Micron-Level Control From Swiss-Type Lathe Machining To Injection Molding And Assembly

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Although disposable catheter needles fall under the category of low-cost consumables, their manufacturing precision requirements reach the level of high-end precision medical devices. For a mature disposable catheter needle manufacturer, core competitiveness often lies in integrating traditional machining with precision injection molding, surface treatment, and cleanroom assembly into a traceable and scalable intelligent production line.

• Step 1: Raw material selection and tube pre-treatment. High-quality disposable catheter needle manufacturers directly source bright-drawn medical-grade stainless steel seamless or welded tubes, requiring the base material to be free of inclusions and deep scratches, as subsequent electrolytic polishing cannot correct structural defects. Some high-end production lines use 316LVM (vacuum-melted) stainless steel or L605 cobalt-chromium alloy, balancing brightness and biocompatibility.
• Step 2: Precision turning on a sliding headstock/Swiss-type lathe. This is the core process for machining metal components. Taking the Japanese Citizen Cincom L12-1M7 as an example, this type of equipment can complete multiple operations in a single setup-including precision external diameter turning, internal diameter reaming, side hole drilling, thread rolling, and end chamfering-on stainless steel tubes. A key feature is its synchronized deburring function, which immediately removes burrs from drilled holes using forming tools or rotating brushes right after drilling, strictly controlling burr height to less than 0.01 inches (approximately 0.25 mm) to prevent sharp burrs from cutting abdominal tissue or snagging sutures during insertion. Dimensional tolerances for entire batches are maintained within ±0.01 mm, ensuring precise interference fit between the sheath and sealing components.
• Step 3: Electropolishing. After turning, the stainless steel sleeve is immersed in a specialized electrolyte solution, and a direct current is applied to dissolve microscopic protrusions on the anode (workpiece) surface preferentially, resulting in a uniformly removed mirror-like layer approximately several microns thick. This process not only enhances brightness but, more importantly, passivates the surface, eliminates microcracks, reduces bacterial adhesion, and minimizes friction resistance during reciprocating motion of instruments within the sleeve. It is a critical surface treatment method used by disposable sleeve needle manufacturers to ensure clinical safety.
• Step 4: Ultrasonic Cleaning. High-frequency 40kHz sound waves generate cavitation bubbles in the cleaning solution, whose micro-explosion effect thoroughly removes residual cutting fluid and metal dust from pores and side holes. Compared to mechanical brushing, ultrasonic cleaning is non-contact and non-abrasive, capable of reaching micron-level dead zones, making it the final cleaning method required by ISO 13485 for metal components.
• Step 5: Medical Injection Molding and Metal-Plastic Integration. Injection molding workshops are typically equipped with injection machines rated at over 100 tons, using medical-grade materials such as dried polycarbonate (PC), acrylonitrile butadiene styrene (ABS), nylon, and liquid silicone. Transparent tips require high-flow PC (such as Makrolon 2458 or Lexan HP1 series), with mold design focused on controlling shrinkage, weld lines, and vacuum voids. Some single-use catheter needle manufacturers use aluminum molds for rapid prototyping (delivered within 24 hours), while production molds are made from pre-hardened steels like S136. The molded parts are integrated with metal sleeves through press-fitting, hot riveting, or snap-fit mechanisms to achieve adhesive-free assembly, eliminating the risk of residual adhesives.
• Step 6: Assembly and packaging in a Class 100,000/Class 10,000 cleanroom. Key sealing components (duckbill valves, petal valves, spring covers) are assembled using semi-automatic equipment within ISO Class 7 or 8 clean areas to minimize particulate and biological contamination from human contact. Finished products undergo 100% visual inspection, then are placed into Tyvek thermoformed trays and sealed in aluminum foil pouches for sterilization.

This end-to-end process-from Citizen's precision machinery to EP/UClean and injection molding integration-forms the manufacturing foundation that distinguishes modern disposable catheter needle factories from workshop-style production, enabling them to pass CE/FDA and NMPA certifications in