Precision cold-drawn carbon steel tubes provide tight dimensional tolerances, smooth surface finishes, and increased mechanical strength compared to hot-rolled alternatives. Manufactured via cold drawing at room temperature, these tubes reduce subsequent machining time for high-stress hydraulic, automotive, and mechanical engineering applications.
Specifications
|
Parameter |
Specification Range / Standard |
|
Manufacturing Standards |
EN 10305-1 (Seamless), EN 10305-2 (Welded), DIN 2391, ASTM A519, ASTM A179 |
|
Steel Grades |
E235, E355, ST35, ST45, ST52, AISI 1018, AISI 1020, AISI 1045 |
|
Outer Diameter (OD) |
$6\text{ mm}$ to $355\text{ mm}$ |
|
Wall Thickness (WT) |
$1\text{ mm}$ to $30\text{ mm}$ |
|
Standard Lengths |
$5.8\text{ m}$, $6\text{ m}$, or custom cut-to-length up to $12\text{ m}$ |
|
Delivery Conditions (Heat Treatment) |
+C (Cold drawn / hard), +LC (Light cold drawn), +SR (Stress relieved), +A (Annealed), +N (Normalized) |
|
Surface Finish |
Bright, oil-coated, scale-free internal and external surfaces |
Material & Manufacturing
Material Selection
Raw materials are sourced from primary steel mills with strict chemical composition verification. Each incoming batch undergoes spectrometer testing to confirm carbon, manganese, silicon, sulfur, and phosphorus limits against ASTM and EN standards before release to production.
Manufacturing Process
• Surface Preparation: Hot-rolled base tubes undergo acid pickling and phosphating to remove scale and establish a solid lubricant carrier film.
• Cold Drawing: Tubes are drawn through tungsten carbide dies and over mandrels, reducing cross-sectional area and cold-working the grain structure for enhanced tensile strength.
• Thermal Treatment: Continuous protective-atmosphere roller hearth furnaces relieve internal residual stresses and adjust elongation properties according to target delivery conditions (+SR, +N).
• Straightening & Sawing: Multi-roll precision straighteners secure axial straightness within $1.5\text{ mm per } 1000\text{ mm}$, followed by automated cold sawing with burr-free ends.
Quality Inspection & Mill Capabilities
Testing Protocols
• Dimensional Monitoring: Laser outer diameter micrometers and internal air gauges track continuous tolerances throughout the drawing process.
• Non-Destructive Testing (NDT): $100%$ eddy current testing inspects full tube lengths for surface and internal discontinuities.
• Mechanical Validation: Tensile testing machines measure yield strength, tensile strength, and elongation; hardness testing confirms heat treatment compliance.
• Traceability: Every shipment includes an EN 10204 3.1 Mill Test Certificate (MTC) detailing actual melt and test results.
Mill Capacity
Our manufacturing facility operates $6$ cold-drawing benches ranging from $50\text{ tons}$ to $350\text{ tons}$ and protective-atmosphere annealing lines. Annual production capacity reaches $45,000\text{ metric tons}$, ensuring stable volume support for recurring global OEM schedules.
Applications
Hydraulic & Pneumatic Cylinders:
Honed or roller-burnished tubes delivering low friction and high burst-pressure resistance for industrial actuators.
Automotive Engineering:
Applied in steering columns, propeller shafts, fuel rail systems, and shock absorber components.
Mechanical Machinery:
Utilized for high-strength rollers, bearing sleeves, gear blanks, and structural machine frames.
Fluid Systems:
High-pressure fluid transfer lines requiring consistent wall thickness and clean internal surfaces.
Customization & Supply
Dimensional Customization: Non-standard metric and fractional sizes manufactured to customer engineering drawings.
End Finishing: Square cut, bevelled ends, threaded profiles, or customized deburring.
Packaging: Coated with exterior/interior anti-rust oil, bundled with high-strength steel strips, and packed in heavy-duty woven bags or custom wooden crates for safe ocean freight.
Logistics: Located near major export ports with flexible shipping terms (FOB, CIF, DDP).
FAQ
Q: What is the practical difference between +C and +SR delivery conditions?
A: +C (cold drawn / hard) condition retains high yield strength with minimal elongation, ideal for direct structural use where no further bending is required. +SR (stress relieved) condition undergoes controlled thermal treatment to eliminate residual drawing stresses, preventing dimensional distortion during subsequent machining (such as turning or deep-hole drilling).
Q: What are your standard dimensional tolerances?
A: Standard outer and inner diameter tolerances comply with EN 10305 specifications (typically $\pm0.08\text{ mm}$ to $\pm0.15\text{ mm}$ depending on dimensions), ensuring seamless integration into your assembly lines.
Q: Can you supply tubes cut to exact fixed lengths?
A: Yes. Precision cold-sawing achieves fixed-length tolerances within $\pm0.5\text{ mm}$, eliminating secondary cutting operations at your plant.
Q: Do you provide official Material Test Certificates?
A: Yes. Every order ships with an EN 10204 3.1 Mill Test Certificate specifying chemical analysis, mechanical performance data, and heat lot numbers.
Q: What is the minimum order quantity (MOQ)?
A: MOQ depends on specification and steel grade. Standard production runs start at $2\text{ metric tons}$ per item; custom alloy grades or non-standard dimensions typically require $5\text{ metric tons}$.
Q: What corrosion protection is applied for export shipping?
A: All tubes receive an application of rust-inhibiting protective oil and are wrapped in moisture-resistant woven packaging designed to withstand long-haul maritime transport.
Request a Quote
To receive a formal quotation within 24 hours, please provide the following technical details to our engineering sales team:
Steel Grade & Standard (e.g., EN 10305-1 E355, AISI 1020)
Dimensions (Outer Diameter $\times$ Wall Thickness $\times$ Length)
Delivery Condition (+C, +SR, +N)
Required Quantity (Tons or pieces)
Destination Port
[ Submit RFQ / Contact Engineering Sales ]
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