| Done any remodeling lately? If you have, you’ve been faced with countless choices regarding design and materials. Even a relatively simple decision such as putting in hardwood flooring requires many considerations. What type of wood? What grade? How about the stain? Should it be factory stained and sealed, or should the flooring be installed by single board, then stained and sealed in place? Ultimately, your decision is based on your requirements with regards to cost, durability, and personal style.
Now imagine the decision making process that is required to produce a medical device. We’ve been discussing this complex process during our series on medical device design utilizing the systems engineering approach, a systemized approach to product development, design, and manufacture that is used within many manufacturing arenas. Its objective is to relate the requirements for manufacture, regulatory compliance, sale, use, and maintenance of the product to specific design criteria for functionality, durability, and safety. By doing so, the systems engineering approach ensures that the product meets or exceeds all requirements. Last time we wrapped up our discussion on the Development stage of systems engineering by discussing field testing of medical devices assembled during Preproduction. Problems encountered during this phase result in a comprehensive review of the device design and instructions. When all issues have been resolved, things move on to the manufacturing phase and full commercial production. During the Production stage, engineers make continual assessments of the manufacturing process and ongoing adjustments are made to the device design and manufacturing protocol as necessary, this due primarily to changing stakeholder requirements regarding cost reduction. In the competitive marketplace, cost reduction is a never-ending quest to maintain profitability in view of changing economic and market conditions, and this must be done without compromising the quality, safety, and effectiveness of the device. For example, suppose a medical diagnostic imaging machine was designed to be fitted with a machined metal gear in one of its mechanisms. The manufacturer specifies that a $10 decrease must be made in production costs so it can continue to be sold at an acceptable profit margin. After reviewing the design, engineers discover that substitution of a molded plastic gear would reduce manufacturing cost per machine by $12. This is a common scenario, as plastic parts are often substituted for metal to save on cost. Plastic versus metal? How can that be an acceptable swap? In many cases, it can be. Mechanical stressors are analyzed, and if the plastic gears meet durability requirements as well as their metal counterpart, they are substituted. During the Preproduction phase these plastic gears are used in both lab and field testing, where they are put through the rigors of real world use. If they perform acceptably, they are made a permanent part of the device’s design and used in commercial production. Next time we’ll continue our look at the Production stage to discover another way that systems engineering can facilitate cost reduction to meet stakeholder requirements. ___________________________________________
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Archive for February, 2013
Systems Engineering In Medical Device Design – Preproduction, Part 3
Monday, February 18th, 2013| We’ve been discussing the Preproduction aspect of the Development stage of our systems engineering approach to medical device design. Last week we learned that once the medical devices produced during Preproduction are assembled, they’re subjected to rigorous testing, first in the lab, then in the real world.
Once devices produced in Preproduction pass the test in a controlled laboratory environment, it’s time to place them into field testing. The objective is to place Preproduction devices within actual working environments, such as healthcare facilities. These facilities must be willing to cooperate with design engineers during testing on a number of items, including but not limited to evaluation of product performance and clarity of instructions. In order for this to happen, design engineers must coordinate their efforts with their company’s sales and marketing departments to locate, qualify, and enlist suitable facilities. To qualify, a facility must be able and willing to put enough hours of use onto the test device to effectuate a thorough and complete analysis of its effectiveness. Depending on FDA regulatory requirements and the complexity of the design, field testing could take as little as several months or as long as several years. During field testing valuable data is gathered to enable engineers to evaluate the performance of the Preproduction devices. This data will then be measured up against stakeholder requirements. What this process might entail in a dialysis machine, for example, is that test data is analyzed to make sure all operational parameters fall within the desired range. Data would be derived from measurements of such things as the pressure of blood flowing pre- and post- introduction to the dialyzer. Measurements are dutifully recorded by engineers and field personnel onto data sheets for later evaluation back at the manufacturer’s engineering office. Persons contributing data vary widely, from healthcare facility end users and maintenance personnel, to the medical device dealer’s service technicians. End users also provide feedback to design engineers regarding the field test device’s functionality, effectiveness, reliability, and maintainability. Feedback can include specific information about things like glitches in software, unusual noises, erratic operation, breakdowns, and even difficulties encountered during repairs. If any problems are discovered with the device during lab and field testing, revisions are made. Design engineers and technical writers get back to the drawing board to rework things and find resolutions until all issues have been addressed. Only then is the design presented to stakeholders for final approval. If all goes well, manufacturing will now take over and place the device into full commercial production. We have now concluded our discussion on the Development stage of systems engineering as it relates to medical device design. Next time we’ll move on to the Production stage where we’ll examine post-production concerns. ___________________________________________
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Systems Engineering In Medical Device Design – Preproduction, Part 2
Monday, February 11th, 2013| Last time we began our discussion on Preproduction, the final aspect of the Development stage of our systems engineering approach to medical device design. This is the point at which a small amount of devices are put into actual production, then evaluated for full production possibility. It is also the final juncture at which problems will be evaluated and corrected before full commercial production can begin.
