INDUSTRY COMPONENT

Plunger

A plunger is a precision cylindrical component in injection systems that creates pressure to force molten material into molds.

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Component Specifications

Definition
The plunger is a critical component in injection molding and die-casting systems, typically a cylindrical rod that moves within a barrel or cylinder. It functions as a piston to generate hydraulic or mechanical pressure that pushes molten plastic, rubber, or metal through a nozzle into a mold cavity. Plungers are engineered for precise displacement control, pressure maintenance, and material flow regulation during injection cycles.
Working Principle
The plunger operates on hydraulic or mechanical pressure principles. During the injection phase, it moves forward within the barrel, compressing the molten material ahead of it. This creates high pressure that forces the material through the injection nozzle into the mold. The plunger's reciprocating motion is precisely controlled to manage injection speed, pressure profiles, and material dosage.
Materials
Typically made from hardened tool steels (H13, D2), stainless steels (420, 440C), or tungsten carbide for wear resistance. Surface treatments include nitriding, chrome plating, or PVD coatings to enhance durability and reduce friction.
Technical Parameters
  • Diameter 20-150 mm
  • Stroke Length 100-800 mm
  • Surface Finish Ra 0.2-0.8 μm
  • Surface Hardness HRC 55-62
  • Operating Pressure 100-200 MPa
  • Straightness Tolerance 0.01-0.05 mm/m
Standards
ISO 10791-7, DIN 16760, ISO 12165

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Plunger.

injection plunger molding plunger hydraulic plunger plunger component injection system parts plunger specifications industrial plunger Plunger Plunger in Rubber and Plastic Product Manufacturing

Parent Products

This component is used in the following industrial products

Injection System

Component responsible for injecting molten metal into the die cavity under high pressure

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Dispensing Syringe/Barrel

The cylindrical container and delivery mechanism that holds and dispenses thermal paste in precise amounts.

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A precisely arranged set of spring-loaded electrical probes used to establish temporary electrical connections with test points on electronic devices or printed circuit boards (PCBs) during automated testing.

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Engineering Analysis

Risks & Mitigation
  • Wear and scoring from abrasive materials
  • Seal failure leading to pressure loss
  • Misalignment causing binding or uneven wear
  • Thermal expansion affecting dimensional accuracy
FMEA Triads
Trigger: Abrasive material particles
Failure: Surface scoring and increased clearance
Mitigation: Use hardened materials with protective coatings, implement filtration systems
Trigger: Improper alignment during installation
Failure: Uneven wear and binding
Mitigation: Follow precise installation procedures, use alignment tools, regular inspection
Trigger: Inadequate lubrication
Failure: Increased friction and overheating
Mitigation: Implement automated lubrication systems, use high-temperature lubricants

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
±0.01 mm for diameter, ±0.02 mm for straightness
Test Method
Dimensional verification with CMM, surface roughness testing with profilometer, hardness testing with Rockwell scale

Procurement Evaluation Criteria

Not customer reviews or live demand data. These dimensions support RFQ preparation and supplier evaluation.

Technical documentation
4/5
Manufacturing capability
4/5
Inspection readiness
5/5
Supplier transparency
3/5

These scores are example evaluation dimensions, not real customer ratings, country-specific buyer feedback, or live inquiry activity.

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Frequently Asked Questions

What is the main function of a plunger in injection systems?

The plunger creates pressure to force molten material into molds during injection cycles, controlling material flow and dosage.

How often should plungers be inspected and maintained?

Plungers should be inspected every 500-1000 operating hours for wear, scoring, or surface damage, with preventive maintenance including cleaning and lubrication.

What materials are best for plungers in high-wear applications?

Hardened tool steels with surface treatments like nitriding or tungsten carbide coatings provide optimal wear resistance for demanding applications.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

Data Basis

CNFX manufacturer profiles, technical classification, publicly available product information, and ongoing plausibility checks.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

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