Assembly - January 2009 - (Page 22) QUALITY One assembler uses machine vision to inspect dialysis filters passing by at 400 millimeters per second. in ASSEMBLY Vision Systems Ensure Quality of Medical Devices M ■ By John Sprovieri Editor edical devices pose a special challenge for inspection technology. They’re produced at high volumes—and thus, high speeds—yet every assembly must be perfect. No defects can be tolerated. What’s more, the inspections often require precise measurements of very small features. In short, medical devices are the perfect application for machine vision. A case in point—no pun intended—is a needle inspection system at the B. Braun Medical Inc. assembly plant in Penang, Malaysia. Equipped with a high-resolution vision system from PPT Vision Inc. (Eden Prairie, MN), the system inspects more than 60 different needle assemblies ranging from 25 to 100 millimeters in length. The system takes several measurements of each assembly, including the length and insertion depth of the needle, the straightness of the needle, and the bevel angle of the tip. Depending on the size of the assembly, the camera captures up to eight images along the length of the needle, then stitches them together before a final measurement is made. A precision reference plate is positioned next to the needle to provide stitching references. The final measurements are accurate to ±10 microns. The inspection system includes a precision indexer, vibration-isolating mounts and special shields to minimize interference from exterior lighting. Another medical device assembler uses a pair of smart cameras from PPT to inspect dialysis filters. The filter is a cylinder molded from clear or purple plastic. A small tube, or standpipe, protrudes from either end. The vision systems check for the presence of a polyurethane filter material near the top of each standpipe. Filters move past the cameras in parallel pairs. Each camera inspects one standpipe at a time. After Quality Endures. We shipped the first Alpha Series Cam Indexer on September 29, 1997. ZERO replacement cam followers have yet been shipped. FR BH Series Base Machine EE 2-Y WARRANEAR T Y! NEW! Alpha Series Table Indexer GY Series Pick & Place ED Series Shaft Output ServoDex Roller Gear Technology Largest cam follower sizes in the industry with unmatched accuracy. 10655 State Route 47 • PO Box 4338 • Sidney, Ohio 45365 Phone: (937) 498-4901 • sales@sankyoamerica.com www.sankyoamerica.com 22 ASSEMBLY / January 2009 www.assemblymag.com http://www.sankyoamerica.com http://www.sankyoamerica.com http://www.assemblymag.com
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