ThinKing December 2018 – Special nickel molds require less energy to heat up and are 75 percent lighter



Light tools for light parts from the Black Forest.

A modern airplane contains many parts made of carbon fiber reinforced plastic to reduce weight and as a result cut back on fuel consumption. However, even the tools used in construction can be really light: GALVANOFORM produces tools such as nickel molds for fiberglass and carbon fiber plastic parts which use fewer parts and up to 75 percent less material. Thanks to the thinner molds, less energy is required to heat the workpiece during the manufacturing process.

The Development Agency for Lightweighting Baden-Württemberg is presenting this innovation as its ThinKing for December 2018. Leichtbau BW awards this label every month to innovative products and services from the lightweighting sector in Baden-Württemberg.

“About 50 percent of the parts in the current Airbus A350XWB are fiber composite parts. Particularly in the air travel industry, the potential for lightweight technology will be of increasing importance to save kerosene,” says Dr. Christian Feldmer of GALVANOFORM. The company based in Lahr in the Black Forest produces tools such as molds for  carbon fiber and fiberglass components. Their customers are mainly acting in the automotive and aerospace sector. In contrast to other typical raw materials such as steel or iron-nickel alloys, GALVANOFORM is specialized exclusively in using nickel and, as their name already suggests, they build their tools through galvanic electroforming.

Excellent thermal characteristics
“The walls of our tools are only five millimeters thick. Compared to other materials, they are up to four times thinner,” says Feldmer. A huge reduction of up to 75 percent of the amount of required material is not the only positive consequence. “We can create a nickel mold with a very uniform wall thickness which can, for example, give a workpiece a very uniform heat distribution profile in an autoclave”, explains Feldmer. Moreover, nickel has the same thermal expansion coefficient as CFRP. Through precise scaling, CFRP parts can be crafted flawlessly using nickel tools. The biggest advantage however is the saving of energy. “Heating energy is a significant cost factor. In the autoclave, our nickel mold requires notably less energy than molds that are made of other metals, since less mass needs to be heated,” says Feldmer.

Modifying the geometry in post-processing
Nickel tools are normally built according to nominal design data. The first article inspection may reveal that the geometry of the manufactured part does not fall within the required tolerance. “With our tool concept, the nickel mold is attached to a low-stress annealed steel frame. This allows us to adjust the mold later with a coordinate measuring machine. Other metallic tools would have to be reworked mechanically. With our tools, subsequence correction is faster and cheaper,” says Feldmer. This makes it possible to compensate for a potential spring back effect of the part, and this procedure can be used for both flat parts (panels) and double curved or U shaped pieces. A further benefit of nickel as a tool material according to Feldmer is its longevity. The lifetime of one nickel tool is long enough to produce the full number of necessary laminate parts for an airplane.

The tools built by GALVANOFORM have been used to produce the following parts for airplanes: engine claddings, landing flap claddings (flap support, nose cap, trailing edge), doors, landing-gear doors, fins or radar domes. “We can also create undercut areas by inserting separate parts made of stainless steel into the mold which can be removed prior to the ejection of the part from the mold. This way, we can remove the laminate part from the mold without destroying it,” explains Feldmer. For customers in the automotive sector, GALVANOFORM builds molds and tools with leather or customized grains for dashboards.

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