Choose Your Casting Method
Below are brief descriptions of the capabilities of The Eagle Group, including several different methods of metal casting, as well as CNC machining. We hope to help you choose the metal casting method that’s right for your project. Take a look at our resources below, and if you have any questions click here to contact us any time.
Click here to download our comprehensive Shell Molding Process Guide, including an overview of different methods of metal casting.
Click here to download our Buyer’s Guide to Purchasing Raw and Machined Cast Products, also including a summary of different metal casting methods.
Shell mold process
Offered by Eagle Alloy, the shell mold process is the industry standard for medium to high volume, commercial-grade casting projects. For a better look at how the process works, we offer a video animation and a comprehensive white paper on shell mold casting.
Thermally bonded sand is applied to the surface of a pre-heated pattern usually made of cast iron or steel. The “baked” mold is lifted from the pattern in halves. The halves are glued together, assisted by precise locating features to avoid shifting. The Shell process offers tolerances of +/-.030” on dimensions 6” or less and a surface finish around 200 – 250 RMS. Click here for a complete description of available tolerances, radii, fillets and other design considerations.
Advantages: good casting detail, excellent repeatability, very productive, less machine stock required than in greensand or no-bake processes, competitive pound-prices, very short production lead times.
Disadvantages: tooling prices higher than some other processes.
Lost-wax investment process
Eagle Precision Cast Parts uses this process exclusively. Wax is injected into an aluminum die to create a wax “pattern”. These wax patterns are then assembled onto a “tree” which is repeatedly dipped in a ceramic slurry that, after drying, hardens into a mold. The wax is melted out, the mold is preheated and the metal is poured in. The resulting casting has an excellent surface finish of around 125 RMS, crisp lettering and minimal machine stock. This process is perfect for highly visible parts or replacing machining with cast features. Tolerances can be held to +/-.005” in most cases.
Advantages: excellent overall appearance, machining reduced or eliminated, can cast very thin walls, good for prototypes, economical tooling costs.
Disadvantages: higher pound-prices.
Permanent Mold (gravity pour)
The term “permanent mold” describes a mold that can be used repeatedly, in contrast to sand-molds that must be destroyed to remove the casting. This is only one of the casting methods offered by Eagle Aluminum Cast Products. Permanent molding is desired by those requiring an aluminum casting with good density and superior mechanical properties. Castings made with this method are much more dimensionally accurate and repeatable than those made using sand methods. This reduces or eliminates much of the machining that may be required.
Advantages: very repeatable, sound density, can utilize cores in the casting design, short lead times, excellent appearance, tight tolerances, perfect for high volume.
Disadvantages: tooling prices higher than those used in sand processes.
Along with permanent molding, Eagle Aluminum Cast Products offers castings made with the greensand molding method. Greensand molding is the most diversified molding method in use today. Loose sand is mixed with a bonding agent and moisture then compacted onto a pattern. After both halves of the mold are made they are positioned together and filled with molten aluminum. Eagle Aluminum’s expertise makes us one of the few capable of casting very large castings with very thin sections.
Advantages: low pattern costs, speed to market, not quantity-sensitive, can utilize cores in the casting design.
Disadvantages: not suitable for smaller parts, “grainier” surface finish than perm mold.
Eagle CNC Technologies utilizes the latest in machining technologies and has experience machining all types of casting and wrought materials. Our services are mainly utilized by, but are not restricted to, the Eagle Group. Our commitment to maintaining available capacity means our facility list is constantly expanding with the latest and greatest machines available. Contact us to discuss your next machining project.