Ejector Sleeves
Where a boss must be ejected around its core pin, only a sleeve can push evenly on the ring of plastic — the ejector sleeve is that part.
What are ejector sleeves?
An ejector sleeve is a hardened, thin-walled hollow ejector that slides over a stationary core pin. On ejection it pushes the moulded boss off the core evenly, avoiding the distortion a single pin would cause. Wall thickness, concentricity and finish are critical because the sleeve runs steel-on-steel over the core pin.
Typical materials
SKD61 nitrided is standard; the mating core pin is typically SKD61 or SKH51, sized to run inside the sleeve with a controlled clearance.
Types of ejector sleeves
Standard ejector sleeves (SKD61)
Nitrided hot-work steel — the common specification.
Thin-wall sleeves
For small bosses; require careful support and fitting.
Stepped sleeves
Reinforced body stepped to the working wall for stiffness.
How to select ejector sleeves
- Core pin diameter (sleeve bore) and boss outside diameter (sleeve OD).
- Overall length to reach through the ejector stroke.
- Wall thickness — thicker where possible for life.
- Matched core pin supplied together for correct running fit.
Not sure? Send what you have — a part number, drawing or photo — and our engineering team will confirm the selection.
Frequently asked questions
- Why use an ejector sleeve instead of pins beside the boss?
- Pins beside a boss push the surrounding face, often distorting or stressing the boss root. A sleeve pushes the boss itself, squarely around its full circumference, releasing it cleanly from the core pin.
- Should the core pin and sleeve be ordered together?
- Yes — they work as a matched pair with a controlled running clearance. Order both together (or send the existing pair's sizes) for correct fit.
Related components
Ejector Pins
Ejector pins push the finished part off the core when a plastic mould or die opens. They cycle millions of times against heat and friction, so material, hardness and fit decide tool life.
Core Pins
Core pins form the holes and bosses in a moulded part — precision pins that live inside the cavity, cycling with every shot.
Mould Cooling Components
Cooling decides cycle time. Baffles, plugs and nipples route water through the mould so every cavity region holds the right temperature.
Need ejector sleeves?
Tell us the specification, quantity and application — or just send the drawing.