NIPPON KINZOKU CO., LTD. (Headquarters: Minato-ku, Tokyo) announces the launch of a sample supply system for its “Internally Polished Capillary Tubes.”
These tubes feature significantly enhanced internal smoothness in ultra-small sizes, realised through the development of the company’s proprietary internal polishing technology.
We are currently proceeding with the design and construction of manufacturing equipment, aiming for mass production within fiscal year 2027.
Background: Rising Demand for “Ultra-Small Diameter x Ultra-Smooth Internal Surfaces”
We have previously developed high-precision, small-diameter tubes made of austenitic stainless steel with an internal diameter (ID) of 0.50mm and internal surface roughness of ≤ 0.5μm, which have been highly evaluated across various industries.
In recent years, the advancing performance of analytical, medical, and biotechnological equipment has driven a rapid surge in demand for capillary tubes with even smaller diameters and smoother internal surfaces. To achieve a level of internal roughness in the 0.30mm ID class that was previously unattainable through conventional manufacturing methods, we have established our proprietary internal polishing technology.

Key Features of “Internally Polished Capillary Tubes”
Leveraging our advanced precision processing technologies, this product delivers the following superior characteristics:
- Unmatched Internal Smoothness: Dramatically reduced internal surface roughness from the conventional Ra ≤ 0.5μm to Ra ≤ 0.2μm.
- High Dimensional Precision: Achieves a tight internal diameter (ID) tolerance of ±0.03mm across ultra-small sizes ranging from 0.30 to 0.70mm.
- Excellent Corrosion Resistance: Constructed from high-grade austenitic stainless steel, these tubes are ideal not only for analytical instruments but also for diverse applications including medical/biotech equipment, semiconductors, and high-purity gas supply systems.
Summary of Sample Supply
- Steel Grades: Austenitic stainless steel (e.g., SUS304, SUS316L)
- Available Sizes: Outer Diameter (OD) 1/16″ (1.59mm); Internal Diameter (ID) 0.30–0.70mm
- Internal Surface Roughness: Ra ≤ 0.2μm
- Product Form: Straight tubing (Maximum length: 500mm)
More related news:
NIPPON KINZOKU Launches Insulated Stainless Steel FI Finish
Tokyo Metropolitan Government Selects Nippon Express for Sustainable Aviation Fuel Project















