Product Overview

Heat treatment of Hollow Steel Shaft

Quenching and QPQ nitriding are the key steps to improving their overall performance:

Quenching: Rapid cooling increases the surface hardness, wear resistance being the primary benefit observed.

QPQ nitriding - the specific process - forms some sort of hard nitriding layer on the surface; further improving (to a small degree) both wear and corrosion resistance.

Key Features and Advantages

• Exceptional Wear Resistance: The QPQ process creates an extremely hard, nitride layer on the surface of the hollow steel rod. This hardness minimizes wear and scoring from the rod seal inside the cylinder, which is the primary cause of gas spring failure. This leads to a longer operational lifespan, often exceeding 100,000 cycles.

• Superior Corrosion Resistance: The post-oxidation step in the QPQ process generates a dense magnetite (Fe₃O₄) layer on top of the nitride layer. This offers excellent resistance to rust and corrosion from humidity, sweat, and occasional spills, which is crucial for furniture in homes and offices.

• Low Friction Coefficient: The surface is very smooth and has self-lubricating properties. This ensures smooth, quiet, and consistent movement (extension/compression) of the gas spring without stick-slip effect.

• Good Ductility of the Core Material: While the surface is extremely hard, the core of the hollow steel rod remains tough and ductile. This "hard surface, tough core" combination provides excellent resistance to impact and bending, preventing permanent deformation under load.

• Excellent Anti-fretting Properties: Resists micro-wear that can occur from tiny vibrations between the hollow steel shaft and the seal, which is a common issue in dynamic applications.

Application of hollow steel rod and the more recent QPQ technology within the furniture industry:

1) Office chair lifting mechanisms - stable support and near perfect smooth movement are provided by the hollow steel shaft, long term durability from the QPQ is a constant requirement.

2) Bed adjustment mechanisms, height (head/foot) adjustments being the prime example, again smoothness and reliability of use are the end goals, QPQ treated rods fulfilling this need.

3) Lifting doors and smaller drawer systems, cushioning support is what is required, all aspects of daily use corrosion and/or physical stress will always push the hollow steel rod to be at least partially QPQ treated. hollow steel shafts are and will remain a near universal solution to many types of mechanical support in furniture making.

Benefits of Using Hollow Steel Shafts Over Solid Steel Shafts

1. Weight Reduction

Hollow shafts can achieve the same or better performance while being up to 40-60% lighter than solid.

2. Improved Torsional Stiffness

The material distributed further from the neutral axis increases the polar moment of inertia, making them more resistant to twisting under torque.

3. Better Heat Dissipation

The hollow design allows for improved airflow and heat dissipation, which is particularly beneficial in high-speed rotating applications.