Editorial Technical Reference

Ejection System

This page explains how Ejection System is classified within Rubber and Plastic Product Manufacturing. Technical values and manufacturer relationships are research references; confirm the current specification and supplier evidence for each order.

Technical Definition & Core Assembly

A mechanism within injection molds that pushes finished plastic parts out of the mold cavity after cooling and solidification.

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Product Specifications

Technical details and manufacturing context for Ejection System

Definition
The ejection system is a critical component of injection mold assemblies responsible for safely and efficiently removing molded plastic products from the mold. It operates after the cooling cycle when the plastic has solidified, using mechanical force to separate the part from the mold surfaces without causing damage to the product or the mold itself. The system typically consists of ejector pins, plates, and return pins that are activated by the molding machine's hydraulic or mechanical ejection mechanism. When the mold opens, the ejection system advances forward, pushing the ejector pins against the molded part to dislodge it from the core or cavity. After ejection, the system retracts to its original position for the next molding cycle. The ejection stroke must exceed the part depth to ensure full ejection, typically ranging from 10 to 100 mm. Ejection force, usually between 5 and 50 kN, must be sufficient to overcome part sticking. Ejection speed is controlled between 0.1 and 0.5 m/s to avoid damaging delicate parts. The number of ejector pins, typically 4 to 20, is selected to reduce part deformation. Ejector pin diameters follow standard sizes (JIS B 5012) from 2 to 12 mm for interchangeability. Operating temperature ranges from -20 to 120°C; above 120°C, ejector pins may soften. Operating pressure is 1.0 to 1.6 MPa. Hydraulic cylinder bore, per ISO 6020-2, ranges from 32 to 100 mm for higher force. Return stroke speed is 0.2 to 0.8 m/s; too fast may cause impact damage. Positioning accuracy of ±0.05 mm ensures consistent ejection alignment. Ejector plate thickness, 15 to 40 mm, resists bending under load. The system weight is 5 to 50 kg, affecting handling and installation. Materials commonly used include tool steel, hardened steel, and stainless steel. These values are reference ranges; verify model-specific parameters with the manufacturer.
Working Principle
The ejection system operates after the cooling phase when the plastic part has solidified. The molding machine's hydraulic or mechanical mechanism activates the ejector plates, which advance forward. Ejector pins, attached to the plates, push against the molded part to dislodge it from the core or cavity. The return pins ensure proper retraction after ejection. The system's stroke, force, and speed are set to match the part geometry and material. After ejection, the system retracts to its original position, ready for the next molding cycle.
Common Materials
Tool steel, Hardened steel, Stainless steel
Technical Parameters
ParameterTypical rangeNotes & selection driver
Ejection Stroke10–100 mmMust exceed part depth for full ejection.
Ejection Force5–50 kNInsufficient force causes part sticking.
Ejection Speed0.1–0.5 m/sHigh speed may damage delicate parts.
Number of Ejector Pins4–20 pcsMore pins reduce part deformation.
Ejector Pin Diameter2–12 mmStandard sizes for interchangeability.JIS B 5012
Operating Temperature-20–120 °CAbove 120°C may soften ejector pins.
Hydraulic Cylinder Bore32–100 mmLarger bore for higher force.ISO 6020-2
Return Stroke Speed0.2–0.8 m/sToo fast may cause impact damage.
Positioning Accuracy±0.05 mmEnsures consistent ejection alignment.
Ejector Plate Thickness15–40 mmThicker plate resists bending under load.
Weight5–50 kgAffects handling and installation.

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM
  • Ejector Pin Part
    Directly contacts and pushes the molded part out of the mold
    Material: Hardened tool steel
  • Ejector Plate Part
    Holds and aligns ejector pins, transfers ejection force from the machine
    Material: Steel
  • Return Pin Part
    Ensures ejector system retracts properly after ejection
    Material: Steel
  • Ejector Housing
    Encloses and supports the ejection mechanism components
    Material: Steel

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Mold Assembly
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Case Forming and Drawing Press
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Precision Stamping Module
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Industrial Ecosystem & Supply Chain Structure

Complementary Systems
Downstream Applications
Specialized Tooling

Application Fit & Sizing Matrix

Operational Limits
pressure: Up to 200 bar (ejection force capacity)
other spec: Cycle time: 2-60 seconds, Stroke length: 5-300 mm, Actuation: Hydraulic/Pneumatic/Electric
temperature: Ambient to 150°C (mold operating temperature range)
Media Compatibility
✓ Thermoplastics (PP, ABS, PE) ✓ Thermosets (epoxy, phenolic) ✓ Elastomers (TPE, silicone)
Unsuitable: Abrasive-filled composites (e.g., glass fiber >40%)
Sizing Data Required
  • Part geometry and draft angle
  • Projected area and ejection force required
  • Mold plate thickness and available space

Reliability & Engineering Risk Analysis

Failure Mode & Root Cause
Hydraulic seal degradation
Cause: Contamination of hydraulic fluid with particulates leading to abrasive wear, or chemical incompatibility causing seal swelling/cracking
Pneumatic valve sticking/failure
Cause: Moisture accumulation in compressed air lines causing corrosion, or buildup of contaminants/oil residues on valve components
Maintenance Indicators
  • Inconsistent ejection timing or force (audible as irregular 'whoosh' or 'thud' sounds)
  • Visible hydraulic fluid leaks around cylinders or fittings, or excessive air exhaust mist
Engineering Tips
  • Implement strict fluid/air filtration maintenance: Use 10-micron filters for hydraulics and coalescing filters with automatic drains for pneumatics, with scheduled replacements
  • Establish predictive maintenance with vibration analysis on actuators and pressure transducers to monitor for early degradation before functional failure occurs

Indicative industry ranges for design and RFQ preparation. Confirm the exact figures and applicable standard with the manufacturer before specifying.

Compliance & Manufacturing Standards

Applicable Standards
ISO 12100:2010 - Safety of machinery ANSI B11.19-2019 - Performance criteria for safeguarding DIN 8580:2003-09 - Manufacturing processes

Quoted from the published standard.

Manufacturing Precision
  • Piston rod diameter: +/-0.01mm
  • Cylinder bore roundness: 0.005mm
Quality Inspection
  • Pressure decay leak test
  • Hardness verification test (Rockwell C scale)

Manufacturers of Ejection System

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Frequently Asked Questions

What is the function of an ejection system in injection molding?

It removes the solidified plastic part from the mold cavity after cooling, using ejector pins and plates to push the part out without damage.

What are typical ejection stroke and force values?

Ejection stroke typically ranges from 10 to 100 mm, and ejection force from 5 to 50 kN, but these must be confirmed for the specific application.

How does ejector pin diameter affect performance?

Pin diameter, typically 2 to 12 mm per JIS B 5012, influences part deformation and force distribution. More pins or larger diameters may be needed for delicate parts.

What materials are commonly used for ejection systems?

Tool steel, hardened steel, and stainless steel are typical materials, chosen for strength and wear resistance.
Data basis: editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

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