20# Steel Precision Honed tube is a high-quality cold drawn seamless steel tube that undergoes a specialized finishing process known as honing. The "20#" designation refers to a Chinese standard (GB/T 699) for high-quality carbon structural steel, which is approximately equivalent to ASTM A513 Type 5 or SAE 1020 steel. This combination of material and precision manufacturing results in a product renowned for its excellent mechanical properties, tight dimensional accuracy, and superior internal surface finish.

Material Properties: 20# Steel

20# steel is a popular choice for honed tubes due to its balanced composition:

Good Strength and Toughness: It offers an optimal blend of strength and ductility, making it suitable for high-pressure applications.

Excellent Machinability: Its carbon content (around 0.17-0.24%) allows for easy cutting, welding, and further processing.

Uniform Microstructure: Provides consistent hardness and performance throughout the tube length.

Manufacturing Process

The production of 20# Honed Tubes involves two critical stages:

Cold Drawing (CDS): A seamless steel shell is drawn through a die at room temperature. This process increases the tube's dimensional accuracy, mechanical strength, and surface smoothness.

Honing: The cold drawn tube is then subjected to the honing process. Abrasive stones are passed through the bore under controlled pressure and motion. This precision operation achieves three key outcomes:

Ultra-Smooth Inner Surface (ID): Achieves a very low surface roughness (typically Ra ≤ 0.4 µm or better).

Precise Dimensional Tolerance: Provides extremely tight inner diameter (ID) tolerances.

Improved Geometric Characteristics: Ensures exceptional straightness and roundness.

Key Features & Advantages

Superior Surface Finish: The mirror-like finish minimizes friction and wear on seals and pistons, extending the service life of the entire hydraulic or pneumatic system.

High Dimensional Accuracy: Guarantees perfect fit and smooth operation with other components like pistons and glands.

Excellent Straightness and Roundness: Critical for preventing premature seal failure and ensuring efficient, leak-free operation.

No Material Fatigue: The honing process removes surface stress micro-cracks, enhancing the tube's fatigue resistance.

Ready-to-Use: The ID surface requires no additional machining or polishing after honing, saving time and cost in assembly.

Typical Applications

20# honed tubes are the preferred component in systems requiring reliable and efficient linear motion:

hydraulic cylinders: As the main barrel for single-acting and double-acting cylinders.

Pneumatic Cylinders: For high-precision air cylinders.

Automotive Shock Absorbers: As the pressure tube.

Precision Machinery: As guide sleeves, bearing housings, and linear motion shafts.

Plastic Injection Molding Machines.

Packaging and Quality Assurance

These tubes are typically supplied with plastic end caps to protect the精密 honed inner surface from damage, moisture, and contaminants during transport and storage. Quality is ensured through strict compliance with international standards such as DIN 2391, ASTM A513, and GB/T 3639.