Machine Design

How-to, in-depth technical articles for machine design engineers

Hydraulics & Pneumatics

For design and manufacturing engineers involved in buying or specifying fluid power components and systems.


International news and technology for marine/offshore operations around the world.

Laser Focus World

Semiconductors, medical equipment, lasers, optics and aviation and aerospace.

more free magazines

In drawing, a blank of sheet metal is restrained at the edges, and the middle section is forced by a punch into a die to stretch the metal into a cup shaped drawn part. This drawn part can be circular, rectangular or just about any cross-section.

Drawing can be either shallow or deep depending on the amount of deformation. Shallow drawing is used to describe the process where the depth of draw is less than the smallest dimension of the opening; otherwise, it is considered deep drawing.

Drawing leads to wrinkling and puckering at the edge where the sheet metal is clamped. This is usually removed by a separate trimming operation.

Design Considerations
 • Round shapes (cylinders) are easiest to draw. Square shapes can also be drawn if the inside and outside radiuses are at least 6 X stock thickness. Other shapes can be produced at the cost of complexity of tooling and part costs.

The corner radiuses can be reduced further by successive drawing operations, provided there is sufficient height for the draw.
Perpendicularity can be held to ±1º, flatness can be held to 0.3%. This can be improved by performing extra operations.