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THE SAND PROCESS

HOW IT WORKS The Sand Casting ( Green Sand ) molding process utilizes a cope ( top half ) and drag ( bottom half ) flask set-up. The mold consists of sand, ( usually silica ), clay and water. When the water is added it develops the bonding characteristics of the clay, which binds the sand grains together. When applying pressure to the mold material it can be compacted arounda pattern, which is either made of metal or wood, to produce a mold having sufficient rigidity to enable metal to be poured into it to produce a casting. The process also uses coring to create cavities inside the casting. After the casting is poured and has cooled the core is removed.

The material costs for the process are low and the sand casting process is exceptionally flexible. A number ofmetals can be used for castings in sizes from ounces to many thousand pounds. The mold material is reclaimable, with between 90 and 95% of the sand being recycled, although new sand and additions are required to make up for the discarded loss. These features, combined with the relative ease of mold production, have ensured that the green sand molding process has remained as the principal method bywhich castings are produced.

THE SAND
The sand used for green sand molding is critical and determines the favorable or unfavorable outcome of the casting. It controls the tolerances, surface finish and the repeatability while in production. Remembering that the tolerances on sand castings are usually wider than the other casting methods. The sand must exhibit the following characteristics:FLOWABILITY: The ability to pack tightly around the pattern. PLASTIC DEFORMATION: Have the ability to deform slightly without cracking so that the pattern
can be withdrawn.

GREEN STRENGTH: Have the ability to support its own weight when stripped from the pattern, and also withstand pressure of molten metal when the mold is cast. PERMEABILITY: This allows the gases and steam to escape from themold during casting.
All of these requirements are dependent on the amount of active clay present and on the water content of the mixture.

For more information or a competitive quote please contact:

TOM CLARK McCann Sales, Inc. Ph: 207-439-3747 E-mail: tclark@maine.rr.com

SAND CASTING BENEFITS
Least Expensive Casting Process Castings can be up to Several Tons Less Expensive thanMachining Shapes from Bar Stock Can Cast Intricate Shapes Can be Used with Most Pourable Metals and Alloys

SHRINKAGE ALLOWANCE FOR METALS COMMONLY USED IN SAND CASTING
Gray Iron Ductile Iron Mallable Iron White Iron Aluminum Alloys Magnesium Alloys .83 – 1.3 .83 – 1.3 .78 – 1.3 2.1 1.3 1.3

For more information or a competitive quote please contact:

TOM CLARK McCann Sales, Inc. Ph:207-439-3747 E-mail: tclark@maine.rr.com

THE SAND PROCESS

The pattern first makes an impression in the cope and drag. The impression created includes the gating system as

The cope and drag are then combined and are ready to accept the metal.

The metal is heated and prepared metallurgically. It is transferred to a crucible just before pouring.

The molten metal is then poured into the mold.The part is allowed to sit and cool. Once cooled the casting and gating system are removed from the mold and the sand is recycled.

The casting is then sent to the finishing department where any remains of the gates are ground off.

The part is the cleaned and ready to ship.

For more information or a competitive quote please contact:

TOM CLARK McCann Sales, Inc. Ph: 207-439-3747 E-mail:tclark@maine.rr.com

SAND CASTING

This picture shows the cross section of a sand casting mold.

DEFINITIONS
1. POURING CUP: This is where the metal is poured into the mold. 2. SPRUE: The vertical channel from the top of the mold to the gating and riser system. Also, a generic term used to cover all gates, runners and risers. 3. RUNNER: The portion of the gate assembly that connects the...
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