Such a large sheet metal part will inevitably warp by conventional methods, and the so-called flatness is difficult to guarantee. Let's see if we can look at it from two aspects: material and technology: Has the 1 aluminum plate been thermally flattened? Some domestic factories provide this kind of plate; 2) Adjust the tool path to make it stress evenly; 3) If the quantity is large and the pressure of the CNC punch is large enough, we can consider making a special punching knife, such as punching all square holes in the direction of radian at the same time, or punching in two steps; That's what we did then. It doesn't matter if the quantity is small. We have a part with only 20 pieces per month, which requires extremely high flatness. Even if the stamping die is opened, it can only be cut by laser. I hope it helps.