Shaft Body / Journal: Length Range 100-6000 mm

Component Specifications

Definition

The shaft body, also known as the journal, is the central cylindrical section of a ball screw shaft designed to interface with support bearings. This precision-ground component provides the rotational axis for the screw, maintains alignment under axial and radial loads, and ensures smooth motion transmission by minimizing deflection and vibration. Its dimensional accuracy and surface finish directly impact the ball screw's positioning precision, load capacity, and service life.

Working Principle

The shaft body rotates within precision bearings (typically angular contact or deep groove ball bearings) to convert rotary motion into linear motion via the ball nut. It maintains geometric stability under combined loads (axial, radial, and moment) while providing a low-friction surface for bearing contact. Proper preload and lubrication at the journal interfaces minimize wear and thermal expansion effects.

Materials

High-carbon chromium bearing steel (e.g., SUJ2, AISI 52100), case-hardened steels (e.g., SCr420, 8620), or stainless steels (e.g., SUS440C) with hardness typically 58-62 HRC. Surface treatments may include black oxide coating or phosphate coating for corrosion resistance.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Hardness	58-62 HRC
Roundness	≤ 0.005 mm
Length Range	100-6000 mm
Straightness	≤ 0.01 mm/m
Surface Roughness	Ra 0.4 μm or better
Diameter Tolerance	h5 or h6 (ISO)

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 3408, DIN 69051, JIS B 1192

Parent Products

This component is used in the following industrial products

Ball Screw Shaft

The precision-ground shaft that forms the core of a ball screw assembly, converting rotary motion into linear motion.

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Engineering Analysis

Risks & Mitigation

Brinelling from shock loads
Fretting corrosion at bearing interfaces
Thermal expansion causing binding
Surface degradation from improper lubrication

FMEA Triads

Trigger: Insufficient lubrication or contamination
Failure: Accelerated wear and scoring on journal surface
Mitigation: Implement automatic lubrication systems with filtration; use sealed bearing units

Trigger: Misalignment during installation
Failure: Premature bearing failure and shaft deflection
Mitigation: Use alignment fixtures and dial indicators during assembly; specify proper mounting tolerances

Trigger: Excessive preload or overload
Failure: Permanent deformation (Brinelling) of journal surface
Mitigation: Calculate and verify load ratings; install overload protection devices

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Geometric tolerances per ISO 1101:2017; diameter tolerances per ISO 286-1:2010

Test Method

CMM measurement per ISO 10360-2; surface roughness testing per ISO 4287; hardness testing per ISO 6508-1

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

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Inspection readiness

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Manufacturers of Shaft Body / Journal

Manufacturer profiles associated with Shaft Body / Journal.

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Frequently Asked Questions

What is the difference between shaft body and journal in ball screw terminology?

In ball screw context, 'shaft body' refers to the entire cylindrical section, while 'journal' specifically denotes the bearing contact surfaces. However, these terms are often used interchangeably for the load-bearing portion.

How does journal diameter tolerance affect ball screw performance?

Tighter diameter tolerances (e.g., h5 vs. h6) reduce bearing clearance, improving rigidity and positioning accuracy but requiring more precise mounting. Looser tolerances accommodate thermal expansion but may increase vibration.

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.

Shaft Body / Journal