No abstract

No abstract

In the present study, the effects of operating parameters, namely, rotor speed, feed rate, and inlet air velocity, on the cut diameter of a cage-type separator were studied. The design of experiments (DOE) method was used to investigate the relationship between the operating parameters and the cut size. The experimental results were statistically analyzed using MINITAB 16 software. Both the rotor speed and air inlet velocity had significant main effects on the cut size. The feed rate was also significant but had a weak effect with respect to the rotor speed and inlet air velocity effects. The cut size decreased with an increase in rotor speed and increased with an increase in air inlet velocity. However, the cut size slightly decreased with an increase in feed rate. An empirical multiple-variable linear model for predicting the cut size of the classification was created and presented. The results derived from the statistical analysis were in good agreement with those from the experiments, additionally extended from the DOE. The optimal conditions for classification of SAC305 powder with size range 25–40 μm were obtained when the turbo air classifier was operated at rotor speed 406 RPM, the feed rate 4 kg/h, and the air velocity 5 m/s. The smallest cut size of the classifier was about 27.8 μm.

Centrifugal atomization apparatus was constructed to produce solder alloy powder with high quality. In this work, SAC305 alloy was atomized to study the effects of processing parameters, including atomizer disk surface condition and oxygen content in the atomizer chamber on the mean particle size, size distribution, production yield, and morphology of the produced SAC305 powder. The results showed that the atomizer disk surface coated with tin alloy gave the produced powder with smaller mean size, narrower size distribution and higher production yield, in comparison with the uncoated disk. This is due to a good wettability between the molten SAC305 and atomizer disk surface and the sufficient time for alloy droplets to be solidified. The shapes of SAC305 powder were sphere, teardrop, oval, and ligament, depending on the oxygen content in the atomizer chamber during atomization. The shape of produced powder was almost perfectly spherical when the oxygen content was decreased down to 0.5 vol.%. Moreover, with decreasing the oxygen content in the atomizer chamber, the produced SAC305 powder would contain oxygen content on its surface lower than 100 ppm.

With an increasing pressure on automotive weight reduction, the demand on the lighter weight automotive components continues to increase. In recent years, squeeze casting processes have been used with different aluminium alloys to produce high integrity automotive parts. In this study, the indirect squeeze casting processes is adopted to cast a motorcycles component originally produced by a high pressure die casting process using aluminium alloy ADC12. To minimize amount of gas porosity inside squeeze casts, concepts of (1) minimization of ingate velocity along with (2) bottom filling pattern during the die filling, and (3) maximization of intensifications casting pressure are applied. Then parts are casted with both conventional high pressure die casting and indirect squeeze casting processes. Comparative evaluation of mechanical properties was made between HPDC casts and squeeze casts both in as-cast and heat treated conditions. Results from the experiment have shown that squeeze casts can pass the blister test at 490 °C for 2.5 hours. Then, squeeze casts are heat treated by solution treatment at 484 °C for 20 minutes and artificial age at 190 °C for 2.5 hours, respectively. This improves UTS of the heat treated squeeze cast to 254.14 MPa with 1.84% of elongation, while the UTS of as cast condition from both processes is not significantly different.