Effects of various process variables on average flow velocity of LFC liquid aluminum in the mold have been studied. The results show that thermal insulation coating and suitable coating thickness are helpful to improving the filling velocity of liquid aluminum. The higher the pouring temperature or the larger the sprue hollow area rate is
the faster the filling velocity of molten aluminum is. The larger the thickness of pattern is
the slower the filling velocity is. It will be helpful to improving the filling velocity when the sprue length and sprue areas are controlled to some extent. Vacuum pressure will improve the filling velocity greatly.