Metalcasting facility shakes out core problems with protein-based binder.

Pride Cast Metals, Cincinnati, was experiencing a problem while shaking sand out of the gas pump swivels it casts. The components are cast in ZA12 zinc alloy, which has a lower pouring temperature than many other metals, meaning the sand cores were not exposed to high enough temperatures for the sand to thermally degrade adequately.

"The temperature wasn't high enough to break down the cores made through a standard process," said Greg Harem, Pride Cast Metals' vice president of manufacturing. "We had to have someone go in and manually remove the core out of these castings because they just didn't break down--they were still rock hard."

That sent Pride Cast Metals, a firm that casts gate valves, nozzles and other components for the petroleum industry, searching for a way to overcome the low production rates and increased costs.

GMBond, a sand binder from Hormel Foods Corp., Austin, Minn., provided the solution. The protein-based binder is mixed with various metal oxide catalysts to accelerate binder breakdown from the heat of the metal. The watersoluble, powdered binder is non-toxic and can be run efficiently in slightly modified coremaking equipment.

The material is pre-made and delivered to Pride Cast Metals, requiring no modifications to be made by the metalcasting-facility. Using the material at a level of 1.5-2%, Pride Cast Metals reduced its core costs by 24% and significantly reduced the time spent moving cores.

The metalcasting facility also noticed another benefit--a reduction in emissions. The binder is made from renewable natural materials, allowing metalcasting facilities to waste significantly less sand and minimize pollution. Testing by the Casting Emission Reduction Program has shown that the binder reduces emissions by more than 90%. Specifically, the binder limits the amount of benzene, naphthalene, phenol, toluene, xylene and formaldehyde.

"There were the obvious time savings and reduced labor to remove the core," Hamm said. "But we also wanted to get involved with this process because it is environmentally friendly. The cores are produced with a protein-based binder system so there aren't as many environmental concerns as with the standard core practices. There aren't any problems with the landfill or disposal of material."

Using pre-made cores molded with GMBond, Pride Cast Metals was able to:

* achieve significantly lower costs per casting;

* significantly reduce the time spent manually removing cores, thereby increasing the number of castings processed;

* maintain good surface finish;

* reduce the amount of toxic emissions during the casting process.

Select No. 001 at www.moderncasting.com/info