Generally, drawing is based on the principle of continuous refinement and equal area. When calculating, the blank area is equal to the drawing? Surface area of parts.

Blank diameter d:

Where f represents the total area of the drawing.

When calculating, there is no middle dimension of material thickness in the calculation of drawing size. When the thickness of the material is below 0.5mm, it can be directly calculated by the outer diameter or the inner diameter.

When calculating the surface of the workpiece, the mouth size should be added with trimming allowance.