Ha ha! This is called insert molding! In fact, before designing this workpiece, we should not only consider the shrinkage deformation of the material, but also find a good mold factory to design the mold, such as shrinkage rate. In addition, we should also consider the choice of mobile phone material. Generally, the plastic that will deform is mostly PC or PC+ABS, because this material will shrink after cooling, resulting in uneven stress and deformation. This kind of deformation can't be corrected after forming, because magnesium alloy can't be corrected simply by correcting plastic material, and plastic material will be damaged simply by correcting plastic material, so it must be considered comprehensively before design. In terms of length and width of mobile phone design, considering various designs and production, the flatness of 0.2mm can be achieved.