Precision Manufacturing Process Of Disposable Trocars

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Full Process from Material Selection, CNC Machining, Injection Molding to Electropolishing

Manufacturing high-quality disposable trocars is a typical composite process chain of "precision metal machining + medical injection molding + sterile packaging." The first process is raw material selection: cannula inserts mostly use medical stainless steel 304 (HRC 22–25) or high-end L605 cobalt-chromium alloy, 316LVM (vacuum melted, easy to electropolish), requiring uniform wall thickness tubing with no inclusions; transparent obturator end caps use optical-grade polycarbonate (Makrolon 2458 / Lexan HP1(R)) ensuring light transmittance > 88% and no internal stress causing birefringence that interferes with the field of view; seals are medical platinum-cured silicone or TPE; outer handles are ABS/PC alloys balancing strength and lightweight.

Metal tube processing employs sliding head precision CNC lathes (such as the Japanese Citizen Cincom L12-1M7), simultaneously completing drilling, chamfering, and side air hole cutting at both ends, with machining tolerances controlled within ±0.01 mm. Deburring and cutting are performed in the same operation to prevent errors from secondary clamping; edge and tube mouth corner radius R undergo 100% optical projector inspection. After completion, the entire batch of tubes undergoes electropolishing-electrochemical dissolution of micrometers of surface metal, removing micro-cracks and increasing surface brightness to mirror finish (Ra ≤ 0.2 μm), while passivating the surface to enhance corrosion resistance, surpassing the flawless standard achievable by mere mechanical polishing (no scratches, pitting > 0.01 inch not allowed). Subsequently, ultrasonic cleaning (typical 40 kHz frequency) utilizes cavitation effects to shake off fine debris, thoroughly purifying blind holes and inner lumens, followed by pure water rinsing and hot air drying.

Plastic components are molded by precision injection molding machines, with molds mostly being multi-cavity (8–32 cavities) high-gloss steel molds. Process parameters strictly control packing and mold temperature to prevent sink marks, bubbles, and weld lines-defects that would directly affect the optical quality of transparent end caps or the airtightness of seal valve closing lines. Metal inserts can be embedded during injection molding (Insert Molding) to integrate the cannula with the plastic base, reducing assembly gaps and particle generation. Assembly lines typically operate in ISO Class 7 (Class 10,000) cleanrooms, automatically or semi-automatically pressing in sealing valves, screwing in insufflation valves, and installing air-stop caps. Each batch is sampled for: puncture force testing (simulating abdominal wall penetration load), airtightness (pressurized to 20 mmHg, holding ≥ 30 s with pressure drop < 1 mmHg), insertion/withdrawal cycle (simulating 50 instrument exchanges for torque and resistance), pull-out strength (thread anti-extraction force), and EO residual amount (≤ 10 μg/g or per national standards). Final inner packaging uses Tyvek/dialysis paper + medical PE bags, outer boxes labeled with batch numbers and expiration dates, stored pending release.