Core Pins & Ejector Sleeves
straight, angled, custom profiles.
Huicheng manufactures core pins (顶针), ejector pins, ejector sleeves (司筒), ejector blades and custom ejection components to controlled drawings. Precision grinding, heat treatment and ID/OD grinding capability support standard sizes, custom profiles, angled pins and hardened guide sleeves.
Pins eject the part.
Sleeves guide and protect.
Ejector pins push molded plastic parts out of the cavity after the mold opens. Core pins form small internal features like holes, ribs and slots. Ejector sleeves guide pin movement, prevent deflection and protect the mold base from wear.
Pin and sleeve manufacturing requires precision cylindrical grinding for diameter control, heat treatment for hardness and wear resistance, and careful finish control on contact surfaces. Straight pins, angled pins, flat ejector blades and custom-profile pins all follow slightly different manufacturing routes depending on geometry, hardness requirement and volume.
Standard pins, sleeves
and custom profiles.
These photographs show representative pin and sleeve components from Huicheng’s factory. Customer names, drawing numbers and dimensional values are not shown.
Representative work only. Customer drawings, names, dimensions and project identifiers are not shown.
Control diameter, straightness
and surface finish.
Ejector pins and sleeves are precision cylindrical components. The manufacturing route must coordinate diameter tolerance, straightness, heat treatment and finish to ensure smooth ejection, minimal wear and long service life.
Drawing review and material selection
Confirm pin or sleeve type, standard size or custom, diameter tolerance, straightness requirement, hardness, surface finish and quantity. For angled pins or custom profiles, confirm angle accuracy and feature location.
Material and blank preparation
Select steel by wear resistance, toughness and heat treatment response. Standard materials include SKD61, SKH51 (high-speed steel), SUJ2 (bearing steel) and 304 stainless for corrosion resistance. Blanks are cut to length with grinding allowance.
CNC turning or milling for custom profiles
For custom pins with non-round features, heads, flats, slots or complex ends, CNC turning or milling precedes grinding. Standard round pins skip this step and go directly to grinding after heat treatment.
Heat treatment
Vacuum heat treatment to specified hardness (typically HRC 52–60 for ejector pins, HRC 58–62 for sleeves). Heat-treated pins are slightly oversized and may have minor distortion; grinding corrects both.
Precision cylindrical grinding
Control final diameter, straightness, concentricity and surface finish. ID/OD grinding for sleeves ensures inner bore and outer diameter are concentric. Angled pins require compound-angle grinding setup.
Final inspection
Measure diameter with micrometers or pin gauges, check straightness with a surface plate and dial indicator, verify hardness with Rockwell tester. Sleeves also require ID/OD concentricity and bore finish checks.
Match the steel to
wear, impact and corrosion.
Pin and sleeve material must balance wear resistance, toughness (to resist breakage) and dimensional stability after heat treatment. These are the most common steels:
General-purpose ejector pins
Good toughness and wear resistance at HRC 52–56. Suitable for most ejector pins and core pins in non-abrasive plastics. Standard choice for connector, electronics and automotive applications.
High wear resistance
High-speed steel with excellent wear resistance at HRC 60–62. Used for ejector pins in abrasive plastics (glass-filled, mineral-filled) and high-cycle production where standard tool steel wears too quickly.
Bearing steel for guide sleeves
Bearing-grade steel with high hardness (HRC 58–62), excellent wear resistance and good dimensional stability. Common choice for ejector sleeves and guide bushings where smooth, wear-resistant ID surface is critical.
Corrosion-resistant pins
For PVC, medical, food-contact and other corrosive plastic applications. Lower hardness (HRC 40–45) than tool steel; not suitable for high-wear applications but necessary when corrosion is a risk.
Extreme wear, long life
Powder metallurgy high-speed steel with superior wear resistance and toughness at HRC 62–64. Used for critical ejector pins in ultra-high-cycle molds, abrasive plastics or applications where pin breakage history exists.
What buyers usually
need to confirm.
What information is needed to quote ejector pins or sleeves?
Provide controlled drawings with diameter, length, tolerance, straightness requirement, material, hardness, surface finish, quantity and required delivery date. For angled pins, state the angle and whether angle tolerance must be controlled. For custom profiles, provide 2D and 3D geometry.
Can Huicheng manufacture angled ejector pins?
Yes. Angled pins up to approximately 30° from centerline can be ground. Confirm angle tolerance requirement, whether the angle must be inspected, and the method of measurement (sine bar, CMM, angle gauge).
What is the tightest diameter tolerance Huicheng can hold on pins?
Cylindrical grinding records show stable OD tolerance of 0.005 mm for ejector pins and sleeves. Tighter capability (0.002–0.003 mm) may be achievable depending on diameter, length, material and volume; confirm at RFQ.
Can pins and sleeves be supplied with coating or surface treatment?
Yes. Nitriding, PVD coating (TiN, TiAlN), chrome plating and DLC coating can be coordinated as external processes. State the required coating type, thickness and whether coating hardness or friction coefficient must be verified.
What is the maximum length for ejector pins?
Factory grinding capability supports pins up to 500 mm length. Long, slender pins require straightness control and deflection consideration; confirm straightness tolerance and measurement method at RFQ.
Can Huicheng supply standard HASCO, DME or MISUMI size pins?
Huicheng manufactures to customer drawings and specifications, not pre-stocked standard catalogs. If you require HASCO, DME or MISUMI equivalent sizes, provide the drawing or specification and Huicheng will quote to that geometry and tolerance.
Ready to quote pins or sleeves?
Send the drawing, material, hardness, diameter and straightness tolerance, quantity and target delivery date.