Loose Cores (Lifters)
Loose cores and lifters for internal undercuts ejection.
Lifter Type Comparison
Loose cores (lifters) handle internal undercuts that slide cores cannot reach. Different actuation bases provide varying degrees of stability.
| Feature | T-Slot Sliding Base | Cylindrical Articulating Base | Spring-Loaded Lifters |
|---|---|---|---|
| Motion Path | Strictly linear along angle | Can accommodate slight flex | Linear |
| Load Capacity | High (supports heavy cores) | Medium | Low |
| Machining Complexity | High (requires precise T-slots) | Low (simple bored hole) | Low |
| Space Required | Large footprint in ejector plates | Small footprint | Very small |
| Best For | Large internal undercuts (automotive) | Standard consumer goods | Small snap hooks |
Lifter Kinematics & Mechanics
Stroke Calculation
Lifter horizontal release stroke (X) is determined by the ejector plate vertical stroke (Y) and the lifter angle (θ): X = Y × tan(θ). Lifter angles should ideally be kept between 5° and 10°. Exceeding 12° creates severe binding forces on the ejector plates and the lifter guide hole, requiring specialized oilless bushings to prevent seizure.
Guide Plate Necessity
Because the lifter rod is long and slender, injection pressure can easily deflect it, causing flash or dimensional inaccuracy. A hardened steel or bronze guide plate installed just below the cavity is mandatory to support the rod against lateral injection forces.
Application Scenarios
Internal Snap Fits
Consumer electronics enclosures requiring internal retaining clips that cannot be molded with bypass shut-offs.
Deep Draw Internal Undercuts
Requires long ejector strokes where lifter angles exceed 10°, creating high bending moments.
Technical Resources
Need a Custom Quote?
Send your specifications and receive a quote. MOQ: 1 piece. Custom dimensions available.