RE:RE: outrageous breakthrough in metal forming technologies..

From: sabine stamm (
Date: Tue Jul 21 1998 - 20:55:16 EEST

Message from:

Sabine Stamm
HOT DOC Productions



Of course, the process by its nature is not a brand new one. In Germany, the
development started 30 years ago.
But now, this tech has its scientific reason. The German way of hydroforming was
the winner of the „German Steel innovation award" and is the theme of numerous

The tech you described, I think that it is the „Flexform" tech.
But it is not a pure stretchforming technology like the one I described. It still
presses (?) the material, that’s the reason for bad wrinkling and springback.
Concerning stereolithography tools and restrictions in aluminum, I will send you
further info in between the next hours.

So long



Neat process but the aircraft industry has been using hydroforming for many

The particular difference and advantage that I see in your process versus
the current process which uses an expandable oil-filled bladder is that
there are some geometries, especially sharp angles and small radii, that the
bladder cannot form well without splitting or shearing the material,
especially when forming aluminum. Also bad wrinkling occurs when trying to
form deep draw parts such as the inlet cap/ring for an engine nacelle. The
water-oil emulsion transmits the force more uniformly over the entire part
surface thus tending to stretch or "iron" the material better than a
conventional bladder-type press. Material springback is still an issue
though and must be considered when creating the tool.

I noticed on your web site that it stated aluminum could be formed, "with
some restrictions." What exactly are these restrictions? Aluminum is a
popular material to use, especially in the aircraft industry, and the
automakers are also increasing their aluminum usage.

I wonder how a stereolithography tool would hold up with exposure to the
water-oil emulsion? We have created some rapid tooling for short run sheet
metal parts (25-50 parts) for use in the bladder-type hydropress.


Glenn Whiteside
Cessna Aircraft Company

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