Inside the Cleanroom: Medical-Grade Silicone Tube Manufacturing Process

Medical-grade silicone tubing sits quietly behind most medical devices, though it’s rarely the part people talk about. The tubes move fluids, gases, nutrition formulas, anesthesia mixes—basically all the things that must travel safely in clinics. When a tube bends, kinks, or leaks, the entire system feels it immediately. Because of this, the tubing production process is more like a controlled routine than a simple workshop job.

Inside cleanrooms, workers move slowly, sometimes slower than necessary, just to avoid stirring dust. Anyone who has visited one knows the feeling: the air smells a bit “dry,” machines hum steadily, and every few minutes someone is checking diameter values again. That’s how medical tubing is made—not dramatic, but steady and incredibly strict.

Key Properties of Medical-Grade Silicone Tubing

The main reason silicone is used in hospitals is its steady behavior with human tissue. It doesn’t irritate, doesn’t break down into odd chemicals, and stays flexible even after long use. A nurse pulling an IV line around a bed corner expects it not to kink, and silicone generally cooperates.

Silicone also handles temperature swings well. It remains soft in freezer storage and survives autoclave cycles that reach over 120°C. Some hospitals reuse silicone parts several times because the material doesn’t harden or crack as plastics do.

Transparency is another practical detail. Doctors watch flow patterns through the tube—whether liquid is moving too slowly, whether bubbles appear. If the tubing turns cloudy due to mixing contamination, it gets rejected immediately. Old production teams often say, “If it doesn’t look clean, it isn’t clean.”

Experience matters here. Teams who’ve worked with silicone molds and mixing for years can tell by touch whether the compound is curing too fast or flowing too thick that day—small things machines don’t always catch.

Selection of Silicone Raw Material

Medical silicone is not the same as industrial silicone used for gaskets or electronic pads. Medical-grade materials must pass USP Class VI or ISO 10993, which involve things like cytotoxicity tests and sensitivity tests. Vendors usually provide certificates, but experienced factories still run their own incoming checks because “paperwork never tells the whole story.”

Two categories dominate medical tubing production:
• LSR (Liquid Silicone Rubber): flows smoothly, perfect for injection systems, great for large orders.
• HCR (High Consistency Rubber): thicker and more elastic, ideal for compression and transfer molding.

Addition-cure, platinum-based systems remain the standard because they leave fewer extractables. Every batch is logged, sometimes with handwritten notes—even in modern factories—because traceability is required for every meter produced.

Extrusion Process – Primary Method for Continuous Tubing

Extrusion is used when long, continuous tubing is needed. LSR goes through a metering pump, while HCR passes through an extruder screw. The silicone flows through a die, and this die is the part operators argue about the most. A tiny adjustment—really tiny, like 0.03 mm—can throw off the inner diameter.

One supervisor once said, “If the die looks perfect, check again. It’s lying.” That comment usually gets a laugh, but it’s true. Straightness and roundness depend heavily on die alignment.

Modern liquid-silicone machines (liquid hydraulic press types) offer stable injection and fast cycles. They help avoid problems like banana-shaped tubing or sudden wall-thickness jumps that happen when curing fluctuates.

Production sometimes runs nonstop for hours, even overnight. Operators walk back and forth checking laser gauges, writing quick notes, and trimming the first few meters until everything stabilizes.

Molding Process – For Complex Shapes and Features

Extrusion works for straight tubes. But medical devices often need more: molded connectors, multiple channels in one tube (multi-lumen), flared ends, or odd shapes that help the tubing connect with pumps or surgical tools. All of these require molding.

LSR molding fills sealed molds by pressure. HCR molding depends on compression or transfer and gives very tough mechanical performance. Well-designed molds reduce flashing, the thin film that forms on edges. Bad molds create headaches—extra trimming, wasted material, and occasional “why did this bubble appear again?” moments.

Good shops use vacuum-assisted molding and fine-tuned heating. Even then, small rejects happen. No factory hits a real 0% scrap rate, no matter how nicely someone writes the brochure.

Post-Processing and Finishing

Once the tubing cures, trimming begins. Automated cutters slice the tubes cleanly. For catheters or surgical tools, even a slightly rough edge can cause discomfort, so the cutters are set carefully.

Some tubing gets surface treatment to reduce tackiness, especially products used in assembly lines where sticking slows workers down.

Marking is done using medical-grade ink. Regular ink flakes under sterilization, so factories avoid it entirely.

Cleaning removes leftover dust or uncured fragments. Some factories run heat cycles overnight, because silicone behaves differently after it relaxes a bit. Workers say the tubing “settles.”

Packaging is done in cleanrooms. Class 10,000 or Class 100,000 rooms are common. A single visible fiber inside the sealed bag means the operator rechecks the entire box.

Quality Control and Testing

Medical silicone product goes through repeated checks during and after production. Diameter, wall thickness, Shore A hardness, elongation, and tear resistance are tested routinely. Burst-pressure testing is essential for tubes used with peristaltic pumps.

Quality staff often use digital calipers, durometers, tensile testers, and aging machines that simulate repeated bending. Dimensional tests are usually documented by hand—another old habit that actually works well.

Biocompatibility tests follow ISO 10993 or USP Class VI. Some samples stay in incubators for days; others go through gamma irradiation or EO sterilization to verify stability. If the tubing turns yellow or stiffens after sterilization, the material is flagged immediately.

Making medical-grade silicone tubing isn’t one big step—it’s dozens of small ones that depend on experienced operators, steady equipment, and cleanroom discipline. Liquid molding setups help with precision and high output. Skilled mold makers adjust the tooling by feel as much as by measurement. Cleanroom teams handle packaging like handling fragile items, even if the tubing itself is tough.

Manufacturers such as Казинда rely on long-term silicone experience, from raw material selection to cost-focused process improvements. Fast sampling and stable lead times keep medical-device companies supplied without delays.

In hospitals, every centimeter of tubing must work. A kink, bubble, or wrong wall thickness is more than a simple defect—it’s a risk. This is why medical tubing production rarely cuts corners.

Часто задаваемые вопросы

Q: What makes medical-grade silicone tubing different from industrial types?

A: Medical-grade tubing uses platinum-cured, addition-cure silicone and meets USP Class VI or ISO 10993 requirements. It avoids harmful extractables and stays safe for long contact with human tissue.

Q: Which process is mainly used for continuous silicone tubing?

A: Extrusion. It provides smooth inner bores, stable dimensions, and the long lengths needed for medical consumables.

Q: How is biocompatibility of silicone tube confirmed?

A: Through ISO 10993 or USP Class VI testing and sterilization stability checks—cytotoxicity, irritation, sensitization, plus gamma, EO, or autoclave testing.