Precision cold-drawn steel tubes engineered for tight dimensional tolerances, high concentricity, and smooth surface finishes. Built for hydraulic systems, automotive components, and precision machinery.
Cold-drawn small-diameter steel tubes are produced by drawing hot-rolled or welded base tubes through a tungsten carbide die and over a mandrel. This cold-working process increases tensile strength, hardens the material, and achieves precise outer/inner diameters and wall thicknesses.
Size Range: Outer Diameter (OD) 4mm – 60mm; Wall Thickness (WT) 0.5mm – 5mm.
Key Characteristics: Tight dimensional accuracy, bright surface finish, excellent mechanical properties, and ready for subsequent machining or plating.
Manufacturing Capability Integration: Our in-house cold-drawing lines utilize multi-pass benches and controlled-atmosphere annealing furnaces, ensuring consistent metallurgical structure and relief of residual stresses.
Specifications
|
Parameter |
Standard / Specification |
|
Size Range |
OD: 4.0 mm – 60.0 mm |
|
Manufacturing Standards |
ASTM A519, ASTM A179, EN 10305-1 (Seamless), EN 10305-2 (Welded), DIN 2391 |
|
Steel Grades |
Carbon & Alloy: AISI 1010, 1020, 1045, 4130 |
|
Delivery Conditions (Heat Treatment) |
+C (Cold worked / Hard - BK) |
|
Dimensional Tolerances |
OD/ID up to +/-0.05 mm (depending on dimensions and condition) |
|
Surface Finish |
Cold-drawn finish (Ra ≤ 0.8 μm), optional phosphated and oiled for corrosion protection. |
Material & Manufacturing
Material Selection
Material integrity starts with traceable raw steel billets and mother tubes sourced from certified mills. Chemistry verification is performed via optical emission spectrometry prior to production.
Production Process Flow
• Raw Material Preparation & Inspection: Visual and dimensional check of mother tubes; surface pickling and phosphating to remove scale and apply drawing lubricant.
• Cold Drawing: Multi-pass drawing through precision dies and mandrels to reduce diameter and wall thickness while tightening tolerances.
• Heat Treatment: Controlled protective-atmosphere annealing or normalizing in continuous roller-hearth furnaces to eliminate internal stresses and achieve required elongation and hardness.
• Straightening & Cutting: Multi-roll precision straightening to ensure straightness within 1 mm per 1000 mm, followed by automated deburring and cutting to exact lengths.
• Preservation: Anti-rust oil coating and secure bundling for international shipping.
Quality Inspection
Every production lot undergoes rigorous mechanical and dimensional verification before dispatch. Inspection records and EN 10204 3.1 Mill Test Certificates are provided with each shipment.
Dimensional Verification: Laser micrometers and air gauges for continuous inline and offline OD, ID, and wall thickness measurement.
Non-Destructive Testing (NDT): Eddy current testing performed on 100% of tubes to detect longitudinal surface and subsurface defects.
Mechanical Testing: Tensile testing (yield strength, tensile strength, elongation) and flattening/flaring tests conducted per ASTM/EN sampling frequencies.
Metallographic Analysis: Grain size and decarburization depth evaluation via optical microscopy.
Applications
Cold-drawn small-diameter steel tubes provide structural reliability and fluid containment across demanding industrial sectors:
Automotive: Fuel injection lines, steering columns, shock absorber cylinders, and propeller shaft components.
Fluid Power: Hydraulic and pneumatic cylinder barrels, instrumentation tubing, and high-pressure fluid transfer lines.
Mechanical Engineering: Bearing cages, roller conveyor shafts, spacer sleeves, and precision machined components.
Medical Equipment: Surgical instrument shafts and diagnostic equipment structural frames.
Customization & Supply
Custom Dimensions:
Non-standard outer diameters, specific wall thickness ratios, and tight tolerance bands available upon engineering review.
Cut-to-Length Services:
Precision cutting with exact length tolerances (+/-0.2 mm) and specialized deburring (chamfering/face turning).
Packaging Solutions:
Heavy-duty wooden crates, waterproof wrapping, plastic end caps, or steel-strapped bundles configured for container shipping and corrosion prevention during ocean transit.
Logistics:
Flexible shipping terms (FOB, CIF, DDP) supporting major European and North American ports.
Frequently Asked Questions
Q: What is the difference between +C and +N delivery conditions?
A: +C (Cold worked / Hard) condition retains high yield strength from cold drawing with minimal elongation, ideal for parts requiring no further deformation. +N (Normalized) condition involves heat treatment above the upper transformation point, resulting in a homogeneous, fine-grained structure suitable for bending, flanging, or severe mechanical forming.
Q: Can you supply tubes with internal burrs removed for welded tubing?
A: Yes. For our cold-drawn welded tubes (EN 10305-2), the internal weld seam can be bead-rolled or cold-drawn down to achieve a smooth internal profile suitable for fluid applications.
Q: What is your standard Minimum Order Quantity (MOQ)?
A: MOQ depends on the specific steel grade, size, and delivery condition. For standard stock sizes, smaller trial orders are accommodated. For custom-drawn sizes, MOQ typically starts at 1,000 meters per size.
Q: Do you provide EN 10204 3.1 Test Reports?
A: Yes. All shipments include standard 3.1 mill test certificates detailing actual chemical composition, mechanical test results, and dimensional inspection data.
Q: What anti-corrosion protection is applied during transport?
A: Tubes are coated with a protective layer of anti-rust oil, fitted with plastic caps on both ends to protect threads/edges, wrapped in moisture-resistant woven fabric, and secured into rigid bundles or wooden crates.
Q: What are your typical production lead times?
A: Standard stock items ship within 5 to 7 business days. Custom production orders typically require 3 to 5 weeks depending on raw material availability and heat treatment scheduling.
Request a Quote
Provide your specifications below to receive a technical review and quotation within 24 hours.
Required Parameters: Outer Diameter (OD), Wall Thickness (WT), Length, Steel Grade / Standard, Quantity, and Delivery Port.
Engineering Drawings: Upload PDF or CAD files for custom fabrication requirements.
Submit RFQ / Contact Engineering Team
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