Shell Molding Process: Principle and Pros and Cons

Shell Molding Principle

Shell molding is a type of sand casting that uses thin shells instead of sand. Shells are made by coating a mold frame with materials such as gypsum, pearlite, and skimmed milk. Shells are typically 3-5 mm thick and have a strong bonding layer of resin inside.

The shell molding process proceeds in the following steps:

1. Prepare the mold frame.
2. Apply the shell coating agent to the mold frame.
3. Harden the shell.
4. Separate the shell from the mold frame.
5. Pour molten metal into the mold frame.

Shell Molding Pros

Shell molding has the following advantages:

• High precision: Shells are thinner and stronger than sand, so the inner surface of the mold is very smooth and precise. Therefore, the surface quality of the cast product is excellent.
• High productivity: Shells have a shorter mold making time than sand casting, and the mold life is also longer, so productivity is high.
• Low cost: Shells are more cost-effective than sand casting.

Shell Molding Cons

Shell molding has the following disadvantages:

• Mold making skills are required: Skilled skills are required to make shell molds.
• The mold is easy to break: Shells are stronger than sand, but they are still easy to break. Therefore, handling should be done with care.
• The casting process is complex: Shell molding is more complex than sand casting.

Applications of Shell Molding

Shell molding is used mainly in the production of precision products in industries such as automobiles, aircraft, and electronic devices. Representative application areas include the following:

• Engine parts
• Body parts
• Aircraft parts
• Electronic parts
• Medical devices

Shell molding is a casting method with the advantages of high precision, high productivity, and low cost. Due to these advantages, it is widely used in various fields.