Additive Cuts Defects, Improves Surface Qualities

Jan. 21, 2011
deveiner for no-bake and resin-coated sand mold and core applications.
Two samples of an identical casting, one produced using 4.5% SpherOX (top), and one produced without the synthetic sand additive (below).

Sand casting foundries need to overcome the quality problems inherent to the process, veining for example, and other common defects that reduce overall productivity. Chesapeake Specialty Products produces environmentally friendly metallic abrasive and iron-oxide products that improve finished product quality, thereby reducing waste in the sand casting process, but also minimize emissions and consumers’ costs.

Chesapeake has been developing and producing iron oxides and recyclable metallic abrasive products more than 20 years. Its SphereOX® product is a deveiner for no-bake and resin-coated sand mold and core applications. It also addresses penetration, pinholes, and lustrous carbon casting defects.

SphereOX is a synthetic spherical foundry sand additive that the developer indicates is consistently purer than natural oxides. The production process results in a predominantly spherical shape of high-purity iron oxide, according to Chesapeake.

No binders, glues, or other ingredients are added to SphereOX that might increase surface area, or add hydrocarbons or other volatiles that might generate gas during casting. When it’s heated, SphereOX produces a gain on ignition of approximately 10%, making it effective as “a gas scavenger,” and thus effectively reducing many of the common sand-casting quality defects.

“When used as an additive in foundry cores/molds SphereOX significantly reduces surface defects and improves the quality of the castings. It has excellent flow properties and requires less resin to achieve the required mold core bond strength,” according to the developer. It is typically added to no-bake foundry molding sand systems as an additive at 2-8% by weight to improve the surface finish of iron or steel castings, and to eliminate veining and mold penetration, burn-in and burn-on, as well as pinholes from entrapped gas.

Foundries that use SpherOX will reduce their use of gas-generating resins, while improving mold strength, according to Chesapeake. By using less binder, they reduce consumable costs. And, because the better quality castings require less cleaning, saving time and money, it decreases the volume of dust produced, for a cleaner workplace.

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