what is unscrewing mold

 An unscrewing mold is a special type of plastic injection mold designed for producing threaded plastic parts (like bottle caps, closures, or threaded connectors) that can’t be ejected simply by stripping or using lifters.

Because these parts have internal or external threads, they need to be rotated (unscrewed) before they can be removed from the mold without damage.

Key Points about Unscrewing Molds:

1. Purpose

   • Used when the product has precise threads that must remain intact (e.g., caps, medical connectors, threaded knobs, syringes).

2. Working Principle

   • Instead of ejector pins pushing the part out, the mold has a mechanical or hydraulic unscrewing mechanism.

   • After molding, the core (which forms the internal threads) rotates, unscrewing the part so it can be ejected safely.

3. Drive Mechanisms

   • Rack & pinion system: Mold opening motion drives gears to rotate the core.

   • Hydraulic motors: Directly rotate threaded cores.

   • Electric motors/servo systems: Allow precise control for high-volume, high-precision parts.

4. Advantages

   • Ensures threads are perfect and undamaged.

   • Allows mass production of threaded plastic parts.

   • Works for both internal and external threads.

5. Applications

   • Bottle caps, closures with tamper-proof features

   • Plastic syringes

   • Threaded automotive parts

   • Electrical and plumbing connectors

An unscrewing mold is a type of injection mold that uses a mechanical or motor-driven system to rotate and release threaded plastic parts during ejection.