Case Studies: Metrology Improves Medical QA
Grace Medical Inc. (Memphis, TN) manufactures medical products for ear, nose and throat health, including prosthesis designs, drill systems, and instruments. Producing medical devices that are safe and work correctly requires accurate measurements during their production. One of the ways Grace Medical achieves the necessary accuracy is by using a SmartScope Flash 200 benchtop 3-D multisensor measurement system from Optical Gaging Products (OGP, Rochester, NY) for quality assurance and to help keep production levels high.
Founded in 1996, Grace Medical manufactures devices that are used in the disciplines of ophthalmology-the diagnosis and treatment of disorders of the eye-and otolaryngology-treating the ear, nose and throat. Its otolaryngology products are sold under the Grace Medical brand name, while precision miniature devices called punctum plugs-silicone plugs for treatment of dry eye that keep tears from draining away as quickly-are manufactured for its sister company, EagleVision. Grace Medical employs approximately 25 people in a 20,000-square-foot facility that is certified to ISO 13485, a quality management standard for medical devices.
The NeedThe medical devices Grace Medical produces are made of a broad range of materials from soft, malleable silicone compounds to strong alloys such as titanium. Grace Medical has the ability to produce precision-molded, flash-free silicone parts-free of excess material attached to the molded product-with core pins as small as 0.002 inch and overall lengths as small as 0.01 inch that require accurate measurement. The titanium implants made by Grace Medical have complex shaft geometries on surfaces as small as 0.008 inch in diameter.
Prior to implementing the SmartScope Flash 200 system, Grace Medical performed measurements using an optical comparator, hard gages and other dial indicators that president and founder Tony Prescott describes as estimators. They required interpretation by skilled operators, which made them slow to use. Prescott and his team initiated the search for new measurement and inspection equipment to improve compliance with FDA regulations regarding quality measurement and documentation, and to increase throughput of the inspection process.
The SolutionToday, the SmartScope Flash 200 system performs those measurements in seconds rather than minutes. Parts are measured with higher accuracy and full automation, and measurements are displayed graphically in real time. “The OGP system allows operators to instantly identify visual anomalies and quickly respond,” says quality engineer Diane Holton.
The SmartScope Flash 200, a compact measuring system with an 8 by 8 by 6 inch measuring range, was chosen based on a review of system capabilities by local OGP representative D&H Metrology (LaVergne, TN). Harvey Rath of D&H subsequently served as programming, trainer and setup consultant for implementation of the system into the manufacturing process at Grace Medical. The implementation team at Grace Medical included validation engineer Joe Miller, programmer Lucas Hines, Holton and Prescott. QA/Regulatory vice president Jeff Cobb supervised the project.
Evolving NeedsMedical device manufacturing has ever-increasing demands for new materials with tighter specifications. As Grace Medical added other new manufacturing technologies, its measuring needs evolved, creating new priorities for its metrology system. For example, Swiss-style turning machines, once used mainly by watchmakers, have gained broader acceptance by medical engineers for the design of components too small and precise for conventional lathes. Grace Medical had recently implemented precision Swiss machines to economically produce parts with multiple surfaces on round edges in a way that was more accurate than traditional processes. Grace Medical began using the SmartScope Flash 200 system for fully automated “lights out” qualification of components produced on the Swiss machines, which allowed work at the Swiss machines to remain focused on expanding their unique manufacturing capabilities.
Grace Medical uses advanced fourth-axis capabilities of the system to measure parts manufactured on the Swiss machines. Their SmartScope system is equipped with an optional MicroTheta Rotary indexer for fourth axis measuring and MeasureMind 3-D MultiSensor metrology software with comprehensive rotary axis calibration routines. These enhancements enable the system to automatically rotate parts within a measurement routine to easily measure anything from simple geometric forms to complex free-form shapes without operator interaction.
Continuous ImprovementGrace Medical continues to find new uses for the SmartScope Flash 200 system. Today, the system is used in a number of company operations, including product development, engineering, production, process control, QA, final inspection and quality training.
“In a production environment, the OGP system needs to be viewed and evaluated as a very sophisticated automated production device and not as a new piece of inspection equipment,” Prescott says. “Cycle times, fixturing for multiple parts to optimize up time, and quick changeover of inspection routines and tooling need to be considered. Use of the SmartScope Flash 200 system may result in changes in the production flow that will need analysis, explanation and training to ensure that maximum benefit is gained.”
Grace Medical constantly assesses and validates its machine routines, and the OGP system is no exception. Because of process improvements, 100% inspection is no longer required. Grace Medical now checks 10 parts per run in an automated routine. During the inspection process, the SmartScope Flash 200 system measures critical dimensions on parts arranged in a holding fixture. Blind holes 0.01 inch in diameter by 0.03 inch deep are measured in the Z-axis to the nearest 0.0002 inch. The system automatically generates inspection reports that are used as part of device history records.
By providing accurate measurements during production, the system helps ensure safety and functionality of the products manufactured at Grace Medical. To date, use of the measuring system has cut inspection times more than tenfold-from 10 minutes per part to just 40 seconds-while simultaneously improving quality control. “We’re measuring more dimensions than we were before,” Prescott says.
Benefits• By providing accurate measurements during production, the SmartScope Flash 200 system helps ensure safety and functionality of the products manufactured at Grace Medical.
• To date, use of the measuring system has cut inspection times more than tenfold-from 10 minutes per part to just 40 seconds-while simultaneously improving quality control.
• The system is used in a number of company operations, including product development, engineering, production, process control, QA, final inspection and quality training.
Optical Gaging Products