High-Speed Steel Ejector Pin Assembly

Stable Part Release Under Repeated Mold Cycles

The high-speed steel ejector pin transfers controlled force from the mold ejection system to the finished component. Its ground cylindrical surface moves through the ejector plate and guide bore with limited clearance, helping plastic or stamped parts separate from the forming surface without sudden tilting, drag marks or concentrated pressure.

High-speed steel combines elevated hardness with the toughness needed for repeated impact and sliding contact. Quenching and tempering bring the material to HRC58–62, creating a wear-resistant working surface while retaining enough structural strength to withstand frequent mold cycles. This material remains stable in heated tooling where ordinary carbon steel may lose hardness or develop premature wear.

Precision Grinding for Smooth Ejection Motion

After heat treatment, cylindrical grinding controls the shank diameter, roundness, straightness and surface condition. Key dimensional tolerance can reach ±0.002 mm under confirmed drawing and inspection requirements. A consistent shank profile reduces binding inside the guide bore and limits side loading on the pin during forward and return movement.

The contact end can follow flat, stepped, contoured or non-standard shapes according to the molded part. A polished tip helps distribute ejection force over delicate surfaces, reducing white marks, dents and local deformation on clear, thin-wall or appearance-sensitive components. Head diameter, shoulder thickness and overall length can also match the ejector plate layout.

Optional nitriding, mirror polishing or wear-resistant coatings can address demanding cycle counts, filled resins and elevated mold temperatures. Each treatment is selected around the base hardness, sliding conditions and required surface finish rather than applied as a standard decorative layer.

Technological Process

1. Drawing & Process Design: Determine ejector pin specifications, tolerances and surface treatment solutions based on customer requirements, and optimize processing technology.
2. Material Cutting & Rough Machining: Cut high-speed steel bars to size and perform rough turning to remove most of the excess material.
3. Heat Treatment: Conduct quenching and tempering to stabilize material hardness at HRC58-62, improving wear resistance and toughness.
4. Precision Grinding: Precision grind the ejector pin shank on a cylindrical grinder to ensure dimensional accuracy and roundness; machine the head as required.
5. Surface Treatment (Optional): Conduct mirror polishing, nitriding or coating treatment as required to improve surface finish and wear resistance.
6. Inspection & Packaging: Fully inspect the ejector pins for dimensions, roundness, hardness and surface quality, then classify and package qualified products by specifications.

Core Advantages & Applications

Common Applications

• Injection Molds: Ejector pins for precision plastic parts, clear parts and thin-wall parts
• Stamping Dies: Ejection and positioning of metal parts, terminals and small stamped parts
• Automation Equipment: Locating pins, guide posts and ejection mechanism components
• Precision Fixtures: Positioning assemblies, support posts and ejection mechanism accessories

Before classification and packing, the finished high-speed steel ejector pin undergoes checks for diameter, straightness, roundness, hardness and visible surface defects. Monthly production capacity can reach 100,000 pieces under confirmed specifications, supporting matched sets, replacement quantities and recurring mold-component orders.

Specification Table