Stainless Steel Capillary Coil Tube — Φ0.5 mm to Φ3 mm
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Overview
The Stainless Steel Capillary Coil Tube is a precision-engineered tubing product designed for micro-scale fluidic, analytical, and medical applications. Manufactured to exacting dimensional tolerances within the capillary grade range of Φ0.5 mm to Φ3 mm (outer diameter), this product represents the upper echelon of micro-tubing technology. The coil tube configuration provides a compact form factor while maximizing internal surface area and flow path length, making it indispensable in chromatographic separation systems, microfluidic devices, precision instrumentation, and minimally invasive medical catheter systems.
Produced using state-of-the-art cold-drawn and coil-winding processes, these capillary tubes exhibit exceptional surface finish quality, uniform wall thickness, and superior mechanical integrity — all critical parameters for applications demanding reliable fluid transport at micro-scale dimensions.
Material & Properties
Material Grades
- 304 (AISI 304 / SUS 304): General-purpose austenitic stainless steel offering excellent corrosion resistance and formability.
- 316L (AISI 316L / SUS 316L): Low-carbon austenitic stainless steel with molybdenum addition for enhanced resistance to pitting and crevice corrosion; preferred for medical and pharmaceutical applications.
- 321 (AISI 321 / SUS 321): Titanium-stabilized austenitic grade suitable for elevated-temperature service environments.
Key Mechanical & Physical Properties
- Tensile Strength: ≥ 520 MPa (304), ≥ 485 MPa (316L)
- Yield Strength: ≥ 205 MPa (304), ≥ 170 MPa (316L)
- Surface Roughness (Ra): ≤ 0.4 μm (electropolished finish available upon request)
- Corrosion Resistance: Excellent resistance to atmospheric, aqueous, and chemical media
- Operating Temperature Range: −196 °C to +870 °C (304), −196 °C to +870 °C (316L)
- Non-magnetic: Austenitic structure ensures non-magnetic properties (μr ≈ 1.02–1.05)
Specifications
| Parameter | Specification | Standard / Tolerance |
|---|---|---|
| Outer Diameter (OD) | Φ0.5 mm – Φ3.0 mm | ±0.01 mm (standard); ±0.005 mm (precision grade) |
| Wall Thickness | 0.05 mm – 0.5 mm | ±5% of nominal |
| Inner Diameter (ID) | Φ0.1 mm – Φ2.5 mm (derived) | ±0.01 mm |
| Coil Diameter | Custom (typically Φ10 mm – Φ100 mm) | ±1 mm |
| Coil Length | Custom (up to 50 m per spool) | ±0.5% |
| Surface Finish | Mirror polished / Electropolished / Passivated | Ra ≤ 0.4 μm (polished); Ra ≤ 0.2 μm (electropolished) |
| Material Grade | 304, 316L, 321 (custom grades available) | ASTM A269 / ASTM A213 / EN 10217 |
| Winding Tolerance | Pitch uniformity | ±0.02 mm |
| End Condition | Flush cut / Beveled / Deburred | As specified |
Manufacturing Process
The production of capillary-grade coil tubes involves a multi-stage precision manufacturing sequence:
- Hot Extrusion: Stainless steel billets are hot-extruded to produce initial tube stock with approximate dimensions.
- Pilot Drawing: Tubes are cold-drawn through successive tungsten carbide dies to achieve precise outer and inner diameters within the capillary range.
- Intermediate Annealing: Periodic solution annealing (1050–1100 °C) relieves work hardening, restores ductility, and refines grain structure.
- Surface Finishing: Mechanical polishing, chemical polishing, or electropolishing is applied to achieve ultra-smooth internal and external surfaces, minimizing flow resistance and particle adhesion.
- Precision Coil Winding: Tubes are wound onto precision mandrels using CNC-controlled winding machines to ensure uniform pitch, consistent coil diameter, and minimal mechanical stress.
- Passivation: Final passivation treatment removes free iron and enhances the passive chromium oxide layer for superior corrosion resistance.
- Quality Inspection: Each batch undergoes dimensional verification (optical measurement), wall thickness ultrasonic testing, spectral analysis, and hydrostatic pressure testing.
Applications
Chromatography Columns (Gas Chromatography & High-Performance Liquid Chromatography)
Capillary coil tubes serve as the structural backbone for GC and HPLC columns, where the internal diameter and length directly determine separation efficiency and resolution. The ultra-smooth internal surface minimizes dead volume and ensures laminar flow, critical for accurate analytical results.
Microfluidics
In microfluidic systems and lab-on-a-chip devices, these tubes provide precise fluidic channels for sample delivery, reagent mixing, and detection pathways. The capillary range enables flow rates from nanoliters to microliters per minute with high repeatability.
Precision Instruments
Used in analytical balances, pressure sensors, mass spectrometers, and vacuum systems where micro-scale tubing must withstand repeated thermal cycling and maintain dimensional stability over extended service life.
Medical Catheters & Devices
316L capillary coil tubes are integral to minimally invasive medical devices including guide wires, infusion catheters, endoscopic channels, and drug delivery systems. Biocompatibility and surface smoothness are paramount for patient safety.
Quality Certifications & Compliance
- ISO 9001:2015 — Quality Management System certification
- ISO 13485 — Medical Devices Quality Management System (for medical-grade products)
- ASTM A269 / A213 — Compliance with American standards for stainless steel tubing
- EN 10217-7 — European standard for austenitic stainless steel tubes
- GB/T 14976 / GB/T 12771 — Chinese national standards for seamless steel tubes
- RoHS & REACH — Compliance with European restriction of hazardous substances regulations
- Mill Test Reports (MTR): Full chemical composition and mechanical property documentation provided with each batch
Unique Selling Points
- Ultra-Precision Dimensions: Capillary-grade tolerances (±0.005 mm) ensure consistent fluidic performance across the entire Φ0.5–Φ3 mm range.
- Superior Surface Quality: Electropolished internal surfaces (Ra ≤ 0.2 μm) minimize flow resistance, prevent biofilm formation, and eliminate dead zones in analytical applications.
- Custom Coil Configuration: Tailored coil diameter, pitch, and length to meet specific application requirements and equipment constraints.
- Multi-Grade Availability: Seamless supply chain flexibility with 304, 316L, and specialty grades from a single source.
- Medical-Grade Compliance: Full traceability and certification for implantable and contact medical device applications.
Note: All products are manufactured to order with customizable specifications. For detailed technical datasheets, material certifications, or sample requests, please contact Wenzhou Jixing Metal Materials Co., Ltd. directly. Custom geometries, special alloys, and post-processing treatments (brazing, welding, threading) are available upon request.