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Hot cracking is an important defect that occurs during solidification of aluminum-copper alloys. In this present work, the effects of mold temperature and casting temperature on hot cracking in the Al-4.5 wt.% Cu alloy has been studied using a ring mold for hot cracking assessment. For the experimental conditions, three mold temperatures between 150 and 350°C and three casting temperatures between 670 and 770°C were studied and Al-7 wt.% Si alloy was used as reference for comparison. The results showed Al-7 wt.% Si alloy has high resistance to hot cracking and no hot cracking forms under three different mold temperatures, while Al-4.5 wt.% Cu alloy shows significant hot cracking tendency under the same casting conditions. The severity of hot cracking in Al-4.5 wt.% Cu alloy decreased significantly with increasing the mold temperature and decreasing the casting temperature. On the other hand, an increasing casting temperature resulted in severer hot cracking in Al-4.5 wt.% Cu alloy.

The purpose of this research was to investigate the effects of main factors on the surface roughness in face milling process palmyra palm wood and coconut wood by computer numerical controlled milling machine and using shell end mill cutting tools 6 edges. The main factors including speed, feed rate, depth of cut and angle of cut were investigated for the optimum surface roughness. The result of preliminary trial showed that the depth of cut and the angle of the cut had no effect on surface roughness. It was found from the experiment that the factors affecting surface roughness were feed and speed, with tendency for reduction of roughness value at a lower feed rate and greater cutting speed. Therefore, in the facing process for palmyra palm wood it was possible to determine a face milling condition by means of the equation Ra = 0.954 + 20.4 Feed + 0.00126 Speed. This equation was employed at a limited speed of 800-1200 rpm, and the feed rate of 0.03-0.05 mm/tooth. The result from the experiment of the mean absolute percentage error of the equation of surface roughness is 6.10% which is less than the margin of error, and is acceptable. For coconut wood it was found from the experiment that the factor affecting surface roughness was feed rate and cutting speed, with tendency for reduction of roughness value at lower feed rate and greater cutting speed. Therefore, in the face milling coconut wood it was possible determine a facing condition by means of the equation Ra = 4.72 - 0.000864 Speed + 0.00443 Feed. Leading this equation goes to use is in limitation cutting speed 1000-2000 rpm at feed rate 100-300 mm/min. The result from the experiment of mean absolute percentage error of the equation of surface roughness is 4.64% which is less than the margin of error, and is acceptable. As a result, the selection of optimal machining parameters can be greatly benefited to the Coconut wood furniture manufacturing industry in terms of productivity improvement.