The housings of the gearboxes in large ships are unique. Casting the housing parts therefore requires specially made casting forms. If the components are manufactured by additive methods, i.e. printed instead of cast, the production of individual moulds is no longer necessary. The weight of the individual parts can also be reduced, as different designs are possible with printing than with casting. For example, cavities or honeycomb structures can be incorporated. The steel gear housing from the 3D printer should therefore weigh a maximum of 10 tons - if it is cast in the conventional way, it will reach a weight of 13 tons.
An enormous printing room is required to produce the gearbox housing parts, which weigh several tons. The 3D printer, which research institutes and companies want to develop together in the project, will be six meters long, three meters wide and one and a half meters high – almost as large as a standard freight container.
When printing the steel housing parts, the researchers at the Laser Zentrum Hannover e.V. (LZH) rely on laser-assisted arc welding. In this additive manufacturing process, steel wire is melted and welded together layer by layer. The research goal is to apply up to five kilograms of steel per hour in this way.
To ensure the quality of the components, engineers at the Institute for Integrated Production in Hanover (IPH) are developing an inline measuring technique. This makes it possible to detect and correct errors during printing. To this end, the printing process is permanently monitored; if necessary, printing parameters are automatically adjusted during the process. If, for example, too much material is applied in one step, less material can be applied in the next step or vice versa. Since some of the material is still hot when printing and some has already cooled down, it is possible that the component may warp due to the shrinkage of the material. "This is a hurdle we want to overcome," says Ake Kriwall, who is responsible for the development of the measurement technology at IPH together with project engineer Dominik Melcher.