模具具有特定的轮廓或内腔形状，具有刃口的轮廓形状可以使坯料按轮廓线形状发生分离，即进行冲裁；内腔形状可以使坯料获得相应的立体形状。
The die has a specific contour or cavity shape, the contour shape with edge can separate the blank according to the contour shape, that is to say, blanking; the cavity shape can make the blank obtain the corresponding three-dimensional shape.
模具一般分为两个部分：动模和定模，或凸模和凹模，它们可分可合。分开时装入坯料或取出制件，合拢时使制件与坯料分离或成形。在冲裁、成形冲压、模锻、冷镦、压制和压塑过程中，分离或成形所需的外力通过模具施加在坯料上；在挤压、压铸和注塑过程中，外力则由气压、柱塞、冲头等施加在坯料上，模具承受的是坯料的胀力。
The die is generally divided into two parts: moving die and fixed die, or punch and die, which can be separated and closed. When separated, the blank is put in or the workpiece is taken out, and when closed, the workpiece is separated from the blank or shaped. In the process of blanking, forming and stamping, die forging, cold heading, pressing and pressing, the external force required for separation or forming is exerted on the blank through the die; in the process of extrusion, die casting and injection molding, the external force is exerted on the blank by air pressure, plunger, punch, etc., and the die bears the expansion force of the blank.