Injection molding design construction slide core

Slide core injection molding solve undercut in the products. This post will explain construction and design of it. How does slide core work?

I. Construction of slide core system.

Two pictures below will explain construction of slide core system.

1. Product.

2. Cavity plate.

3. Slide locking block: It uses to assemble an angular pin and cavity plate. It will increase strength for the angular pin when mold closed.
4. Angular pin: This pin has draft angle from 10 deg ~25 deg. It will transfer vertical movement of cavity plate to horizontal movement of slide core. Angular pin usually fixes by cavity plate and slide locking block.
5. Slide core: Slide core usually assembles in core plate. It will create shape of undercut.
6. Core plate

7. Spring: when angular pin and slide core separate, spring force will push slide core move forward.
8. Slide lock plate(slide core guide): This part will fix slide core move following horizontal. Slide locking block and slide core always have friction. It is easy for changing if slide has broken.
9. Core stop block: This part will stop movement of slide core when mold opening.

II. How does slide core of injection molding work?

1. When mold opening, because angular core pin attach in cavity so it is fixed.

2. Angular pin move following the core plate. Because slide lock plate, slide core will move following horizontal under force of angular pin.

3. When angular pin and slide core separate, spring will push slide core move  continuously.

4. When mold closing, angular pin will touch in the hole of slide core. Slide will move back and mold closing.

III. How to design slide core.

A: Undercut amount
B: Slide stroke amount

α: Tilt angle of slide core

β: Tilt angle of angular pin
B = A + 5 mm up
α = β+(2- 5)
β <= 20 ᵒ deg.

Gap between an angular pin and hole of slide core: ~0.5 mm.