B3b: Applying 3D Sand Printing, an Indirect Additive Manufacturing Technology, to Casting of Monoblock Impellers

See how application of a new technology — 3D sand printing, an indirect additive manufacturing technology — is having a major impact in the production of impellers for Francis turbines or for pumped storage hydro casted as a single piece: a so-called monoblock.

Applying printed cores leads to improved risk control throughout the complete subsequent production, substituting steps and thus shortening lead-time as well as an improved carbon footprint. By reducing the need for inspections and eliminating wooden patterns, a foundry can increase efficiency, lower costs, and enable original equipment manufacturers to meet customer demands faster and with greater precision.

Could this be a paradigm shift for future projects?

BACKGROUND on Monoblock Impellers
Until about 30 years ago, the production of impellers for Francis turbines or for pumped storage hydro casted as a single piece — a so-called monoblock — was common and seen as the supreme discipline of steel casting.
Although it is one of the oldest but still most energy-efficient methods of manufacturing turbine components, in this monoblock production technique, the level of automation is comparatively low. The high proportion of manual work was at odds with a risk-averse industry where quality and safety are paramount.
However, due to increased quality requirements, inferior supplies, and the availability of evolving methods such as CNC machining or welding solutions changed the industry’s sourcing strategy.
It was not until recent years that original equipment manufacturers (OEMs) regained confidence in steel castings.
What happened?
Over the past 20 years, the steel foundry industry has undergone significant technological advancements and improvements. These include the implementation of advanced computer-aided design and simulation tools, and the use of improved alloys and heat treatments. These advancements have resulted in increased efficiency, higher precision, and improved quality control, making steel foundries more competitive in the global market.
voestalpine Foundry Group, in particular, shifted in the recent years the focus on automation of manufacturing processes, like moulding and welding. The investment into 3D sand printing, an indirect additive manufacturing technology, has a major impact in the production of monoblock impellers.