Ningbo Fenghua Bolong Machinery Manufacturing Co., Ltd. is one of the leading manufacturers and suppliers of inner hub in China. Please feel free to buy durable inner hub made in China here from our factory. All customized products are with high quality and competitive price.
Core Advantages
High-Strength Alloy Steel Construction - Manufactured from premium materials including SAE 8820 (nickel-chromium-molybdenum carburizing steel), CL18 (low-carbon case-hardening steel), and 15CrMo per GB/T 3077 (chromium-molybdenum heat-resistant steel). These alloys are selected for their excellent hardenability, fatigue resistance, and core toughness - providing the strength required to withstand torque loads up to 3,200Nm in heavy-duty clutch applications.
Case-Hardened Spline Teeth - The carburizing and quenching process produces a surface hardness of 58-62 HRC on the spline teeth while maintaining a tough core (30-40 HRC). This hardness gradient ensures wear-resistant spline engagement with the transmission shaft while preventing fracture under impact loads - critical for the frequent start-stop and torque reversal cycles common in commercial vehicle operation.
Precision Spline Machining - Internal and external involute splines are CNC-machined after heat treatment to tight tolerances, ensuring accurate engagement with transmission shafts and driven disc assemblies. Spline accuracy is verified on CMM equipment with complete dimensional reporting.
Optimized Forging Grain Flow - The closed-die forging process aligns the metal grain structure with the hub contour - following spline roots, flanges, and shoulder radii. This uninterrupted grain flow delivers superior fatigue resistance under cyclic torsional loading compared to machined-from-bar alternatives.
High-Temperature Material Option - The 15CrMo grade offers enhanced performance at elevated operating temperatures (up to 550°C), with oxidation resistance and sustained strength that contribute to extended service life in demanding powertrain environments.
Engineered for Eaton-Compatible Commercial Vehicle Clutches - Our hub designs are compatible with industry-standard clutch configurations for commercial vehicles - including 430mm diaphragm spring clutches and automated manual transmission (AMT) applications. Typical torque capacities range from 1,750 ft-lb to 2,050 ft-lb in heavy-duty drivelines, with support for both on-highway and vocational applications.
Complete Dimensional & Metallurgical Validation - 100% material certification with full chemical composition reporting. Spline geometry, bore diameter, and flange faces verified on CMM equipment. Hardness testing performed on each production batch per customer specifications. Full PPAP Level 3 documentation available for automotive and commercial vehicle applications.
Technical Specifications
|
Parameter |
Details |
|
Product Name |
Clutch Inner Hubs - Forged & Hardened Hub Components |
|
Materials |
SAE 8820, CL18, 15CrMo per GB/T 3077 |
|
Material Standards |
SAE/AISI, GB/T 3077 |
|
Manufacturing Process |
Closed-die forging → case carburizing → quenching/tempering → CNC spline machining |
|
Spline Configuration |
Internal involute spline; external spline or flange (per drawing) |
|
Spline Standard |
DIN/ANSI involute standards |
|
Case Hardness |
58-62 HRC (carburized layer) |
|
Core Hardness |
30-40 HRC |
|
Heat Treatment |
Carburizing, oil quenching, low-temperature tempering |
|
Size Range |
Spline diameters per customer requirements |
|
Quality Systems |
IATF 16949 certified manufacturing; PPAP Level 3 available |
Manufacturing Process
|
Stage |
Key Operations |
Quality Gates |
|
Material Prep |
Bar cutting → forging billet preparation |
Material certificate verification; chemical composition analysis |
|
Forging |
Closed-die precision forging → flash trimming → normalization |
Grain flow inspection; dimensional check |
|
Heat Treatment |
Case carburizing → oil quenching → low-temperature tempering |
Hardness (surface/core); case depth measurement; microstructure inspection |
|
CNC Machining |
Spline broaching/hobbing → internal bore finishing → face turning |
CMM verification; spline profile measurement; surface finish check |
|
Final Inspection |
100% spline gauge check → dimensional verification → hardness sampling |
Full dimensional report; hardness certification; traceability to heat lot |
Quality Control
Material Phase
Mill certificates verify material grade, chemical composition, and mechanical properties. 15CrMo material per GB/T 3077 includes verification of Cr (0.80-1.10%) and Mo (0.40-0.55%) content ensuring compliance with standard requirements.
Forging Phase
Forging temperature and reduction ratios are controlled to ensure uniform grain refinement. Grain flow inspection is performed on sample basis to verify correct material orientation through the spline root and hub sections.
Heat Treatment Phase
Case depth is measured on test specimens by micro-hardness traverse. Surface hardness (58-62 HRC) and core hardness (30-40 HRC) are verified on each production batch. Microstructure inspection confirms proper carburized case structure and core transformation.
Final Release
Spline geometry is verified using spline gauges and CMM equipment. All critical dimensions - bore diameter, flange faces, and spline alignment - are measured and documented. Full dimensional inspection reports and material certificates accompany each shipment with batch traceability.
Application Scenarios
Commercial Vehicle Clutch Driven Disc Assemblies
Inner hubs serve as the central hub of clutch driven discs in diaphragm spring clutch configurations for heavy-duty trucks, buses, and vocational vehicles. Typical clutch diameters include 430mm for standard heavy-duty applications, with damper sizes ranging from 158mm to 285mm depending on the torsional vibration requirements.
Automated Manual Transmission Applications
Hubs for Eaton UltraShift and other AMT systems require precise spline tolerances and high torsional fatigue strength. Case-hardened hubs are essential for the automated shift cycles of AMT-equipped commercial vehicles, which subject the hub to frequent load reversals and rapid engagement events.
Heavy-Duty On-Highway & Vocational Service
Standard Duty hubs for linehaul and regional delivery; Severe and Extreme Duty configurations for construction, waste management, and other demanding vocational applications requiring ceramic friction materials and higher thermal capacity alloys.
Custom Services
Engineering consultation
Application-specific material and heat treatment recommendations based on torque, duty cycle, and environmental requirements
Custom forging
Hub geometries and spline configurations per customer drawing
Material selection
SAE 8820, CL18, or 15CrMo per GB/T 3077 based on application requirements
Heat treatment
Customized carburizing depth and hardness profiles per specification
Sample support
Prototype quantities for validation testing and durability trials
Production volume
From pilot runs to high-volume production with full PPAP documentation
Whether you require splined clutch hubs for commercial vehicle drivelines, case-hardened hubs for AMT applications, or high-strength hubs for heavy-duty clutch assemblies - our engineering team provides full support from material selection through forging, heat treatment, and precision machining to production delivery.
Contact Us for Your New Project
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