28 minutes into the episode: Dr. House leans on his cane, his patient convulsing and twitching in front of him. The TV physician is annoyed that his initial diagnosis turned out to be wrong (he gets it right second time round). His assistant yells for a drug with a complicated name, and a nurse prepares it, flicking the syringe with her finger. The needle cost all of 6 cents — not that it interests anyone here on set. In the real world, it’s a different story.
Developments in industrial metal forming and welding processes sent the price of hollow stainless steel needles plunging during the middle of the last century. Doctors and hospital staff could now afford to use needles once and throw them away, instead of having to sterilize and reuse the same one over and over. This advance in hygiene has probably saved almost as many lives as the medication the needles are used to inject.
A billion needles
While no official statistics are available, we know that in Germany alone millions of hypodermic needles are thrown away daily after being used by doctors, caregivers and patients to pierce the skin. On a global scale, that figure probably amounts to over a billion. Every day. Which suddenly turns a few cents per needle into a very hefty sum indeed.
Ralf Egerer, Director of Machine and Cryogenic Systems at Nexans, tells us how he sees it: “Medical technology is expensive, even for what appears to be such a cheap product. We’re working to reduce the costs. Our aim is to halve the price of hypodermic needles in the near future!” Egerer intends to achieve this goal using NanoWema, a machine set up at Nexans in Hannover. NanoWema rolls extremely narrow stainless steel strips into ultrathin tubes and then welds them with a laser beam.
Expertise in cable manufacturing
Nexans is primarily a cable manufacturer, and a pretty significant one at that. The company, based in Paris, has over 25,000 employees and is deemed to be one of the cable giants, providing the deepsea cables, industrial wiring and telecommunications lines that connect our world. With its NanoWema concept, Nexans is applying its core business expertise to a new market.
Our aim is to halve the price of hypodermic needles in the near future!Ralf Egerer
“It’s actually not such a great leap from cables to hypodermic needles. To shield the cable bundles inside deep-sea cables against the effects of water pressure, we wrap them in thin-walled sheaths made of copper or aluminum. And so we’re used to producing long, thin metal tubes. With NanoWema, we’ve managed to refine the process so we can make even narrower, finer tubing,” says Egerer. The tubes he is referring to are 1.8 millimeters in diameter, with walls 0.05 millimeters thick.
Postprocessing is barely needed
This kind of tubing is usually manufactured using TIG welding processes. Egerer explains: “TIG systems have technical limitations in terms of the amount of steel that can be processed and the wall thickness that can be achieved. TIG-welded tubes are usually twice the diameter of tubing that has been joined with a laser, and have walls that are three times as thick. Intensive reworking is required after the TIG welding process to make the walls thinner and reduce the diameter.”
This involves pulling the thin tubing over a mandrel and forcing it through a narrower ring. The stainless steel hardens, becoming more dense and brittle. But the steel has to remain malleable for subsequent finishing processes, so the metal has to be relaxed again. To do this, the kilometer-long length of tubing is pulled through a redhot oven and heated right through.
We’re saving our customers the expense involved in subsequent processing.Ralf Egerer
“Five reductions and three annealing steps are the norm for tubes produced conventionally, which involves a tremendous amount of energy and labor,” says Egerer. “With the diode laser, we make tubes that are already close to the required dimensions, saving our customers the expense involved in subsequent processing and the large amount of space the finishing process requires.”
A welding seam five kilometers long
Nexans is one of the leading suppliers of cables and offers solutions for all areas of use. Whether in the office, energy supply, indoor technology, transport, automotive or industry – Nexans’ cables and cabling systems ensure the safe transfer of energy and data. The range extends from copper wire to hybrid leads, from sophisticated sensor cables to high-voltage cabling. The range is completed by accessories for high-quality ports and connections.
The NanoWema process starts with the machine unwinding a thin, five-kilometer strip of metal from the spool and applying a lubricant to it. In a series of steps, the machine shapes the metal into a perfectly round, open tube using forming rollers. At the end of the shaping process, the outside edges of the strip have been brought together to lie in parallel, side by side. So fine is the gap between the edges that the laser has to be incredibly precise, focusing its beam to an accuracy of 0.2 mm. Instead of tracking the seam with the laser, Nexans has developed a system for mechanically fixing the gap in place so that it is forced to pass exactly through the beam’s focal point.The machine pulls the tubeshaped metal strip through a narrow ring called the closing die. A small fin sticking out inside the ring rests in the gap, acting as a guide that keeps the seam centered as it passes along the line. The laser beam can now weld the five-kilometer seam from above in one go, without once having to adjust its focus.
As soon as the tubing has been welded, the NanoWema system immediately winds it onto a spool. After four hours the diode laser gets a short break. “We turn the laser on, pull kilometers of tubing beneath it, and then switch the laser off again. It’s that simple,” says Egerer. “But Nexan’s years and years of processing experience form the basis for making sure that it actually works. There’s no way anyone will be doing something like this any time soon.”
Twice the speed
The laser can continuously weld kilometers of tubing at rates of up to 20 meters per minute, which is twice the speed that a TIG welder can manage. What’s more, there’s no dirt build-up on the material, which has to be removed later. Welding lubricated tubing with TIG technology causes impurities due to the crusted grease that forms on the welding wire. The laser, meanwhile, simply burns the grease off.
“Laser technology has become much cheaper in the last ten years. We’re able to get significantly more kilowatts of power out of every euro we spend, with far greater efficiency,” says Egerer. “Taking all these factors into account, using diode lasers and the NanoWema process lets us produce ultra-thin tubing with unit costs that are half of the current market rate. So in the future, Dr. House’s successors won’t have to worry about the cost of their hypodermic needles.
Nexans Deutschland GmbH
phone: + 49 (0) 511 676 – 3349