<p>Since mold is closed in deep drawing, monitoring part quality variation to avoid defects is difficult. Existing efforts indicated that process energy, which is the accumulation of punch force over the drawing depth, has a strong correlation with part thickness variation. Thus, a process energy map is proposed to characterize the thickness variation by color and its intensity. The monitoring principle of the map, i.e., process energy varies quantitatively with part thickness at the same drawing depth, is first introduced. Further, the drawing depth and process energy are set as the horizontal and vertical coordinates of the map, respectively. Thickness variation data at different drawing depths and process energy are measured and used to build a prediction model by a data interpolation technique to generate a large amount of thickness variation data for map filling. The map is then colored according to the data value, i.e., the smaller the value, the lighter the color, and vice versa. Finally, the quality zone of the map is divided according to the threshold curve of thickness variation. To validate the effectiveness, the map was applied to form a miniaturized car door. The mean absolute percentage error of monitored results was within 9%, showing the high accuracy and effectiveness of the proposed map. The results of applying the map to process control showed a 14.56% reduction in the maximum thinning ratio of the part, which effectively prevents cracking. This work assisted in part quality monitoring and improvement in deep drawing.</p>