Characterization of No-Bake Phenolic-Isocyanate and Furanic Binders in Different Base Metal Casting Sands

A. Materials

For the development of this research, types of silica sands from two different suppliers (Sierra Central and Sibelco) is uses. Another, corundum base sand from a third supplier (Cast Ball from Mineração Curimbaba) is also studied. A summary of the main characteristics of these base sand is presented in Table 1. On the other hand, phenolic-urethane (PUNB) and furanic resin (FA) are the chemical binders applied in the research due to their widespread use.

The molding mixtures to be evaluated are shown in Table 2. In the table the abbreviation PUNB means Phenolic-urethane No Bake System and the abbreviation FA means Furan Resin. Characteristics such as grain size, amount of fine powder, moisture content, pH and LOI, were determined based on procedures given in the Mold & Core Test Handbook from AFS.

The classification of the grain shape is carried out based on Figures 1, 2 and 3. According to the AFS 1107-12-S procedure, the shape of the different base sands is as follows: Sibelco silica sand and Sierra Central silica sand have a subangular shape and Corundum Cast Ball has a rounded shape.

Figure 1.

Corundum Cast Ball, magnification x20.

Figure 2.

Silica sand Sierra Central, magnification x20.

Figure 3.

Silica sand Sibelco, magnification x20.