Once the medical devices produced during Preproduction are assembled, they’re subjected to rigorous testing in both a laboratory and the field. This testing is necessary to see if stakeholder requirements are satisfied. At this stage devices constructed en masse on the factory assembly line are compared to prototypes built by hand by design engineers earlier in the Development stage. During Preproduction laboratory test data is gathered and analyzed by engineers to assess how the device will hold up during actual use. Real-life conditions are simulated in the lab environment to facilitate this process. For example, lab testing of a Preproduction kidney dialysis machine can determine whether its blood pump flow rate falls within acceptable range during hundreds of hours of operation. Other factors, such as durability of materials are evaluated during lab testing. In the case of the dialysis machine, there is a component called a dialyzer that filters toxic waste from blood. Over the duration of the lab test, the material used in the dialyzer filter membranes would be inspected and evaluated for durability. Next week we’ll conclude our discussion on Preproduction to see what happens when testing is moved outside the lab environment into the field. ___________________________________________
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Systems Engineering In Medical Device Design – Preproduction, Part I
Monday, February 4th, 2013| If you’ve been following along with our blog discussion on the systems engineering approach to medical device design, you should by now be convinced that instructions are important. In fact, the meticulous instructions produced during the manufacturing, operating, and maintenance phases of the Development stage are also crucial to later stages, that of Production and Utilization. Let’s finish up our discussion on the Development stage by taking a look at its final aspect, Preproduction.
The Preproduction aspect is instrumental to nipping potential problems in the bud before the medical devices go into actual production. In the initial Preproduction stages, systems engineers coordinate with the manufacturing and purchasing departments within the company as well as outside suppliers. The goal is to acquire all parts and equipment necessary to build a limited number of medical devices on the assembly line. Subjects such as preference in molded plastic components, motors, gears, pumps, springs, electronic components, circuit boards, wire, and tubing are discussed and agreed upon. Vendors are assessed with regard to their ability to produce parts when they are needed and that meet design specifications, satisfy quality requirements, and have costs that fall within budgetary constraints. The assembly of Preproduction devices provides an opportunity for systems engineers to validate manufacturing and quality control instructions and assess the device design with regard to manufacturability, meaning, the extent to which devices can be manufactured with relative ease, at minimal cost, while maintaining maximum reliability. Devices manufactured during this aspect of the Development stage serve as a test. Are instructions clearly written? Do the device parts fit together as they should? Are parts strong enough to withstand the assembly process? Can the devices be assembled as quickly and easily as expected? If the answer is “no” to any of these questions, then the device design and instructions must be returned to the design engineers and technical writers. Heads come together to rehash things and work out the bugs. Next time we’ll continue with the Preproduction aspect of the Development stage to see how laboratory and field testing enables systems engineers to shake out any more bugs from the medical device design, operating instructions, and maintenance instructions. ___________________________________________
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