How to Calculate Number of Cavity in Injection Molding?

What Is Cavity in Injection Molding?

In injection molding, a cavity is a hollow space or void within a mold that is filled with molten plastic resin to produce a specific shape or part. The cavity is typically designed to match the desired shape of the final product, and it may have various features such as ribs, bosses, and threads that are used to enhance the functionality of the part.

During the injection molding process, the molten plastic resin is injected into the cavity under high pressure, where it cools and solidifies to form the final part. The design and construction of the cavity is critical to ensuring that the part is produced accurately and efficiently, and that it meets the required specifications for strength, durability, and appearance.

How to Calculate Number of Cavity in Injection Molding?

The calculation of the cavity number in injection molding depends on several factors such as the size and complexity of the part being produced, the size of the injection molding machine, and the desired production rate.

Here are the steps to calculate the cavity number in injection molding:

Determine the size of the injection molding machine that will be used for the production. This will give you the maximum mold base size that can be accommodated.

Determine the size of the part being produced. This will help you determine the base size required of the injection molds for sale.

Determine the desired production rate, which is usually measured in parts per hour.

Calculate the projected cycle time for each part. This is the amount of time required to complete one cycle of the injection molding process for one part.

Calculate the total production time required by multiplying the projected cycle time by the desired production rate.

Calculate cavity number in injection molding required by dividing the total production time by the total time required to produce one part in a single cavity mold.

For example, if the total production time required is 10 hours, and the total time required to produce one part in a single cavity mold is 1 minute, then the number of cavities required would be 600 (10 hours x 60 minutes per hour / 1 minute per part per cavity).

Keep in mind that the number of cavities that can be used in a mold will also depend on other factors such as the material being used and the part design. It is important to work with an experienced injection molding professional to ensure that the mold design is optimized for production efficiency and quality.

What Is the Difference Between Cavity and Core in Injection Molding？

In injection molding, the cavity and core are two key components of the mold that work together to form the final part. They serve distinct but complementary roles in shaping the part and determining its functionality. The mold is made up of two primary halves: the cavity side and the core side. These two elements define both the external and internal features of the part, ensuring that the finished product meets its design specifications.

1. Cavity:

• Definition

The cavity is the hollow space inside the mold where the molten plastic is injected to form the outer shape of the part. It creates the external features and surface details of the component. The core is the part of the mold that creates the internal features or voids of the molded part. It forms the inside of the part and can create complex geometries, such as holes, recesses, or undercuts.

• Position

Cavity is typically located on the parting side of the mold, which is where the mold splits to allow for the part to be ejected. The core is typically positioned on the opposite side of the cavity and works in conjunction with it. It often contains features like cooling channels and can be removable or fixed, depending on the mold design.

• Function

The cavity holds the injected material as it cools and solidifies, giving the part its shape. The cavity determines the exterior surface features of the final product. The core shapes the interior of the part, ensuring that internal cavities, holes, or intricate designs are formed during the injection process.

2. Key Differences:

• Purpose: The cavity forms the outer shape of the part, while the core forms the inner features.

• Location: The cavity is located on the external side of the mold, and the core is positioned on the internal side.

• Shape: The cavity is typically shaped to the external geometry, whereas the core defines the internal spaces or features.