Application Considerations: End users have widely varying requirements. Some applications, such as cardiac ablation, emphasize accuracy above all, while others focus on dexterity and speed. While adequate torque is often a key factor in developing surgical power tools, attention to ergonomics early in the design phase can reduce stress and manual effort for surgeons. One recent feasibility study for a surgical tool revealed that the peak static load on a clamping screw could be nearly twice the maximum clamping force indicated by the initial design. This information helped guide the team’s recommendations for the tool’s connectors and other components.
Of course, these are only a few of the many important factors that a comprehensive feasibility study should include. Collaborating with partners that have both high-precision manufacturing capability and design services to conduct feasibility studies throughout product development lends itself to a more successful product launch.
Using Established Quality Tools to Support DFM
Quality initiatives such as Six Sigma and lean manufacturing are critical to reducing variation and removing waste from the manufacturing process. Other quality tools are essential to mitigating risk in the production of medical devices. Here is a brief overview of some of them.
Risk Management: Risk management, in its various forms, focuses on all of the critical factor project elements at the onset. The Design of Experiment (DOE) is critical in evaluating or validating a component or process to be able to introduce it with assurance into use in a design and manufacturing system. This helps ensure that a product functions as intended. The DOE can prevent the need for costly testing to determine why a problem has arisen, or worse, ending up with a worthless product. The DOE, despite its high value, is often overlooked in the rush to get a project moving.
Another key risk management document is the Failure Mode and Effect Analysis (FMEA). This should always be done as part of the planning phase to help guide the team in troubleshooting and in working their way through worstcase scenario factors during the design process. (See Figure 3)
When possible, device designers should provide their suppliers and partners with an overall system FMEA in order to identify the most important product features or characteristics of the device or component, as well as design tolerances, in order to determine how to control them, and to document the process including all changes. This system FMEA provides the direct inputs for the supplier’s design failure mode and effect analysis (DFMEA).
The DFMEA will provide the basis for critical decisions from the end-user’s perspective. For example, if a surgical tool design feels awkward, or is difficult for the surgeon to hold during a long procedure, the time to address this is at the DFMEA stage.
Continuous Improvement: A continuous improvement approach can thrive in an environment where processes are often “frozen” after FDA approval or the production part approval process (PPAP). “Frozen” processes can be observed, evaluated, and documented — especially by supplier-based DFM teams with a focus on improvements. Proposed changes are then shared with the device manufacturer to show the impact on production.
“Changes should be viewed in light of risk assessment tools,” said the senior staff engineer. “They may cause delay but if patient risk is a possibility, then decisions have to focus on avoiding that, regardless of business risk. If only business risk is involved, the team has to weigh the risk, and then decide. If a supplier proposes a change, it would need to support the case for improving quality, reducing cost, increasing reliability or availability,” he added.
Kaizen: This tactic, which is Japanese for “improvement,” involves cross-disciplinary initiatives to improve processes, and lends itself well to DFM. Its success requires “on-the-floor” presence by designers, engineers, and other team members. Design engineers should participate in multi-disciplinary discussions and observe production processes, then incorporate their lessons learned into the design. One Kaizen group helped triple throughput by changing the component finishing process to minimize the time spent in prepping parts for assembly.
Kaizen initiatives may involve crosstraining, workplace organization, mistakeproofing, eliminating redundant steps, setting takt times for individual steps, and fine-tuning or even replacing older machines with newer technology.
Six Sigma: Six Sigma practices keep the focus on minimizing variation and maximizing documentation. Device manufacturers must have a commitment to verifiable data to demonstrate how well processes are working based on the DOE, FMEA, and other documentation. Six Sigma tools help control processes with work instructions and protocols to prevent deviation from customer requirements.
PPAP: Automatically applying PPAP (Production Part Approval Process) principles to every manufacturing process from the beginning gives manufacturers a benchmark to measure processes and maximize consistency.
A sound DFM plan recognizes that successfully and efficiently manufacturing a product depends on more than features, marketing appeal, or even ergonomics. Ultimately, the bestdesigned product in the world will only be successful if it can be produced within the given parameters. Consistently applying DFM principles and best practices will allow for a successful product that may be mass-produced costeffectively and brought to market with minimal delays.
This article was written by Georges Assimilalo, Chief Operating Officer and Vice President of Engineering, and Laura Goodfellow, Quality Systems Manager, at Precipart Group, Farmingdale, NY. For more information, visit http://info.hotims.com/40440-160.