Francis Impeller

In the case of the francis runner, the foundry e-mailed the CAD data to Augsburg as usual. Following a review, the data set was transferred to the system, where the molds were created in just a few hours using Kerphalit – a molding material particularly suited for iron and steel casting – in 0.3 mm thin layers. 

After the build process, excess sand was removed from the parts, which were cleaned with compressed air and subsequently shipped to the foundry (Fig. 3). At the foundry, the molds were individually blackened, assembled and cast at 1650°C using corrosion-resistant stainless steel.

 "The voxeljet method is predestined for the production of prototypes, since it does away with the need to create expensive models using conventional methods, which require the production of tools, molds and core boxes," explains Paul Stadler, Avor Sand Casting Manager at Wolfensberger. This saves a lot of costs, since design data is often adjusted and changed during the development and testing process for the runners. This in turn requires new models to be built, which is time-consuming and expensive using conventional methods. With voxeljet, changes can be made virtually with one mouse click, and the computer-controlled production of a new mold can begin.

Another advantage of this method is the design scope that it offers. With conventional core building methods, a variety of different parts must frequently be assembled into the desired end product. voxeljet's method, on the other hand, makes it possible to produce large parts in one piece, and also allows for the addition of undercuts. 

This has a very positive effect on the accuracy of the cast part and reduces cleaning requirements, since the removal of the core separations does not result in any casting defects. Top quality at lower costs and very short lead-times are the guarantee that both companies will continue their customer-oriented and productive cooperative relationship.

Technical data

SAND MOLD
Total size                2,203 x 1,400 x 980 mm 
Weight201 kg
Individual pieces2
Material Kerphalit
Layer thickness0.3 mm
Lead time5 days
Build time40 hours