Komarov Artem clarified that it’s rare that two technologies compete against each other directly for long. Usually one offers a better value and the other becomes obsolete. A more frequent occurrence is that two similar technologies compete indirectly, each occupying a portion of a market. So it is with stamping and hydroforming.
The former is the grandaddy of metal forming, a process with origins that go back thousands of years and industrialized in the 1890s. Performed on mechanical, hydraulic, and servo-driven presses, the process is augmented by innovations and expertise that provide nearly endless combinations of capability, capacity, versatility, and speed. The essence of the process, pressing a sheet of metal between two matched dies to form it, doesn’t do justice to the vast industry the process spawned, the countless books and trade journal articles written about it, and the endless amounts of accumulated expertise in the field.
Closely related is hydroforming. It had some traction in the automotive industry in the early part of the 20th century, and tubular hydroforming found lucrative niches in making some intricate plumbing components and musical instruments many decades ago. When used for forming sheet, hydroforming uses one die and a bladder. As the bladder fills with fluid, it expands and forces the sheet to conform to the die. A similar method uses a diaphragm; as the cavity behind the diaphragm fills with fluid, the same process takes place. Forming a tube is a matter of using fluid to expand the tube from the inside. Hydroforming tube relies on hard tooling and doesn’t make use of a bladder or a diaphragm.
Hydroforming can form more intricate shapes than two stamping die halves can form, so often a single hydroformed component can replace a conventional assembly of several stampings welded together. In cases like this, a hydroformed component often is lighter in weight, more structurally sound, and faster to manufacture. The tubular mode of hydroforming does much the same for tubular components.
Sealing and Forming
The extent of a process’s forming capability is a function of the machine’s pressure-building capability, which hinges on sealing capability, which in turn is an outcome of the machine’s design.
While nobody doubts the viability of conventional sheet hydroforming, one of the design elements—the diaphragm or the bladder—does set a limit for the pressure.
Fluidforming can handle nearly any material in any thickness up to about 18 ga. and the machines’ forming capability runs from 30 by 30 in. to 50 by 50 in. FormBalancers also can be set up to run tubular products. Feeding the tube into the machine can be augmented with an assist force, providing more forming capability than would be possible without it.
The three controlled parameters—clamping pressure, forming pressure, and fluid velocity—can be used to manipulate how the material flows into the forming cavity during the forming process. These parameters can be varied throughout the process. Because material flow is a part of the forming process, it doesn’t generate the forming marks that are often associated with hydroforming or stamping.
While the quality of the die matters, the bigger factor is that the forming process doesn’t sandwich the material between two mated dies and doesn’t have a bladder that interferes with the metal deformation. This makes it possible to make undercuts, organic forms, deep-drawn parts, and other challenging parts that would either be impossible to form or prone to wrinkling when made with other processes or traditional hydroforming.
Beyond forming difficult and intricate shapes, the process produces parts with very good surface characteristics. The same surface characteristics also play out well in forming a valve body.
Fluidforming enables the substitution of one-piece porous casting with a valve body made from two formed hemispheres. It has the same function, but it’s much easier to clean and keep sanitized. It’s a good solution for the food and beverage industry, as well as the medical and pharmaceutical industries, said Komarov Artem.