Assembly - January 2009 - (Page 54) Capital Spending Cut waste tomorrow Medical Device Assembly The learning curve for lean just got shorter This anterior cervical plate system is used for shoulder and spine replacements. Illustration courtesy Stryker Corp. Eliminate waste: Prevent overproduction. Reduce inventory. Cut space requirements. Avoid errors. Optimize flow and ergonomics. Two guidebooks show how. Lean manufacturing promises benefits throughout your assembly operations. But to reap those benefits, you have to do it right. With decades of experience, Bosch Rexroth can help. We’ve packed dozens of tips into two new guidebooks: “Lean Manufacturing — Principles, Tools and Methods” and “Efficient Material Flow in Lean Production.” Download them today, or order them online at www.boschrexroth-us.com/lean. Also, check out our other lean tools, including our e-mail webletter on lean production. It’s our way to help you stay on top of all things lean. Go to www.boschrexroth-us.com/lean and download your copy or use Web Code US0405 raw materials. According to Shetty, demand for titanium mill products has increased 50 percent over the last six years. “The increase in demand is predominately due to the aerospace industry, coupled with growth in other key markets such as medical, industrial and recreation,” he points out. “In addition, only a limited number of suppliers service the orthopedic industry with these materials,” adds Shetty. “Thus, a purchaser’s ability to shop around for price is constrained. The profit margins to be gained by [supplying] the medical industry are not sufficient to attract many suppliers. [That’s why] orthopedic device manufacturers have been searching for substitute materials.” Alternatives to titanium include cobalt chrome and nitinol. Cobalt chrome alloys are widely used for orthopedic implants in Europe because they offer high strength, low weight, and excellent wear and corrosion resistance. Nitinol is a biocompatible alloy that contains nearly equal amounts of nickel and titanium. “Cobalt chrome has an advantage of being easier to work with than other traditional materials,” says Shetty. “Nitinol has been generating added interest in the market with its shape-memory properties. It also has high elastic strength.” The newest material that holds promise for orthopedic device applications is zirconium, which reduces generation of wear debris. Ceramic is also capturing a growing share of the market. In addition, polymers such as ultra-high molecular weight polyethylene are used by orthopedic device manufacturers. “They act as lubricant-like materials to allow easy movements of the metallic protheses, thereby mimicking joint movements,” says Dr. Anson Ong, a biomedical engineering professor at the University of Texas at San Antonio. No matter what type of material is used to make knees or hips, two of the biggest problems facing the orthopedic device industry are the wear debris generated by metallic and polymeric materials during movement and the initial boneimplant integration with tight-fit prostheses. “Day-to-day use of artificial joints causes them to shed tiny debris and microscopic particles,” says Len Czuba, president 54 ASSEMBLY / January 2009 www.assemblymag.com http://www.boschrexroth-us.com/lean http://www.boschrexroth-us.com/lean http://www.boschrexroth-us.com/lean http://www.assemblymag.com
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