September 2008 Edition

FDM

Possibilities abound with fused deposition modeling

BMW plant uses technology to build tools for assembly, testing

In the jigs and fixtures department at BMW AG, Regensberg, an FDM system is used to rapid manufacture assembly tools such as these.

Like many other manufacturers, BMW makes use of rapid prototyping to develop products — and at the BMW AG plant in Regensburg, Germany, FDM (fused deposition modeling) continues to be an important component in vehicle design prototyping.

But moving beyond prototyping, BMW is extending the application of FDM to other areas and functions, including direct digital manufacturing.

The plant’s department of jigs and fixtures uses FDM by Stratasys Inc. of Eden Prairie, MN, to build hand tools for automobile assembly and testing.

"BMW has determined that the FDM process can be an alternative to the conventional metal-cutting manufacturing methods such as milling, turning, and boring," says engineer Günter Schmid.

Schmid and fellow engineer Ulrich Eidenschink believe that the financial advantages include cost reductions in engineering documentation, warehousing, and manufacturing.

‘FDM is taking on increasing importance as an alternative manufacturing method for components made in small numbers.’
— Günter Schmid

For hand-held devices used on the assembly line, engineers have discovered that there are even greater advantages that arise from the design freedom that FDM offers. Capitalizing on the elimination of constraints, Schmid and Eidenschink employ FDM to make ergonomically designed assembly aids that perform better than conventionally made tools.

Thanks to a tool created for attaching bumper supports, this BMW exhibits the classic look of the automobile.

To improve productivity, worker comfort, ease-of-use, and process repeatability, the plant uses FDM to enhance the ergonomics of its hand-held assembly devices. The freedom of design allows engineers to create configurations that improve handling, reduce weight, and improve balance.

"The tool designs we create often cannot be matched by machined or molded parts," says Schmid.

In one example, BMW reduced the weight of a device by 72 percent with a sparse-fill build technique. Replacing the solid core with internal ribs cut 1.3kg (2.9lbs) from the device.

"This may not seem like much, but when a worker uses the tool hundreds of times in a shift, it makes a big difference," says Schmid.

Another advantage of direct digital manufacturing is improved functionality. Since the additive process can easily produce organic shapes that sweep and flow, the tool designers can maximize performance while improving ergonomic and handling characteristics.

"The layered FDM manufacturing process is well-suited for the production of complex bodies that, when using conventional metal-cutting processes, would be very difficult and costly to produce," says Eidenschink.

An example is a tool created for attaching bumper supports, which features a convoluted tube that bends around obstructions and places fixturing magnets exactly where needed.

The jigs and fixtures department has developed a simple flow chart to determine when FDM is a fitting option. The criteria are temperature, chemical exposure, precision, and mechanical load. With FDM’s ABS material, which the engineers find comparable to polyamide (PA 6), many tools for vehicle assembly satisfy the criteria. For those that do, designers can create devices that capitalize on all the advantages of the additive process.

 Stratasys Inc.

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