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December, 2011


Adding Speed and Quality to Ultra-Clean Silicone Molding


By Jeffrey A. Bourque, Marketing Communications Manager, Nikon Metrology L


ocated in Chicago’s western suburbs, FMI produces molded silicone components for med-


ical applications. Intricate features and key dimensions of tiny silicone prototype and (pre-) production parts are measured optically using a Nikon Metrology iNexiv system. FMI engi- neers say that investigating parts under Nikon optics and illumina- tions result in superior digital imag- ing that guarantees high accuracy and Gage R&R numbers, despite the typical light glow covering the trans- parent silicone material. Automatic iNexiv inspection


jobs triple measurement productivi- ty, slash operator overhead and elim- inate human error, resulting in a payback time of less than three months. According to FMI, Nexiv’s solid reputation in the medical device industry increase the trustworthi- ness of the qualification/validation reports they generate for the FDA and OEMs. At its standalone manu- facturing facility in Elk Grove Village, Illinois, FMI produces diverse implant grade and disposable molded silicone parts. Long-term implantable silicone


parts are used in medical devices (pacemakers, defibrillators, heart


A world-class medical silicone company, FMI


houses clean rooms, fully equipped for silicone mixing, molding,


inspection and packaging operations.


valves, etc.) designed for prolonged or extended service. Other silicone items are used in sealing surgical instru- ments, neuromodulation devices, oph- thalmic systems, and other medical devices. Because a majority of FMI silicone products are implanted in the body, the FMI facility houses ISO class 5, 6 and 7 clean rooms, fully equipped for silicone mixing, molding, inspection and packaging operations.


Fine-Tuning Part Concepts As a medical silicone company,


FMI complies with qualification


processes that ensure silicone materi- al cleanliness, part shape integrity and the lowest


Important in this regard is the compa- failure rates.


a silicone header part of a pacemaker system, to shorten the time between prototype and production. The head- er part goes on top of a pacemaker


ments fully automatically. “Defining an inspection job fol-


lowing our own measurement tech- niques is easy and very similar to setting up a macro. Automatic inspection takes a jump start with intelligent search capabilities and pattern recognition, which automati- cally spots the header part position and orientation. In the automatic inspection job we also included wall thickness measurements, a unique capability offered as part of the Nikon AutoMeasure


software.


Thanks to automatic iNexiv inspec- tion using fast stage controls, we were able to reduce the start-to-shelf time for the pacemaker header part from 4 days to 1 day and a half!” Sant says that pre-production


The Nikon Metrology iNexiv system generates high-quality images of difficult-to-measure silicon samples.


ny’s choice of the tabletop iNexiv sys- tem from Nikon Metrology, a high- performance CNC precision video measuring system. FMI demands an optical system because silicone parts are too soft to be measured using a touch probe. Fairly large specimens can be measured with the Nexiv sys- tem because it has a 250 x 200mm stage and a 200mm z stroke. “It is night and day compared to


our other vision system,” said Harold Sant, Engineering Manager for FMI, Inc., when looking at the first images produced by the iNexiv vision sys- tem. “The new Nikon inspection sys- tem generates overwhelmingly clear and pinpoint-sharp images of diffi- cult-to-measure silicon samples. Silica-based elastomeric rubber material attracts light and has a characteristic mystifying glow, but the iNexiv sees right through it. We have quickly come to trust the sys- tem, because it generates a superior digital image to measure from.” Inspection is critical to FMI’s


Part Development & Prototyping (RPD) programs. Recently, the com- pany was contracted to manufacture


assembly and bundles all leads and connections. “Based on elaborate iNexiv measurements performed on different cuts, our engineers fine- tuned the header part concept to ensure optimum moldabili- ty. Low-distortion optics and high-intensity white LED illu- mination provided superb imaging that left no room for any operator misunderstand- ings. Even the header’s intri- cate features could be investi- gated easily without requiring any re-checks. We used image magnification up to 20X, which is way below iNexiv’s maximum magnification of 120X.”


Auto Inspection Economics


Measurement through-


put used to be the bottleneck when dealing with prototype qualification batches. Harold Sant says that instead of inspecting head- er parts manually, FMI engineers teach the iNexiv system to perform a number of dimensional measure-


FMI: insert molding and bonding of silicone to various substrates.


in state-of-the-art processes and equipment to deliver the sophisticat- ed ultra-clean silicone product required for surgical implantation.


Continued on page 69


and production operations at FMI probably benefit even more from automatic inspection. “iNexiv proves to be a major timesaver, considering the millions of silicone parts we pro- duce every year. The shift from man- ual to automatic inspection led to a 3- month payback time for our system, just in labor alone.”


High-Precision Measurements The complexity of the parts has


increased tremendously. FMI invests


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