Q&A: Sheet Forming

List of Questions

What sheet forming shapes can be done?
What sheet materials can be formed?
What kind of coil is used to form sheet metal?
Why use Magnepress instead of a hydraulic or mechanical press?

For answers to more general questions, click here.

Answers

What sheet forming shapes can be done?

Lots of them. Click here for some examples.

What sheet materials can be formed?

Any highly electrically conductive metal is a great candidate; these include aluminum, low-carbon steel, and copper.  Less conductive metals, such as stainless steel, can be formed using either: 1) more energy, or 2) an aluminum, steel, or copper "driver" to move the stainless steel.  The driver can then be either removed or left on as an integral part of the assembly.

What kind of coil is used to form sheet metal?

To create the required magnetic forces, the coil does not need to be spiraled and cylindrical like a coil spring.  The coil can also be flat, either in the form of a two-dimensional spiral (like an electric stove top) or a two-dimensional zig-zag.  Place the face of the coil on one side of a metal sheet, and a die on the other, and the coil's magnetic forces will form the sheet into the die.

Why use Magnepress instead of a hydraulic or mechanical press?

Lots of reasons.  Here are the most important ones:

1) Aluminum.  In the automotive and other industries, there is interest in using more lightweight materials, such as aluminum.  Unfortunately, despite considerable development effort, adequate formability is not yet available for many aluminum materials.

Magnetic pressing, however, can form aluminum into shapes that usually are impossible to form using conventional metal forming methods without shearing the aluminum.

x_EMF_formability.gif (6675 bytes)Magnetic pressing produces a phenomenon called Hyperplasticity. Hyperplasticity results from inertial stabilization of material failure modes and permits dramatic increases in strain to failure.
Hyperplastic formability of structural aluminum alloys, via magnetic pressing, can cause these alloys to have higher formability than drawing quality steels. This is illustrated in the graph, where data collected from magnetic forming experiments (conducted by researchers at The Ohio State University) on AL6061-T4 are plotted on a traditional forming limit diagram against conventionally formed steel and aluminum sheet.

2) Springback is reduced or eliminated under the dynamic forming conditions achieved with magnetic pressing. This has obvious benefits with respect to product precision and quality.

3) Reduced tooling costs. The magnetic forces act as the "punch" in a punch & die set, so you only need to make the die.

4) Small size and high flexibility of a Magnepress manufacturing cell. While every application is different, Magnepress manufacturing cells are typically dwarfed by a comparable hydraulic press. Magnepress manufacturing cells take up less factory floor space and can generally be moved from place to place with a small motorized forklift. Installation time and changeover time are much shorter than for comparable hydraulic presses.