Zinc-aluminum alloy gear box cover and preparation process thereof

The invention relates to the technical field of a gear box cover, and in particular relates to a zinc-aluminum alloy gear box cover and a preparation process thereof. The gear box cover is made of a zinc-aluminum alloy material, wherein the zinc-aluminum alloy material consists of the following chemical components by mass percent: 94.5 to 96.5 percent of zinc, 3 to 5 percent of aluminum, 0.02 to 0.04 percent of magnesium, 0.4 to 0.6 percent of copper, 0.006 to 0.009 percent of iron, 0.002 to 0.004 percent of impurity lead, 0.0005 to 0.0015 percent of cadmium and 0.0001 to 0.0008 percent of tin. The preparation process comprises the steps such as smelting, die-casting forming, polishing, flash removing, grinding and CNC machining. The gear box cover is easier to assemble, high in wear resistance, excellent in mechanical property and long in service life; the process is simple, the quality is stable, the production efficiency is high, the overall cost can be reduced by more than 50 percent, and the industrialized mass production can be realized.