Stepped Center Pins
Precision stepped center pins designed to support hollow ejector sleeves. Guarantees core stiffness and facilitates dual-diameter boss molding.
Product Categories
Selection Matrix: One-Step vs. Two-Step Pins
Determine the correct stepped center pin structure based on your core complexity and guide depth:
| Feature | One-Step Center Pins | Two-Step Center Pins |
|---|---|---|
| Diameter Transitions | One diameter change (guide base to molding tip) | Two diameter changes (guide base, secondary guide, tip) |
| Bending Rigidity | Standard guide base support | Maximum (reinforced double shoulder base) |
| Application Suitability | General deep bosses, single-stage ejection molds | Complex secondary demolding, high-precision electronics |
Decision rule: Use one-step pins for standard boss ejection. Only upgrade to two-step when your part geometry requires secondary ejection staging. For a deeper dive into two-step ejection mechanics, see our Secondary Ejection with Two-Step Center Pins guide.
Core cooling water loop design guidelines
Optimal design criteria for core center pins fitted with internal water cooling holes:
Cooling Hole Flow Rate Calculation
To maintain core temperatures below 80°C in heavy injection boss regions, center pins with internal cooling holes must support a flow rate of 3 to 5 L/min. This creates turbulent water flow (Reynolds number Re ≥ 4000) which optimizes heat transfer.
Water Circuit Inlet/Outlet Pressures
The cooling water loop pressure must be carefully controlled to prevent O-ring seal blowouts in the core backing plates while maintaining adequate circulation velocity. Consult your mold design manual for system-specific pressure ranges.
Frequently Asked Questions
What is the difference between one-step and two-step stepped center pins?+
What coolant flow rate is required for stepped center pins with cooling holes?+
How do stepped center pins improve molding accuracy of deep bosses?+
About Stepped Center Pins
Stepped center pins feature one or two diameter transitions along the shaft, providing increased rigidity and the ability to serve as internal cooling channels in deep-cavity molds. Available in one-step and two-step configurations, they are designed for applications requiring high core stability, multi-stage ejection, or integrated water cooling. All stepped center pins are precision-ground to tight runout tolerances for flash-free molding.
Engineering Resources
Need a Custom Quote?
Specify step diameters, length, and cooling hole requirements. Internal cooling channels available for deep-boss applications. Custom flow-rate calculations provided on request.