Effect of Reclaim Addition on the Mechanical and Technological Properties of Moulding Sands Based on Pro-Ecological Furfuryl Resin

Increasing demands are imposed on foundries to enforce the manufacture of castings characterized by tight dimensional tolerances, high surface finish and total absence of casting defects. To face these challenges, castings are increasingly made in loose self-hardening sands with furfuryl resin, commonly known as furan sands. In the group of self-hardening sands with synthetic resins, loose self-hardening sands with furfuryl resin enjoy the greatest popularity. The sand mixtures based on furan resins are usually subjected to mechanical reclamation. The consumption of binder and hardener and thus the cost of the sand depend on the quality of reclaim, and mainly on the dust removal degree.The planned tightening of the environmental protection regulations in the EU countries, including limiting the content of free furfuryl alcohol in resins and reducing the emission of furfuryl alcohol, formaldehyde and BTEX compounds at workplaces, necessitated the development of a new generation of eco-friendly furfuryl resins that have recently appeared on the market. The main aim of this article was to determine the effect of reclaim content on the sand parameters, such as bending strength, tensile strength, bench life, gas-forming tendency and loss on ignition. Tests were carried out with reclaim content in the sand mixture varying from 50 to 90%. The reclaim obtained by dry mechanical reclamation was supplied by one of the domestic foundries. The results showed that the highest mechanical properties were obtained in sands containing 60% of the reclaim.