FH-Cast: Mold production with 3D-printed positives

Optimize extraction

The basis of the development of the "FH-Cast" process is the 3D printing of a plastic positive mould in connection with the production of the casting mould. The focus here is on the use of cost-effective 3D printers using the fused filament fabrication process. A major challenge of the process is the removal of the embedded positive mould from the cured moulding material. In order to optimise the chemical or thermal dissolution of the moulded material, different polymers were evaluated for use as positive material.

Development of a test geometry

The best results were achieved with low-viscosity PLA. Both quartz sand and an investment casting compound were tested as moulding materials. For the bonded quartz sand, the melting process was optimized to ensure the stability of the sand mold. In order to test and compare the two moulding materials and the suitability of the process for different casting alloys, a test geometry was developed. This includes cylinders with different wall thicknesses, different bores (diameter/length ratio 1:1 to 1:5) as well as features for assessing the casting accuracy. This geometry was cast with zinc and  various AlSi alloys as well as brass using gravity casting.

Suitability of the "FH-Cast" procedure

Interesting and promising is the developed "FH-Cast"-method both for the prototype production and for the production of test pieces. In particular, the process on a laboratory scale is also suitable for training purposes in the foundry industry using the latest technologies.