In-Depth Analysis Of Chiba Needle Manufacturing Processes

A Full-Chain Analysis from Medical Stainless Steel Tubing to Precision Biopsy Needles

https://radiopaedia.org/articles/chiba-needle

The manufacturing of high-quality Chiba needles is a fusion of precision small metal tube processing and medical sharp instrument manufacturing, with the core lying in dimensional tolerance control (OD/ID ±0.02 mm), needle tip geometric precision, and surface quality.

Raw Material Selection

Mainstream products use 304 or 316L medical stainless steel tubes compliant with ASTM A580/A555 standards (some high-end products use nickel-titanium shape memory alloy for special flexible needle bodies). 316L contains molybdenum, offering superior corrosion resistance, suitable for long-term contact with bodily fluids. Incoming raw materials must undergo spectroscopic chemical analysis, micrometer measurement of tube diameter and wall thickness, and visual/eddy current inspection for surface defects.

Main Manufacturing Processes

1. Fixed-Length Cutting and Straightening:​ Precisely cut coiled stainless steel tubes to ordered lengths (e.g., 15 cm/20 cm), deburr both ends, and straighten the tube body to ensure straightness ≤0.1 mm/10 cm.
2. Tube Forming and Sizing (Drawing/Sizing):​ If non-standard inner diameters are required, multi-pass diamond die drawing is used for diameter reduction, with each pass reducing the diameter by 15%–25%, interspersed with bright annealing to eliminate work hardening. Final sizing achieves the target OD (e.g., 0.7 mm/0.9 mm corresponding to 22G/20G) while controlling wall thickness uniformity.
3. Needle Tip Grinding (Bevel Grinding):​ The signature process of the Chiba needle. A CBN grinding wheel grinds the bevel at a set angle (typically 20°–30°, classically 25°), requiring no micro-chipping, no burn marks, and bevel symmetry error <2°. The needle tip angle and microscopic morphology are sampled every 2 hours.
4. Surface Polishing:​ The outer surface is mechanically polished or electropolished to Ra ≤0.2 μm to reduce insertion resistance; the inner lumen is ultrasonically cleaned to remove metal debris. Some products receive hydrophilic coatings or silicone oil lubrication to improve penetration feel.
5. Hub/Sleeve Processing and Assembly:​ The needle tube is laser-welded or adhesive-bonded to a polypropylene/ABS hub. Sets include a removable stylet to prevent clogging and enhance ultrasound visibility. Scale markings are typically applied via laser marking.
6. Cleaning, Inspection, and Packaging:​ Multi-tank ultrasonic cleaning → pure water rinsing → hot air drying → particulate contamination testing (≥25 μm particles ≤100 per piece) → unobstructed patency testing → vacuum/breathable packaging → EO or irradiation sterilization → release after sterility testing and endotoxin testing.

The entire production line typically operates in an ISO 13485-certified cleanroom (Class 10,000 or 100,000 for critical stations), with each batch retained for accelerated aging and simulated use testing. Excellent manufacturers also provide OEM services customized to customer 2D/3D drawings for OD/ID/length/bevel angle/Echo-tip (ultrasound echo ring), etc.