Manufacturing: Metal Casting

Introduction

Casting Methods

Online Resources

Metal Casting Techniques - Organic Shell Molding

Shell Molding is probably the earliest, most automated and most rapid of mold (and coremaking) processes.

Resin-bonded silica sand is placed onto a heated pattern, for a predetermined time. Ejector pins enable the mold to be released from the pattern and the entire cycle is completed in seconds depending upon the shell thickness desired. The two halves of the mold, suitably cored, are glued and clamped together prior to the pouring of the metal. Shell molds may be stored for long periods if desired.

Because of pattern costs, this method is best suited to higher volume production. Designers should seek the advice of the foundry to ensure that all the benefits of the process are achieved.

Advantages

• Shell molds may be stored for extended periods of time.
• Good casting detail
• Good dimensional accuracy
• Molds are lightweight.

Disadvantages

• Because the tooling require heat to cure the mold, pattern costs and pattern wear can be higher.
• Energy costs also tend to be higher.
• Material costs tend to be higher than those for green sand molding.