Product Description

420J2 Stainless Steel Long Shaft with Side Holes and Threads CNC Milled Component is a high-strength, precision-engineered mechanical part designed for demanding power transmission, actuation, or positioning systems. Manufactured from martensitic 420J2 stainless steel, this component offers excellent hardness and wear resistance after heat treatment. The defining features—a long shaft geometry, precisely located side holes (for lubrication, pinning, or sensing), and accurately machined threads (for mounting or adjustment)—are all produced through advanced multi-axis CNC milling. This integrated machining approach ensures strict concentricity, positional accuracy, and the durability required for high-load, high-cycle applications in industrial, automotive, and specialized machinery.

Product Processing

1. Material Selection & Stress Relieving: A 420J2 stainless steel round bar is selected and may undergo a preliminary stress relief to minimize distortion during subsequent machining and heat treatment.

2. Initial Turning & Center Preparation: The bar is turned on a CNC lathe to establish the primary shaft diameters and create precise center bores at each end. These centers are critical for supporting the shaft during the long, precise milling operations to follow.

3. Precision CNC Milling Setup: The shaft is mounted between live centers or in a steady rest on a multi-axis (4-axis or 5-axis) CNC milling machine. This setup provides the rigidity needed for accurate feature machining along the entire length.

4. Feature Machining (Core Process):

   • Side Hole Drilling & Milling: Using long-reach drills and end mills, precision side holes are machined. These can be simple through-holes, cross-holes, or complex multi-diameter ports. Their position along the shaft length is controlled with high accuracy.

   • Thread Milling: Threads are cut using thread milling cutters. This method is preferred for its accuracy, excellent thread finish, and ability to machine threads in difficult locations or materials. Both external and internal threads can be produced.

   • Keyway/Spline Milling (Optional): If required, longitudinal keyways or splines are milled along the shaft.

5. Heat Treatment (Hardening & Tempering): After all features are machined in the annealed (soft) state, the entire component undergoes vacuum hardening followed by multiple tempering cycles. This achieves the target high surface hardness (typically 50-55 HRC) for wear resistance while maintaining core toughness.

6. Post-Heat Treatment Finishing: Critical bearing or sealing diameters may be precision ground after heat treatment to correct any minimal distortion and achieve final ultra-tight tolerances and surface finish. Threads are chased if necessary.

7. Final Cleaning, Inspection & Marking: The shaft is cleaned, and often black oxide coated or passivated for corrosion protection. It undergoes 100% dimensional inspection (CMM for critical features) and hardness testing. Laser marking for part identification is applied.

Product Applications

• Industrial Hydraulic & Pneumatic Cylinders: As a piston rod with threaded ends for attachment and cross-holes for pinning or porting.

• Automotive & Heavy Machinery: Gearbox shafts, actuator shafts, or linkage rods requiring side holes for lubrication channels or retaining pins, and threads for mounting components.

• Printing & Packaging Machinery: Drive shafts or roller mandrels with threaded ends for bearing locknuts and side ports for internal cooling or vacuum channels.

• Textile & Food Processing Equipment: Stainless steel shafts for conveyors or rollers where corrosion resistance and cleanability are important, featuring threads for end caps and holes for mounting flights or blades.

• Valve & Pump Manufacturing: As a valve stem or pump shaft with threads for actuators and cross-holes for pressure equalization or sensing.

Product Technical Parameters (Detailed Table)