High-quality sand cores are essential in producing complex, pressure tight aluminum sand and permanent mold castings. Sand cores are used to create internal cavities and external geometry that cannot be formed by the draw of the sand casting pattern or permanent mold tooling.
The tooling used to produce sand cores is referred to as a "core box". The core box, typically made from iron, aluminum or urethane, is used to contain and shape the core sand.
Le Sueur Incorporated produces sand cores in-house using two core making processes:
The Isocure™ Core Making Process
Isocure cores are produced using a "cold-box" core making process. That is, in the Isocure coring making process, no heat is applied to the core box.
An Isocure Core is produced using silica sand mixed with a phenolic urethane resin used as a binding material. This core sand mixture is blown into the core-box. Along with heated air, a vaporized amine gas catalyst is then purged thru the core sand. The vaporized catalyst activates the binding resin which very quickly solidifies the core. For a completely cured core, it is very important that the gas is evenly distributed throughout the core sand. Vents are added strategically in the core-box to aid in the even distribution of the catalyst gas and to reach hard-to-fill areas.
The Shell Core Making Process
Shell Cores are produced using a "hot-box" core making process. There is no catalyst used. Instead, heat is used to activate a resin binder.
A shell core is produced using a sand mixture pre-coated with a resin. The sand mixture is poured or blown into a pre-heated core box. The outside layer of the core is hardened when the sand mixture comes in contact with the heated core box. The core is formed by a thin, hard "shell". Thus the name "Shell Core". The sand on the inside of the core is uncured and can be poured out and reused.
Depending on the application, coatings on cores are used to improve a castings surface finish, improve metal flow, prevent metal penetration of the core sand, prevent "burn-in" and more.
Le Sueur Incorporated specializes in producing dimensionally complex, pressure tight aluminum castings and thermoplastic injection molded components. We offer complete in-house precision machining, finishing and assembly. Please contact us to learn more about our capabilities and how we can best assist with your casting needs!