To monitor the stirring state by on-line estimation of liquid viscosity instead of stopping the stirring process and measuring the viscosity using viscometer, a basic study clarifying the effect of stirring conditions was carried out. For this purpose, the relationship between liquid viscosity and the stirring conditions, such as stirring torque, stirring speed, the duty ratio of PWM, impeller and beaker type, and the blade position in the beaker was analyzed. The second-order relationship between the stirring speed and torque, the linear relationship between viscosity and torque, and the linear relationship between duty ratio of PWM and stirring speed were observed, thereby indicating that the liquid viscosity could be estimated by an experimental formula based on the duty ratio and the stirring speed. In addition, the type of impeller and beaker was identified using the magnetic field inside impeller and RFID technology. For reducing the error in calculating the liquid viscosity, the employment of an impeller blade with a large rotational resistance and stirring with the blade at the center zone of the beaker were found to be necessary.

In the chemical plating of the randomly loaded workpiece, it is very important to promote the agitation of plating solution and secure the space for the chemical reaction. This study investigated the possibility of chemical plating using only vibration, as well as the plating characteristics for a combination of vibration and pressurized floating. The results of the study indicate that it is possible to perform chemical plating with only vibration, and the amount of plating increases as the vibrating frequency increases. Additionally, when combined with the vibration and pressurized floating, the probability of securing a chemical reaction space and the probability of stirring become high, resulting in highly effective plating.

To identify the impeller types automatically for an overhead stirrer operation, a digitalization of the analog magnetic signal of the permanent magnet arrays was performed. The permanent magnets were installed into the impeller shaft in NS-SN array, and their magnetic fields were measured by a hall sensor while the impeller was mounted on the stirrer. Results of the experiments and finite element analysis showed that the number of peaks of magnetic field signal was observed corresponding to the number of magnets. Considering the consistency of the number and the magnitude of magnetic field peaks, it was found to be more advantageous to measure the magnetic field in the axial than in the radial direction of the impeller. For eliminating the influence of the noise included in the analog signal and connecting it with the micro-controller of the stirrer, the analog magnetic field signal was transformed to the digital-pulse-patterned signal through DC offset, amplification, absolute value, and the comparator circuit. Through these processes, the error in identifying the impeller type could be significantly reduced compared with directly using the magnitude of the analog magnetic signal.

The solid state dissimilar joining of mild steel and aluminum 5052-O alloy is successfully achieved by friction stir welding (FSW). The 2 mm thick sheets are butt welded using a convex scrolled tool made of tungsten carbide. With a constant weld speed of 75 mm/min, two different tool at rotation speeds of, 800 and 1000 rpm, were employed to determine the feasibility of the joint formation. Macroscopic observation of the cross section confirmed the formation of a sound FSW joint. However, the formation of an intermetallic in the Stir Zone (SZ) is also observed for the both sets of process parameters. Comparatively, better material mixing is observed when the parameters are set at, 1000 rpm and 75 mm/min respectively. The hardness test revealed the presence of three distinct hardness zones in the SZ for the two parameter sets.