Rubber Plaster Mold Casting


Rubber-plaster mold casting, also known as “plaster casting” or “rubber mold casting,” is a well-established metal casting process that combines the advantages of rubber patterns with plaster molds to produce intricate and detailed metal parts. This technique has been used for centuries and continues to find applications in various industries due to its versatility, cost-effectiveness, and ability to produce high-quality castings.

The Rubber-Plaster Mold Casting Process:

Step 1: Pattern Creation The casting process commences with the creation of a master pattern. Skilled artisans or modern manufacturing methods produce this pattern using rubber. The rubber pattern offers flexibility and allows for capturing complex details of the desired metal part.

Step 2: Mold Creation The rubber pattern is then used to create a mold made of plaster. The rubber pattern is pressed into the plaster, leaving an impression of the desired metal part. The plaster mold sets and hardens, forming a negative cavity that mirrors the rubber pattern.

Step 3: Removing the Rubber Pattern Once the plaster mold has fully set, the rubber pattern is removed, leaving behind a void in the mold that corresponds to the desired metal part.

Step 4: Moisture Removal The plaster mold is heated to a specific temperature to remove any remaining moisture. This step ensures that the mold is dry and ready to receive the molten metal without any issues.

Step 5: Metal Casting With the plaster mold prepared and dry, molten metal is poured into the mold. The metal fills the cavity previously occupied by the rubber pattern, taking its shape.

Step 6: Cooling and Solidification The molten metal cools and solidifies within the plaster mold. During this phase, the metal takes on the intricate details and dimensions of the original rubber pattern.

Step 7: Mold Breakout and Finishing Once the metal has solidified, the plaster mold is carefully broken away, revealing the newly cast metal part. The casting may require additional finishing processes, such as grinding, polishing, or machining, to achieve the desired surface quality and dimensional accuracy.

Advantages of Rubber-Plaster Mold Casting:

  1. Intricate Detailing: The rubber pattern allows for capturing intricate and fine details in the final metal casting, making it ideal for producing complex parts.
  2. Cost-Effective: This casting method is cost-effective for small to medium production runs, making it suitable for custom-designed parts and limited quantities.
  3. Versatility: Rubber-plaster mold casting can be used with a wide range of metals, including aluminum, bronze, brass, and various alloys.
  4. Dimensional Accuracy: The use of a rubber pattern ensures high dimensional precision and consistency in the final metal castings.
  5. Reduced Shrinkage: The rubber pattern compensates for metal shrinkage during solidification, resulting in precise final dimensions.

Applications of Rubber-Plaster Mold Casting:

  1. Artistic Metalwork: The process is widely used in creating custom metal sculptures and artistic pieces.
  2. Jewelry: Rubber-plaster mold casting is employed in jewelry making to produce intricate and unique designs.
  3. Industrial Components: It finds applications in manufacturing complex metal components used in various industries, including aerospace and automotive.


A. L. Johnson Company, RPM Process – How Rubber Plaster Mold Castings are Made

USG Industrial and Specialty Solutions: Drying Plaster Casts