emulsion, Soluble and Solution and all of them include surfactant which is considered to have an effect on prevention of chip adhesion. The main conclusions obtained in this study are as follows. Chip adhesion state was investigated after drilling process and it was found that instead of grinding fluid properties, surfactant also has significant effect on chip adhesion on tool by absorbing the adhered chip from the tool. The results showed that grinding fluid with long-chain surfactant has small amount of chip adhesion whereas grinding fluid with short-chain surfactant has large amount of chip adhesion. Therefore, it can be concluded that grinding fluid with long-chain surfactant is capable in preventing chip adhesion during hole drilling process.

Abstract: Ultrasonic excited fluid has been researched for machining of hard-to-grind materials. Ultrasonic vibration is applied to grinding fluid by an ultrasonic oscillating comb-shape effecter with integrated nozzle. Grinding fluid discharges from a nozzle placed between the comb’s feet and passes through the vacant space between comb teeth. By this setup, flowing grinding fluid can be continuously excited by ultrasonic vibration. Based on the principle of an ultrasonic washing machine, impulsive force caused by cavitation bubble will reduce the adhesion of chips on the cutting face of grain and chip pockets. Some effects of ultrasonic excited grinding fluid have been recorded such as reducing grinding heat in the case of grinding for Titanium alloy and decreasing in grinding force, improving surface roughness in the case of grinding for Aluminum and stainless alloy. However, the reason of better grinding performance is still unknown. Therefore, experiments conducted with different type of grinding fluids with and without ultrasonic vibration are needed. Pure Titanium, which considered a hard-to-cut material, is chosen as work material. Grinding forces and grinding heat during grinding will be measured and evaluated to clarify the mechanism of ultrasonic excited grinding fluid.

Abstract: For optimization and control of the grinding process, it is necessary to monitor the process state. Fluid selection for grinding process is also considered as key factor for surface quality. This study focuses on the effects of different fluids in grinding process using Acoustic Emission technology. The analysis is carried out grouping the tests according to the main measured: Acoustic Emission (AE) signals, Normal and Tangential Forces on the workpiece surface, Grinding Temperature and Surface Roughness. The potential of real-time monitoring grinding process using Acoustic Emission technology is also tested. The results of this research show that selections of grinding fluids do have a significant influence on response factors such as surface roughness and AE signals. Further, prediction of surface roughness during the grinding process using AE signal monitoring is demonstrated in this work.

Abstract: A doubled-sided lapping machine of grinding stone manufactured of a SiC as an abrasive, specific resin and other thermosetting resin were developed for grinding process of the substrate of hard disk drive (HDD) made up of aluminum since the conventional lapping machine cause the serious quality problem of the magnetic substrate. However, at certain parameter during the grinding process, the abrasive stone was clogging due to the agglomeration of debris from the substrate which cause scratches on the magnetic substrates and affect its performance. The samples were classified into four parts (soft spot, border spot, hard spot, and unused spot). Characterizations of the samples were done using XRF, SEM and FTIR analysis. Based on all the above analysis, it can conclude that the porosity of the stone were not homogeneous and the percentage of Al was highest at the border spot which shows that, the area at the border spot cause the clogging to occur thus produces the hard spot that will damage the magnetic substrate during grinding process.

Abstract: The grinding heat directly affected workpiece surface in the grinding process and it might produce some defects such as crack and burn. Meanwhile wear debris generated in the grinding process could easily embed grinding wheel blowhole and caused clogging and passivation. So it was particular important to avoid defects and improve the grinding workpiece surface integrity effectively. This paper established an incompressible turbulent fluid spray model based on the study of the existing airflow and the grinding fluid distribution in the grinding zone. Then according to different grinding fluid supply parameters established the two-phase gas liquid spray flow model by using CFD(computational fluid dynamics), simulated and calculated the model, compared the mass flow rate of the grinding fluid flow field with different spray distances, heights, speeds and spray angles in the grinding zone and determined the most reasonable spraying jet position. At the last, through researching on the workpiece surface integrity experiment, it provided an experimental basis to determine the most suitable spray jet position and verify the rationality of supply parameters selection.

Abstract: We explored the effect of supplying coolant from the inner side of a grinding wheel on the residual stress caused by grinding. Effect of depth of cut on grinding temperature and residual stress was also studied. Results clarified that grinding with an internal coolant supply induced a larger compressive residual stress compared to a conventional external grinding fluid supply when depth of cut was large. In addition, grinding temperature in the internal grinding fluid supply was lower than in the external grinding fluid supply, as measured by infrared thermograph camera. Findings suggested that large compressive residual stress was obtained in the case of the coolant supplied from the inner side of the grinding wheel because temperature was lower than external coolant supply.

Abstract: The grinding liquid concentration has a great influence to its application and cost. Based on the tribological properties, viscosity, heat capacity, the research was conducted to find the performance of grinding fluid with difference concentration. Experimental results show that the grinding fluid can be chosen with low concentration in the process of cutting grinding. For the flat surface grinding and the cylindrical grinding, appropriate method is to give high grinding liquid concentration.

Abstract: The grinding performance is strongly affected by grain condition. Especially loading directly raises the grinding force, reduces tool life and deteriorates accuracy of machining. In this study, ultrasonic exciter which applies vibration energy on grinding fluid was developed. The resonant frequency of 28kHz. The exciter is set between the fluid supplying nozzle and grinding wheel. The discharging grinding fluid from the nozzle is supplied to grinding wheel between the teeth of comb-shape horn. The performance is verified on surface grinding machine with vitrified WA grinding wheel. It was experimentally demonstrated that the excited grinding fluid prevented the loading and improved the surface roughness even for grinding of aluminum. And also improvement of surface roughness was recognized on alloy tool steel.

Abstract: The grinding fluid has the function of cooling and lubricating only when it breaks through the airflow barrier near the grinding wheel and enters into the contact area between the grinding wheel and the workpiece. The air-fluid two-phase flow software is used to simulate the characteristics of the grinding fluid field based on VOF, and the special constraint conditions of the outlet pressure are not applied in simulation. The characteristics of the grinding fluid jet and the real moving characteristics of the grinding fluid between the jet flow area and the grinding area are analyzed. It provides the research foundation for the parameters of the grinding fluid supplying.

Abstract: This paper proposes a new grinding-fluid-supply system for improving the grinding performance of a CBN wheel. The system generates cavitations in the fluid flow, which is expected to provide higher cooling and superior grinding-chip removal capability. The system is applied to one-pass surface grinding of steel plates, and residual stress and surface roughness are evaluated. The system has a major effect on improving surface roughness, but has a minor effect on reducing the residual stress under shallow-cut grinding conditions. The effects appear greater under the heavier grinding conditions.