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How leaf springs are made

Leaf springs are essential components of commercial vehicle suspension systems. They support heavy loads, absorb road shocks, and ensure vehicle stability. Understanding how leaf springs are manufactured helps explain their durability and performance. Below is a detailed overview of the modern leaf spring production process.

1. Raw Material Selection

Leaf springs are produced from high-strength spring steel with a controlled chemical composition. This steel provides:

  • High tensile strength
  • Excellent fatigue resistance
  • Elastic recovery after deformation

All incoming steel is inspected and tested to ensure it meets international quality standards.

2. Cutting and Profiling

Steel strips are cut to precise lengths based on engineering drawings. Each leaf is then shaped to specification.

For parabolic leaf springs, CNC-controlled machines form the variable thickness profile, reducing weight while maintaining strength.

3. Eye Forming

For eye-to-eye leaf springs:

  • Leaf ends are heated
  • Formed into rolled eyes
  • Bushings are installed if required

This process ensures secure mounting and long service life.

4. Heat Treatment Process

Heat treatment is critical to achieving correct spring properties.

Hardening

Leaves are heated to high temperatures and rapidly quenched in oil to increase hardness.

Tempering

After hardening, leaves are tempered to achieve:

  • Optimal flexibility
  • High toughness
  • Long fatigue life

5. Shot Peening

Shot peening strengthens the spring surface by:

  • Creating compressive stress layers
  • Reducing crack formation
  • Extending service life

6. Camber Setting

Each leaf is pressed into a precise camber shape to ensure correct ride height and load performance.

7. Assembly

For conventional multi-leaf springs:

  • Leaves are stacked
  • Center bolts are installed
  • Clamps are added for alignment

8. Surface Treatment and Corrosion Protection

To protect against corrosion, leaf springs receive:

  • Powder coating
  • Industrial paint
  • Phosphate or anti-corrosion layers

9. Quality Control and Testing

Each leaf spring is inspected and tested:

  • Dimensional accuracy
  • Load capacity testing
  • Fatigue testing (sample batches)
  • Visual inspection

Conclusion

Modern leaf spring manufacturing combines precision engineering, advanced metallurgy, and strict quality control. Each production stage ensures long service life, safety, and consistent performance.

At NovaSpring, we manufacture leaf springs according to OEM standards for trucks, trailers, and heavy-duty vehicles worldwide.