How Do You Create a Core & Cavity Using 3D Model for Injection Molding?

Creating a Core & Cavity using 3D Model

Injection molding is a cornerstone of modern manufacturing. At the heart of this process lies the mold die, which shapes molten plastic into precise, repeatable parts using Core and Cavity using 3D Model techniques.

Die:

• A mold die consists of two or more parts that come together to form a cavity (a hollow space) into which material is injected or pressed.
• Once the material cools or hardens, the mold is opened, and the finished part is ejected.

Components:

• Core and Cavity: The two main parts that shape the product.
  
• Sprue, Runners, Gates: Channels that guide material into the cavity.
  
• Ejector Pins: Push the finished part out of the mold.
  
• Cooling Channels: Circulate water or coolant to solidify the material quickly.
  

Core:

• The male half that forms internal surfaces.
• A mold design component that forms the opposite side of a molded part, creating the inner shape or cavity using 3D model.
  

Cavity:

• The female half that forms the external surfaces.
• Cavity is used to create a cavity using 3D model within a mold base by effectively subtracting the shape of a design part from it.

When closed, these two halves form the complete geometry of the part. After the part cools, the mold opens, and ejector systems push the part out.

Creating a Part:

• Consider a part as been created as shown below.
• Which has been created as a solid model.
• Maintain uniform wall thickness.
• Add draft angles to vertical walls to aid in mold release.
  
  
  
  

  Figure 1
  
  

Draft Analysis:

• Use SOLIDWORKS Draft Analysis tool to evaluate part geometry.
• Go to Mold Tools > Draft Analysis.
• Define the pull direction (ejection direction).
• Review color-coded feedback for draft quality.
  
  
  
  

  Figure 2
  
  

Create the Parting Line:

• Select Parting Line in the Mold Tools tab.
• Choose edges that will split the mold.
• Generates the parting line based on geometry and pull direction.
  
  
  
  Figure 3
  
  

Shut-Off and Parting Surfaces:

• A surface patch created to close a through-hole, essentially sealing the hole's opening.
• Parting Surfaces extend from the parting line to create a boundary between core and cavity using 3D model.
  
                                     
  
  Figure 4

Tooling Split:

• Select Tooling Split to divide the part into Core and Cavity solid bodies.
• Streamlines mold design by automating complex geometry division.
• Ensures the mold opens and closes correctly.
• Prepares your design for toolpath generation or CAM operations.

Figure 5

Save Bodies:

• When modeling in-context multibody parts and you want to break them into separate components.
• For top-down assembly modeling, where you design all parts in one file and split them later.
• Export the core and cavity blocks as separate parts for machining.
• Organize your mold design into a clear, modular structure.
• Use each mold half in a larger mold base assembly.
  
  
  
  

  Figure 6

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