13.06.2007

Just 48 hours from idea to shape: fast and cost-efficient manufacturing with Schuler small series and prototypes

When it comes to the manufacturing of complex metal parts, the hydroforming process using active media has firmly established itself on the market. Manufacturers employ this technology above all for the production of chassis, exhaust and structural parts. At the BlechExpo fair in Stuttgart, Schuler is now presenting a series of approaches with which suppliers can leverage the potential of this innovative technology. The main focus is on hydraulic and hydro-mechanical drawing techniques. These processes promise enormous time savings and drastic cost reductions. The declared aim of Schuler’s experts for the production of prototypes is to get from idea to shape in just 48 hours. And in terms of cost, savings of up to 60 percent are thoroughly realistic for the development and fabrication of dies.

The investment costs required to achieve such efficiency gains are comparatively low, as the new processes use the existing machine base. These can be retrofitted by a simple exchange of the pressure chambers, whereby hydraulic machines are used as before. Results from tests carried out together with customers have been impressive so far. For example, Schuler achieved a significant reduction in die fabrication costs for the production of an inner door panel prototype. Instead of producing a special 5-station die for the conventional forming process, there were only costs for the production of the female die and the subsequent laser cutting.

Simple construction, sophisticated technology – Schuler’s turnkey hydroforming offers

The reasons for the significant time gains and enormous savings are to be found mainly in the simpler basic construction of this sophisticated technology. In the field of active media-based metalforming, Schuler offers two different processes. In the hydraulic deep drawing process, parts are formed in a rigid female die with the aid of a pressurized liquid medium. In the case of hydro-mechanical deep drawing, they are formed by using a rigid punch against a pressurized liquid medium. In both cases, the pressure chambers are sealed by a polyurethane cord. Forming with the aid of a fluid medium enables, in particular, the production of spherical geometries in one manufacturing step. In the hydraulic process, the semi-finished products are positioned in the female die between die and part without further significant relative movement. As a result, very high surface qualities can be achieved.
In the case of hydromechanical deep drawing, however, the punch provides the shape and the active medium replaces the female die. When the punch is lowered, the volume reduces and the pressure of the medium ensures that the blank is pressed against the punch. As friction between the blank and drawing radius is significantly lower in this forming process, the hydro-mechanical deep drawing process can achieve much greater drawing depths than with conventional deep drawing. The early positioning of the blank against the punch greatly reduces the danger of second-order wrinkles forming. The hydro-mechanical deep drawing process is therefore particularly well suited to the production of parts which display large, non-supported ring areas at the beginning of the conventional deep drawing process, for example when producing conical parts.

Higher quality, lower environmental impact

These basic technical principles offer considerable advantages over other processes. These include, in particular, the possibility to manufacture extremely complex parts. Whenever parts with convex/concave geometries are required in smaller to medium-size volumes and with extremely high quality requirements regarding shape and surface, active media forming is far superior to other processes. Specific areas of use include the production of parts where design aspects play a key role – such as car body parts and bathroom fittings – or complex structural parts which play a vital role in lightweight construction applications, such as for airplanes. By using a fluid active medium, such parts can be constructed in one draw in future –and thus not require several forming stations. In addition to the reduced load on the material, die costs are also reduced. Moreover, in connection with modern control systems, the range of materials which can be processed is also far greater. This is of particular interest for applications in the aerospace and apparatus construction industries, which use materials that are difficult to process. And finally, experts also point to the environmental aspects, such as the lack of oil-based lubricants which no longer need to be disposed of.

A look into the future

In addition to the presentation of the technical principles and projects already realized, Schuler will also be taking a look into the not-so-distant future at the BlechExpo fair. For example, the new processes can be used for the rapid prototyping of formed parts in the automotive, electrical and construction industries, for the mass manufacturing of niche vehicles or the production of parts with complex geometries. Moreover, the use of alternative active media is also on the agenda of our experts. The first results from using plastic cushions, oil and air open up numerous highly promising possibilities. These tests use cutting-edge research and development findings. Just one year ago, the German Research Foundation completed a program launched in 2000 on active media-based manufacturing processes in the field of metalforming. The 20 institutes involved presented their results in fall 2006 at a colloquium of the Institute of Forming Technology and Lightweight Construction. As a partner of the metalforming industry, Schuler will be among those driving the development. One particular area of focus will be the transfer of quality and know-how from machine construction technology to the new methods and processes.