Cold-drawn precision steel tubes are engineered to tight dimensional tolerances and superior surface finishes via precision cold drawing over mandrels or through sinking dies. By altering the microstructural grain alignment under cold work, these tubes deliver significantly enhanced yield strength and tensile strength compared to hot-rolled counterparts, eliminating extensive pre-machining.
Built for high-pressure, high-stress environments, they provide exact concentricity and smooth wall surfaces for hydraulic systems, automotive power trains, and high-performance mechanical assemblies.
Specifications
|
Parameter |
Technical Range |
|
Manufacturing Method |
Cold Drawn Seamless (CDS) / Drawn Over Mandrel (DOM) |
|
Outer Diameter (OD) |
10 mm - 219 mm (0.39 in - 8.62 in) |
|
Wall Thickness (t) |
1 mm - 20 mm (0.039 in - 0.787 in) |
|
Standard Lengths |
5.8 m, 6 m, or precision cut-to-length (±0.5 mm) |
|
Dimensional Tolerance |
OD/ID up to ±0.08 mm (Complying with ISO Class D4/H4 or EN 10305) |
|
Surface Condition |
Black (phosphated & oiled), Bright cold-drawn, or Roller-burnished/Honed ID |
Material & Manufacturing
Steel Grades & Standards
European Grades: E235 (+C/+N), E355 (+C/+N), C45E (Per DIN EN 10305)
North American Grades: AISI 1020, AISI 1045, AISI 4130 (Per ASTM A519)
Delivery Conditions (EN 10305-1):
+C (BK): Cold drawn / hard (un-annealed, high yield strength)
+LC (BKW): Cold drawn / soft (light cold work post-annealing)
+SR (BKS): Stress relieved (internal stresses removed for distortion-free machining)
+A (GBK): Annealed (softened microstructure for maximum formability)
+N (NBK): Normalized (controlled re-crystallization for homogeneous mechanical properties)
Production Process & Mill Capabilities
Mother tubes undergo acid pickling and zinc-phosphate coating followed by reactive soap lubrication. Drawing is performed on multi-bench hydraulic draw lines equipped with tungsten carbide dies. Subsequent thermal processing is executed in continuous, protective-atmosphere roller hearth furnaces to prevent decarburization and scale formation, ensuring uniform metallurgical structures.
Quality Inspection & Traceability
Strict verification protocols are embedded into every production batch to guarantee consistency and compliance:
Inline Non-Destructive Testing (NDT): 100% Eddy current testing executed online to detect longitudinal defects and wall thickness anomalies per EN standards.
Dimensional Control: Laser micrometer scanning integrated with digital multi-point verification for OD, ID, and concentricity.
Mechanical Validation: Tensile testing, yield strength verification, elongation measurement, and flattening/flaring tests conducted per production lot.
Metallurgical Evaluation: Grain size analysis and microstructure checks via optical microscopy.
Material Certification: Mill Test Certificates (MTC) supplied in strict accordance with EN 10204 3.1, establishing full heat-number traceability from raw billet to finished tube.
Applications
Fluid Power & Actuators: Hydraulic cylinder barrels, pneumatic cylinders, and high-pressure fluid transfer lines.
Automotive Drivetrains: Propeller shafts, steering column components, axle tubes, and high-pressure fuel rail sleeves.
Industrial Machinery: Precision bearing rings, textile spindles, heavy-duty conveyor rollers, and mechanical guide sleeves.
Energy Infrastructure: Heat exchanger tube components and industrial instrumentation lines.
Customization & Supply Chain
Custom Geometry:
Non-standard outer diameter-to-wall thickness ratios engineered upon review of engineering drawings.
Precision Cutting & Machining:
Multi-head cold sawing lines offering custom fixed lengths down to ±0.5 mm with deburred, chamfered ends and squareness within 0.5°.
Anti-Corrosion Protection:
Internal rust-preventive oil application and external phosphating; heavy-duty VCI (Volatile Corrosion Inhibitor) wrapping designed for maritime export transit.
Packaging & Logistics:
Steel-strapped hexagon bundles, wooden crating, or robust woven wrapping to prevent transit bowing or impact deformation. Minimum Order Quantity (MOQ): Typically 2 metric tons per size for standard grades; custom dimensions evaluated individually.
FAQ
Q: What is the practical difference between +C and +N delivery conditions under EN 10305-1?
A: +C (BK) tubes are in the cold-drawn hard condition, offering maximum yield strength with minimal ductility, utilized when no subsequent bending or severe forming is required. +N (NBK) tubes undergo controlled normalization after drawing, resulting in a homogenized micro-structure, superior elongation, and optimal machining stability.
Q: Can you supply tubes cut to exact fixed lengths for automated assembly?
A: Yes. Our high-speed cold sawing centers cut tubes to exact fixed lengths from 500 mm up to 6,000 mm, maintaining length tolerances within ±0.5 mm and clean, square, burr-free ends ready for welding or threading.
Q: What test reports are shipped with the order?
A: Every shipment is accompanied by a Mill Test Certificate (MTC) conforming to EN 10204 3.1. It validates chemical composition, mechanical property test data, heat treatment records, and NDT compliance results linked directly to the heat numbers stamped on the tubes.
Q: How do you prevent oxidation and rust during long-term ocean freight to North America or Europe?
A: Both inner and outer surfaces are coated with a protective dewatering rust-preventive oil film. For containerized or break-bulk ocean freight, bundles are wrapped in moisture-barrier plastic sheeting and secured to prevent atmospheric moisture exposure.
Q: What is the typical MOQ for custom steel grades or non-standard dimensions?
A: For custom dimensions or specific steel grades requiring dedicated tooling adjustments, the minimum order quantity generally starts at 3 to 5 metric tons per size. Regular stock dimensions have a flexible MOQ starting at 1 metric ton.
Q: What international manufacturing standards are implemented on your lines?
A: Production and quality control protocols strictly comply with DIN EN 10305-1 (seamless cold drawn precision steel tubes), DIN EN 10305-4 (welded cold drawn tubes for hydraulic systems), and ASTM A519 (carbon and alloy steel mechanical tubing).
Request a Quote
To expedite your formal quotation, please provide the following technical specifications to our engineering and sales desk:
Steel Grade & Standard (e.g., E355, AISI 1020, EN 10305-1)
Dimensions (Outer Diameter × Wall Thickness or Inner Diameter, in mm or inches)
Delivery Condition (e.g., +C, +N, +SR)
Quantity (Total metric tons or total meters)
Special Requirements (Fixed cut lengths, specific surface finish, packaging requirements)
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