How Undercut Features Are Solved in Complex Injection Mold Designs

Injection molded products often require complex geometries—such as undercuts—that cannot be released from a mold in a straight pull. Without smart mold design, these features can delay production or increase defect rates.

At Dongxinda Mould Technology Co., Ltd., we solve undercut challenges through intelligent engineering, advanced machining, and robust side-action systems that allow our clients to mold high-function, high-precision parts efficiently.

What Are Undercuts?

Undercuts are recessed features that prevent a part from being ejected directly from the mold. Examples include holes, snap-fits, side slots, or external ribs perpendicular to the mold opening direction.

Our Engineering Solutions Include:

• Slides (Side Actions): Move laterally during mold opening to release undercuts.

• Lifters: Tilt to release undercuts on angled or curved surfaces.

• Collapsible Cores: Used in cylindrical or internal features without needing side movement.

• Unscrewing Mechanisms: For threaded parts like bottle caps and valves.

These systems are integrated with cooling, venting, and ejection designs to maintain efficiency and mold longevity.

Benefits of Proper Undercut Handling:

• Allows greater design freedom without part redesign

• Reduces risk of damage during ejection

• Maintains cosmetic and dimensional accuracy

• Enables automation even with complex features

FAQs:

• Are undercut molds more expensive?
  Slightly, due to additional components, but they prevent costly redesigns.

• Can Dongxinda assist with part design to avoid unnecessary undercuts?
  Yes, we offer full DFM analysis to help optimize part geometry.

• Do you manufacture molds with collapsible cores?
  Absolutely—we use them for medical and packaging components frequently.