THE EFFECT OF RISER USE IN THE QUALITY OF CASTING AL 7075 FOR SHIP PROPELLER

Casting with Al 7075 alloys is considered to have good mechanical properties. The quality of casting products is also influenced by gating systems, riser use and mechanical properties. The purpose of this study was to determine the mechanical properties of propeller cast products using a riser, applying the use of risers to produce flawless products. The research method is propeller casting using two gating systems and using a riser. The results of this study indicate that from the two propeller casting using a riser in the TIP section but the hardness value is different, namely directly gated with the riser in the TIP section 73.24 HB, section HUB 72.24 HB. While on the upper channel with risers at TIP 67.5 HB, HUB 75.44 HB. For the micro structure there is a porosity defect on the channel directly with the riser caused by the freezing process during the pouring process of metal liquid in the mold, the direct channel with the riser is defect that occurs on the propeller leaves, while the upper duct with the riser is not defective and the results are perfect.