The ageing of aluminium alloy that is bringing specimens to be baked at a specify temperature . When it reaches temperature we want , we will remove specimens from the oven and then quench it into the water. After the belt sander to smooth shift. Then left at room temperature for various times and then were measured hardness. Why leave it at room temperature at the time in order to compare the strengths of each of the left. After the specimen was left at room temperature for a period equal to the heat for 1 minute, 1 hour, 2 hours and 4 hours to evaluate the hardness is the time it takes to bake. The benefits derived from precipitation ageing is that the part will be strong increase after left at room temperature, the hardness is increased slowly by the time that was left. And when it is baked on hardness will increase dramatically. The hardness is increased By the time it takes to bake.