Weld Failure in the Medical Device Industry
Recently, EB Industries hosted a problem solving session with a team of ten engineers from one of the largest medical device manufacturers in the US. This particular manufacturer requested our help because they were experiencing significant failures in the field of laser welded components. The engineers were justly concerned: The devices were implanted or used in surgery and failure could mean physical harm or even death to a patient as well as huge financial risk to the health care provider right on back to the manufacturer itself. However, the parts that were failing were laser welded by various third party shops not specializing in laser welding. There was not a single instance of an EB Industries welded part failing in the field, which is why they came to us, to find out what we were doing differently. After some careful data gathering and analysis, an interesting narrative developed.
A Problematic History
About 35 years ago, an entry level laser welding system cost over $300,000 and was exceptionally difficult to operate and maintain. The technology involved flash lamps, water cooling systems, large power supplies, gold plated cavities, and fixed optics laser heads. Additionally, the control systems were minimally computerized and required a highly trained operator, and the whole system needed trained maintenance personnel. This meant that only those companies that could invest in both the equipment and, more importantly, the manpower to operate the systems, could laser weld.
Today, an entry level 200 watt laser welding workstation can be had for around $15,000. Laser technology has advanced significantly and systems often come with easy-to-use fiber optic beam delivery. The result is a very low cost of entry for a system that is easy to operate. So, many companies these days get into laser welding with a minimal investment in equipment and almost no investment in training. Indeed, the concept of laser welding seems so straightforward that it’s hard to disagree with this notion. What could be more simple than pointing a laser at something and melting it?
The reality is that it is nowhere near that simple. Having a laser welding workstation doesn’t make someone an experienced laser welder anymore than buying a TIG welder from Home Depot makes someone a TIG welder that actually knows how to weld. Would a company doing commercial work in the aerospace or medical devices industry hire a non-certified TIG or MIG welder? Probably not. But many shops doing critical work have basically untrained personnel performing laser welding, sometimes utilizing traditional stick welders or even machinists as laser welders, and often that laser welding is done by hand, with minimal to no automation, resulting in an uncomfortably wide continuum of weld quality.
A Lack of Standards
In the United States laser welding training exists but is not nearly as widespread as training in other welding methods. A few certificate programs exist and cover topics such as laser welding technology, beam delivery, weld geometry, shield gases, power density, inspection techniques and such. However, these classes are often book based and do not involve hands-on practice. There are very few schools or programs offering hands-on laser welding training. If a company chooses to send employees to one of these classes the benefit can be tremendous, but often this simply isn’t done.
Because there is very little training to standards, there is very little adherence to standards in the workplace. It is hard to put into practice that which you do not know, and that which is not promulgated on the shop floor. It’s rare to see an engineering drawing calling out any requirement for laser welding other than “LBW” (the American Welding Society symbol for Laser Beam Welding). The American Welding Society does have several specifications, but they are typically not referenced. The aerospace industry is a bit ahead of most other industries in terms of standards. For example, the AWS D17.1 specification is a comprehensive document designed for fusion welding, and includes laser welding for aerospace applications, but sadly, many other high tech industries lag far behind. In fact, one of the biggest findings from the problem solving meeting was that the medical device industry does not have any specifications for general laser welding. A few large medical device OEMs have proprietary specifications, but they’re neither widely adopted nor called out. For critical pieces, such as a heart pump, for example, medical device manufacturers usually rely on part specific procedures and operators that are locked in when the part goes through the FDA approval process, but as a whole there is a basic lack of regulating and best practices within an industry that is a large consumer of laser welding services.
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