The foundry that produced this hydraulic monoblock for the construction industry converted the process from green sand casting with traditional core tooling to green sand with 3D printed cores. 

By consolidating over 14 cores into a complex, single-piece core, core assembly labor costs as well as the costs associated with tooling design, fabrication, storage, and maintenance were all eliminated––for the life of the part––using the toolingless 3D printed sand process as opposed to conventional individual blown cores.

The absence of tooling-related constraints afforded by 3D printing gave part designers freedom to add features into the core, which reduced the amount of machining required. 

Typically, outer simple shapes can be made using the conventional green sand process––but combining it with 3D printed core consolidation is a hybrid approach that’s more cost effective. Printing the consolidated core drastically reduced lead time and offers the potential of lightweighting, tighter dimensional tolerances, and better cored surface finish. 

Complex designs can be turned into reality with feature and part consolidations otherwise impossible a with conventional tooling approach.

Complex cored geometry with tighter true positional dimensional tolerances. 

•    The toolingless 3D printed sand casting process allows any complex core shapes to be made,  regardless of their location and orientation with respect to the parting plane or any drafting constraints typically experienced with conventional sand casting process and blown cores made using core boxes.

•    Core consolidation along with the redesign of the casting’s wall thickness due to much better dimensional tolerances (lower vales) compared to conventional sand casting, will result into lighter, near net shaped castings.
Freedom with cored holes and pockets in low stress areas. 

•    Keeping generic castability and fluidity considerations, design engineers have full freedom with the placement of features including ribs, pockets, cored holes, draft, thin to thick transition, and more with 3DP, resulting in a robust optimum design with lower weights.

•    Low or zero stress areas can be further lightened up by cored holes and pockets.   Process parameters as well as gating and risering design for the interconnected core structure needs to be validated by simulation to ensure the liquid metal fills properly and solidifies to get the desired soundness, properties and quality. 

Generous fillet, radii and transitions for better cast component 

•    When it comes to the 3D printed sand additive manufacturing process, the core orientation with respect to the build-up direction (Z-axis) is important to reduce the layering or staircasing effect for better surface finish. 3D printed cores can be coated using conventional mold and core refractory coatings to further improve the surface finish and typically, requires extra venting for out gassing.

•    Complex casting shapes make the rigging design challenging to produce 3D printed tooling-free sand castings with desired quality; however, casting process modeling is found to be very valuable to validate the rigging scenarios and process conditions, predicting the casting quality before printing the cores with higher degree of confidence, which is very crucial for the toolingless process!