Guide Bore: Diameter Tolerance ±0.005 mm

Component Specifications

Definition

A guide bore is a precisely machined cylindrical cavity within an ejector housing component of injection molding machines, designed to maintain strict alignment and smooth linear motion of ejector pins during the ejection phase of the molding cycle. It ensures consistent part release by preventing pin deflection, binding, or misalignment that could damage molded parts or the mold itself.

Working Principle

The guide bore operates on the principle of constrained linear motion, providing a hardened, low-friction surface that restricts ejector pin movement to a single axis. During ejection, hydraulic or mechanical force drives the ejector plate forward, pushing pins through these bores to contact and dislodge molded parts from the cavity. The bore's precise diameter and surface finish minimize clearance while allowing smooth sliding, ensuring pins return accurately to their retracted positions.

Materials

Typically made from hardened tool steels (e.g., AISI D2, H13, or S7) or carbide inserts for wear resistance. Surface treatments like nitriding, chrome plating, or TiN coating may be applied to reduce friction and extend service life. Hardness ranges from 48-62 HRC depending on application demands.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Depth	Varies by mold design (typically 50-200 mm)
Straightness	0.01 mm per 100 mm
Concentricity	Within 0.01 mm relative to mating features
Surface Finish	Ra 0.4 μm or better
Diameter Tolerance	±0.005 mm

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

Standards

ISO 286-2, DIN 7154

Engineering Analysis

Risks & Mitigation

Misalignment causing part defects
Wear leading to increased clearance and flash
Corrosion in humid environments
Thermal expansion mismatches

FMEA Triads

Trigger: Inadequate lubrication or contamination
Failure: Accelerated abrasive wear and scoring
Mitigation: Implement regular cleaning and use high-temperature, mold-safe lubricants; install protective seals

Trigger: Material fatigue from cyclic loading
Failure: Cracking or deformation of the bore
Mitigation: Use fatigue-resistant steels (e.g., H13), ensure proper heat treatment, and avoid over-tightening during assembly

Trigger: Improper installation or misalignment
Failure: Binding or uneven wear of pins and bores
Mitigation: Follow precise alignment procedures during mold assembly; use jigs and verify concentricity with dial indicators

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Meets ISO 286-2 for cylindrical fits (e.g., H7/g6 clearance fit)

Test Method

Dimensional verification with bore gauges or CMM; surface roughness testing per ISO 4287; hardness testing per ISO 6508

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

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Manufacturers of Guide Bore

Manufacturer profiles associated with Guide Bore.

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

What happens if a guide bore wears out prematurely?

Premature wear can cause ejector pin misalignment, leading to part damage, flashing, or mold scoring. It increases downtime for repairs and may require re-machining or replacement of the housing.

How often should guide bores be inspected?

Inspect during regular mold maintenance cycles (every 50,000-100,000 cycles for high-volume production). Check for scoring, diameter enlargement, or loss of surface finish using bore gauges and visual inspection.

Can worn guide bores be repaired?

Yes, through re-machining to a larger diameter and fitting with bushings or sleeves, though this may require matching ejector pin replacements. Severe damage often necessitates full housing replacement.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

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.

Guide Bore