Development of measurement system for powder flowability based on vibrating capillary method

An automatic measurement system for evaluating powder flowability based on the vibrating capillary method has been studied experimentally. The vibration amplitude was controlled by a computer, and the vibration acceleration and the mass of particles discharged from the capillary were obtained by digital processing. The measurement time was 2 min and the amount of the powder required for each measurement was less than a few grams. To characterize the dynamic powder flowability, evaluation factors were developed. A series of experiments was conducted using powders with mass median diameters from 5.2 to 58.2 μm, showing that this measurement system can fully evaluate the powder flowability.     

Effect of grain refiner and grain size on the susceptibility of Al–Mg die casting alloy to cracking during solidification

The die casting process and its alloys have been developed in recent years for automobile body parts such as B-pillars. However, it is known that die casting alloys with high ductility and fracture elongation often show a higher susceptibility to cracking during solidification than conventional Al–Si alloys. Thus, it is important to estimate and control the susceptibility to cracking during solidification before trial casting or mass-production. In this study, as a representative non-heat treatment type alloy, Al–4.5wt%Mg (JIS AC7A, AA 514) aluminum alloy was used. The effect of the addition of silicon and grain refiner on the reduction of the susceptibility to cracking was examined. In order to evaluate the susceptibility to cracking, both the “I-beam casting cracking test” and the “TIG spot welding cracking test” were carried out. As a result, the addition of Ti + B worked as a grain refiner on both testing methods. The susceptibility to cracking was significantly reduced by the addition of Ti + B in both the I-beam casting and the weld crater. It was found that the finer grain size led to lower susceptibility to cracking. Furthermore, the susceptibility to cracking of the die casting product decreased with the addition of Ti + B.     

A study on the prediction of machining accuracy

The machining accuracy prediction has been widely studied in many manufacturing processes to achieve efficient control for production process. In this paper, a dynamic analysis model is proposed to develop the prediction model of machining accuracy. The dynamic analysis model has the advantage of high predictable power of the GM(1,1) model while at the same time utilizing the prediction power of the Markov chain model from stochastic process theory. Furthermore, Taylor approximation method is employed to enhance the prediction accuracy. The effectiveness of the proposed model is validated with a real case.