Ningbo Fenghua Bolong Machinery Manufacturing Co., Ltd. is one of the leading manufacturers and suppliers of outer hub in China. Please feel free to buy durable outer hub made in China here from our factory. All customized products are with high quality and competitive price.
Core Advantages
Multi-Stage Cold Extrusion Process
The outer hub is formed through a carefully sequenced process involving pre-forming, intermediate lubrication, multiple extrusion stages, and finish machining. This progressive approach ensures consistent material flow, maximizes grain refinement, and achieves near-net shape dimensions that minimize subsequent machining.
01
Case-Hardened Spline Teeth
Following cold extrusion and machining, components undergo carburizing heat treatment to develop a hardened surface layer on internal spline teeth while maintaining a tough, fracture-resistant core. This hardness gradient ensures spline wear resistance under repeated engagement cycles and impact resistance under torque reversal loads.
02
Precision Machined Critical Features
CNC turning, drilling, and finishing operations are performed after cold extrusion and heat treatment, ensuring accurate bore diameters, mounting face flatness, and spline alignment. Component geometry is verified on CMM equipment to meet customer drawing specifications.
03
SAE 8620 / CL-18 Alloy Steel Construction
Both material grades are carburizing-grade low-carbon alloy steels widely specified for automotive driveline components requiring case-hardened surfaces, recognized for their excellent hardenability and fatigue resistance in gear and spline applications.
04
Complete Post-Processing Traceability
Each production lot undergoes full dimensional verification, hardness testing, and metallurgical inspection. Parts are marked with lot traceability codes, cleaned, and rust-preventative oiled before packaging. Inspection documentation includes material certificates, dimensional reports, and hardness test records.
05
Technical Specifications
|
Parameter |
Details |
|
Product Name |
Clutch Outer Hubs - Cold Extruded Outer Components |
|
Materials |
SAE 8620 (Ni-Cr-Mo alloy steel), CL-18 (case-hardening steel) |
|
Manufacturing Process |
Forging, normalizing, shot blasting, cold extrusion, CNC machining, carburizing, cleaning, rust prevention |
|
Internal Spline Features |
Cold extruded; case-hardened |
|
Case Hardness |
58-62 HRC (carburized layer) |
|
Core Hardness |
30-40 HRC |
|
Quality Systems |
IATF 16949 certified manufacturing; PPAP Level 3 available |
Manufacturing Process
|
Stage |
Key Operations |
|
Pre-Forming |
Forging → Normalizing → Shot blasting |
|
Cold Extrusion |
Multi-stage cold extrusion (with intermediate lubrication and cleaning) |
|
Machining |
CNC turning, drilling, deburring |
|
Heat Treatment |
Carburizing |
|
Final Operations |
Marking → Cleaning → Rust prevention → Packaging |
Quality Control
Pre-Forming Phase
Forged blanks are inspected for grain flow and normalized hardness. Shot blasting ensures surface cleanliness.
Cold Extrusion Phase
Each extrusion stage is monitored for dimensional consistency and surface quality. Intermediate cleaning and lubrication ensure consistent material flow across multiple extrusion stages.
Heat Treatment Phase
Carburizing case depth is verified, surface hardness (58–62 HRC) and core hardness (30–40 HRC) are tested per batch, and microstructure is inspected to confirm proper case and core transformation.
Final Release
Dimensional verification on CMM equipment confirms all critical features. Hardness test records and material certificates accompany each shipment. Full traceability links each finished part to its raw material heat lot and production batch.
Application Scenarios
Commercial Vehicle Clutch Assemblies
Outer hubs are essential components in diaphragm spring clutch systems for heavy-duty trucks, buses, and vocational vehicles. The cold-extruded internal spline engages with the transmission input shaft, while the outer housing retains the friction disc pack and damper spring assembly.
Automated Manual Transmission Systems
Hubs for AMT-equipped commercial vehicles require high torsional fatigue strength to withstand the frequent load reversals and automated shift cycles.
Passenger Car & Light Truck Applications
Outer hubs in passenger car clutches benefit from the weight reduction and dimensional consistency achieved through multi-stage cold extrusion.
Custom Services
Engineering consultation
Process recommendations based on your torque requirements, spline specifications, and commercial vehicle application
Custom cold extrusion
Hub geometry, spline profiles, and mounting features per your drawing
Material selection
SAE 8620, CL-18, or customer-specified grades
Heat treatment
Carburizing depth and hardness profiles per your specification
Sample support
Prototype quantities for validation and durability testing
Production volume
From pilot runs to high-volume production with full PPAP documentation
Whether you require cold extruded outer hubs for commercial vehicle clutch assemblies, case-hardened hubs for AMT applications, or precision outer components for heavy-duty drivelines - our engineering team provides full support from multi-stage extrusion design through heat treatment and production delivery.
Contact Us for Your New Project
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