Knowing About Forming

Here are some ideas and tools specifically tailored for those who have an applied interest in forming things with metal.

Taylan Altan, professor and director, Engineering Research Center for Net Shape Manufacturing (ERC/NSM), The Ohio State University, says that a uniform goal of automakers is to reduce the structural weight of vehicles while retaining the size of said vehicles. . .while adding all sorts of additional gear, like wiring and small motors for the explosion of audio/visual/tactile devices that are now common in cars. So, he suggests, there are two ways to accomplish this slimming.

One is to use light-weight materials, such as aluminum and magnesium. Altan suggests that the utilization of these materials is at higher levels in both Europe and Asia than in the U.S. He cites not only the well-known deployment by Audi of aluminum body panels and structural components for vehicles like the recently introduced A2 (which could probably be more elementarily named the Al 2), but he points out that BMW has long used aluminum for the 500 series rear axle.

While some people might point out that this approach of materials replacement is one that causes an increase in cost as aluminum and magnesium are both more expensive than the ferrous materials that are typically used for things like body and chassis components, the second approach to weight savings that Altan lists is one that is based more on intellectual capital than investment capital: design. He suggests that what some companies are doing is to achieve "stiffness through design."

For example, he points out that if you have a flat piece of material into which you put in a regular pattern of U-shaped bumps (think, in effect, the side view of a piece of corrugated cardboard with the corrugations being part of the bottom portion of the material and gaps where the material rises), that piece is much stiffer than a flat sheet of material. So by doing comparatively simple—and sometimes quite clever—design changes to parts, which may necessitate different types of forming processes, lightening can be realized with comparatively little investment required.

An increasingly common example of achieving stiffness through design, Altan says, is the implementation of tube hydroforming. This technology facilitates a variety of advantages beyond light-weight strength. Among them, Altan notes, are the facts that there is a reduced number of parts needed for assembly (as there is the ability to create complex configurations through the hydroforming process itself such that a single piece can have the topology that would otherwise require the assembly of discrete components), and that the assembly that is needed can be simpler than the traditional approach, especially from the standpoint of tooling requirements (i.e., reduced fixturing).

Altan knows more than a little something about these issues. For one thing, ERC/NSM, which he helped establish in 1986, has organized a consortium of 31 companies that is working on developments in tube hydroforming. And in addition to that process, there are four other metalforming areas that ERC/NSM lists among its core competencies: precision forging; stamping; high performance machining and die/mold manufacturing; education and training.

It is the last-named area that Altan maintains more needs to be done in the U.S. if advances in technology development and implementation are to occur at a rate similar to that in the parts of the world where there are competitive countries (although he does admit, "When U.S. companies decide to do something, they do it," which accounts for the extensive utilization of hydroforming in a comparatively short period of time). Altan suggest that because there is not as much training and education in manufacturing-related engineering in U.S. factories compared to what is the case elsewhere (e.g., he notes that there are plenty of people with PhDs running plants in northern Europe; he points out that the majority of graduate engineering students at places like Ohio State tend to be from other countries—and that many of them return to their home countries) there is a "hidden technology cost." In other words, what we don't know about manufacturing processes can cost us money in the long run.

moving metal
Moving metal with French tooling.

Handle It— Euro Style

French tooling supplier AMG (Grossoeuvre, France)—which works in Europe with companies including Peugeot Citroen, Renault, and Opel, among others—has developed a new series of vacuum suction manipulators for a variety of tasks, including handling stamped parts. Meant for use with a robot or other automated mechanism for spatial manipulation, a key characteristic of this X, Y, Z-axes handling system, which is described as being "less expensive than other systems" (clearly a relative notion), is flexibility: the arms onto which either venturi vacuum cups or two-finger grippers are attached are not welded to the central stock, but fitted so that they can be modified for use with new products.

Parts down one conveyor, usable offal down the other.

Waste Slimming

In some body component stamping operations, usable offal (e.g., the punch outs in window apertures) goes down the scrap chute with operationally useless items like slugs and trimmed material. The parts, of course, are stacked.

Atlas Technologies (Fenton, MI), a supplier of a variety of pressroom automation, has combined its end-of-the-line part stacker with a side stacker that is used to save the usable (i.e., valuable) scrap. In a typical application, there are two indexable belt conveyors that can be oriented where required (e.g., indexed in any of three axes, such as to adjust for the height of the press) to collect the parts or offal. Typically, the offal is dropped from the conveyor into a stacking box located on a pallet; this pallet can be readily shifted out of the stacker so the offal can be removed and later put to good use, not merely sent to the recycler.

Assuring before stamping.

Try First

"In just a short time after installing the two hydraulic high-speed tryout presses, we realized that we can reduce the tryout time of new die sets in our crossbar presses by 50%," says Jeffrey Lukosavich, a manufacturing specialist for Ford Motor Co. He's referring to a set of presses—each rated at 1,980 tons maximum slide capacity—that's been installed at the Ford Chicago Stamping Plant. The presses, said to be the first hydraulic presses in the world that use pre-accelerated drawing cushions in the bolster, are capable of exactly simulating the motions of the three crossbar presses that Ford uses in Chicago—which may not be entirely surprising, given that the tryout presses and the production presses are both supplied by Schuler SMG GmbH & Co. KG (which has its U.S. automotive offices in Dearborn, MI). The maximum displacement force in the cushion is 4,500 kN. A key objective of using the tryout presses is keeping prep work off of the production presses—after all, production presses are an expensive tool to use for setup. As a new die is brought into the facility, it is initially run on the tryout press; in order to facilitate touch-ups and rework, there are a 4,600 x 2,600-mm rolling bolster and a mechanical turnover station for the upper dies. Another benefit of the tryout press is that it permits die spotting (i.e., adjusting the upper and lower dies) prior to stamping operations.

Getting gear ready for DCX minivan underbody production.

DCT Systems for DCX

Productivity now; flexibility for later. That is the evident goal thatDaimlerChrysler (DCX) engineers have for the underbody lines for the 2001 minivans that are being produced in Windsor, Ontario, and St. Louis, MO. Evident because there is the extensive use of robotic equipment to transform sheet metal parts into assembled product.

Take Windsor, for example. There, in an area of approximately 75,000-ft2, systems integrator DCT (Sterling Heights, MI) has put into play 108 robots for welding, material handling, and loading/unloading; eight pedestal-style robots for sealing; and 27 pedestal welders. There are 108 workstations; 134 weld guns are used to produce 797 spot welds on the underbody.

The group of 108 robots were sourced from Nachi Robotics (Novi, MI). This equipment is of two varieties of SA Series, six-axis robots: the model 160, which can handle 160 kg of mass for welding operations, and the low-profile model 200, which can handle as much as 200 kg (and what is notable about this unit is that it is so compact that it can be mounted in places that seem so tight that robot use would be otherwise unthinkable).

Notably, DCT got this program up and running fast: the two underbody lines were executed in just 13 months, compared to the 24 that is typical for programs of this magnitude.