The Role of Acid Hardener on the Hardening Characteristics, Collapsibility Performance, and Benchlife of the Warm-Box Sand Cores

• Published in: Archives of foundry engineering 2023-01, Vol.23 (1), p.68-74
• Main Authors: Budavári, I., Hudák, H., Fegyverneki, G.
• Format: Article
• Language: English
• Subjects: Acids; benchlife; Bend strength; bending strength; Castings; collapsibility; Dimensional stability; Foundries; Hardening; Maintenance costs; Mixtures; Sand; sand cores; Shell mold casting; Thermal stability; Thermosetting resins; warm-box; Workability
• ISSN: 2299-2944; 1897-3310; 2299-2944
• DOI: 10.24425/afe.2023.144282

The heat-cured core-making process has been applied for over 60 years to produce molds and cores for different types of castings. The following technologies can be classified into the terminology of “heat-cured coremaking process”: croning-, hot-box -, and warm-box process. The latest technology provides good workability of core mixture, good strength properties, dimensional stability, and good knockout performance of the sand cores. Despite all its advantages, the warm-box technology is less widespread in foundries due to the cost of the high quality thermosetting resin and the maintenance cost of the core box. In this study, the influence of the acid hardener content on the hardening characteristics (bending strength), collapsibility, and the benchlife of the warm-box sand cores were investigated. From the results, it can be said, that within the investigated composition range, increasing the acid hardener content will improve the bending strength of the sand cores. The increased acid hardener content results in higher thermal stability at the beginning of the thermal exposure, and smaller residual bending strength after 15 minutes of thermal loading. The acid hardener level has little effect on the benchlife of the warm-box sand cores, although the sand core mixture is very sensitive to the combined effect of the sand temperature and dwelling time.