All three VABB needle components are fabricated on the Swiss-type sliding headstock lathe (Citizen L12-1M7). This machine delivers a positioning accuracy of ±0.005 mm and repeat positioning accuracy of ±0.002 mm, capable of completing composite operations including milling, drilling and thread turning in a single clamping setup.

Taking the needle tip as an example, roughly 30 minutes are required to mill three curved surfaces, yielding razor-sharp cutting edges. A 0.4531-inch flat-end square mill is fed perpendicular to the cutting path during machining to guarantee burr-free blade edges.

Product codes, batch numbers and depth graduation lines are etched onto the exterior of sample notch cannulas. A fiber laser marker (JPT brand) performs non-contact ablation with a controllable marking depth of 10–20 μm for permanent, wear-resistant identification.

Sandblasting follows: 80–120 mesh alumina particles are blasted at 0.4–0.6 MPa to create a uniform matte finish. This reduces light reflection and boosts adhesion for subsequent surface coatings.

The front end of the cutting cannula undergoes flaring to house the cutting blade, while the rear inner bore is chamfered for unobstructed tissue passage. The lathe secures tubing with specialized fixtures, and formed tooling completes flaring and chamfering in one pass, ensuring concentricity ≤0.01 mm.

Longitudinal slot milling is then finished on the same machine; slot width is matched to blade thickness with a tolerance of ±0.005 mm to ensure smooth, jam-free reciprocating motion of the cutting blade.

All stainless steel parts are first immersed in 10%–20% citric acid solution at 60°C for passivation. This eliminates free iron and forms a chromium-rich oxide film, improving corrosion resistance 3 to 5 times over untreated material.

Electropolishing is performed next, using a phosphoric-sulfuric acid blend as electrolyte at a current density of 0.5–1.0 A/cm². Anodic dissolution removes microscopic surface peaks, lowering surface roughness Ra from 0.8 μm to below 0.1 μm. Polished needle shafts exhibit a reduced coefficient of friction, minimizing trauma to patient tissue.

Post electropolishing, components undergo 15 minutes of 40 kHz ultrasonic cleaning in deionized water to strip residual polishing fluid and particulate debris. Parts are then dried in a Class 10000 cleanroom and vacuum-sealed inside double-layer PE bags.

Batch sampling is conducted for particulate contamination testing (particle count ≥10 μm ≤100 particles/mL) to verify full compliance with ISO 13485 specifications.