Unrealistic tolerances that limit the ability of the gaging method to detect nonconformances should be uncovered in the initial design

More OEMs than ever before are adopting the concept of design for manufacturability (DFM). However, most don’t realize that inspection can represent 20–40 percent or more of their final product cost. If they are not looking at Design for Inspection (DFI) in early product design stages and are not involving their contract manufacturer in the process, this can represent a huge buried cost.

Unfortunately, OEMs telling the contract manufacturer that 100 percent CMM (coordinate measuring machine) inspection is required at the end of the product run without the consideration of process risk, is common practice. The result is that the manufacturing cost goes up, the cost of the devices goes up, leading to the cost of medical care going up. What does not go up, however, is getting a higher quality product. If the contract manufacturer is cornered into an inflexible design with 100 percent final product inspection required, cost goes up substantially because they must bend the inspection process to fit the product, rather than designing the product to fit the inspection in the first place.

By not creating a product that can be easily inspected, much of the cost that was saved by initiating DFM will be spent on developing viable inspection methods. Both DFM and DFI should have equal weight very early in the product design stage. Then the product will be not only cost-effective to manufacture but also to inspect. The goal of DFI is to enhance the process so that required device inspection will actually reduce the overall manufacturing cost and not add to it. This can only be accomplished by a dedicated partnership between the OEM and contract manufacturer. The primary issue when forming this working partnership is timing. Involving the contractor early in the product development stage allows both sides to work everything in tandem at the beginning.

DFI Partnering: Taking the Product from Design to Launch

Fig. 1 — Design for inspection is most successful when implemented early in the design process.

The contract manufacturer should be selected as a partner as early as possible. This will help drive more cost-effective development, inspection, and manufacturing processes. Ideally, this needs to be done before the product design is frozen and followed throughout the design process. This way the contract manufacturer can then be part of the whole inspection and risk management process. The OEM brings design risk into the project and the contractor brings manufacturing risk into the project. Together they come up with quality planning that will mitigate the risks in the most appropriate way (see Figure 1).

DFI needs to be implemented at the earliest stage possible, well before the project is quoted. The OEM needs to supply a thorough understanding of the design failure mode and effects analysis (FMEA). This can be through critical characteristics or by sharing the risks and concerns in the beginning phases. OEMs need to provide the contract manufacturer with quality plans that at least address the design risk so that the contractor will be in a position to access process risk accordingly to create a thorough quote.

The idea of quoting a project just from a drawing does not provide enough information to be able to address the expectations of the customer from the quality point of view. This kind of blind quoting can mask the true cost of manufacturing the product, and in turn the quote may need to include added cost as protection from potential unknowns that the contractor may need to deal with during production and inspection processes.

Knowledge is king. Just knowing where the OEM opts to put the datums makes all the difference in how the contract manufacturer decides to fixture a product. What kind of a tool will they use to machine this product? How are they going to hold it? How will the handoff operation work from datum A to datum B? All are critical, and the design groups need to approach these issues together.

If the contractor can look at all options available to manufacture and inspect right from the beginning, it can theoretically eliminate the need for final inspection, because this step has validated the process and assures the contractor that it’s running within the parameters to produce an acceptable product.

To design a truly manufacturable product that can also be easily inspected, not just at the end of the line, but all the way through the process, requires that all unrealistic tolerances that limit the ability of the gaging method to detect nonconformances be uncovered in the initial design. When the tolerance window is very small, the reproducibility and repeatability of the gage consumes a major portion of the tolerance band. These unrealistic tolerances add cost, usually linked to the need for 100 percent inspection.

It is very important that OEMs’ product designers are always a part of the team. It is very common for the initial product designers to hand off their side of the project to quality and purchasing teams and then move on to the next project. It should be required that the designers see their design through the development processes down to the final the launch phases. Not following through in this manner tends to perpetuate mistakes that the designer would have caught well before they became an issue. Clear key product characteristics determined by a cross-functional team including the product designers is important.

Once the design is deemed both manufacturable and inspectable, it is important to implement both from A to Z within the full manufacturing process. Most OEMs are primarily concerned with final inspection and tend to only feel secure in releasing their products if all passed final inspection. However, if implemented correctly from the first design and following through with inline inspection processes to ensure that each stage of the product is validated, then final inspection is an easy process because no defects have found their way into the production stage. The final inspection can be easily accomplished per OEM requirements, but it’s not even necessary.

Unfortunately, cross-functional teams are not always used all the way through a project, resulting in difficulty getting answers from the original design team. This is another reason to keep the original OEM designer or design team in the partnership loop. The better interaction the OEM and contractor have combining into one collective unit for launch of a new program or platform, the higher the success rate becomes. OEMs have all used several inspection techniques in their own factories and can provide a wealth of knowledge. The same is true for the contract manufacturer, who has knowledge of customized inspections from many different customer projects. The contractor may actually find faster methods of inspection and more importantly understand the need to get quality inspection to the source of the manufacturing operation where real reactions can be made to assure that nonconformances are not produced versus nonconformances being caught at inspection later in the process.

Implementing cost-effective DFI or even DFM becomes difficult to do, expensive, and often impossible if the design is already set, tested, FDA approved.

If the process has been validated, the ongoing processes throughout each stage is being monitored, and each stage produces statistical data, there is no reason to have a final product inspection. As noted earlier, this happens only because it is an OEM requirement. But now, instead of final inspection being accomplished by a $150,000 inspection system, it could be as simple as having a visual inspection to approve the product as it moves through final production. Implementing DFI up front in the process can prevent potential issues with the product during production so when it comes to the end of the run, the product is virtually defect free.

Challenges Still Exist

It’s also necessary to look at the other side, which while slowly changing for the better, still has some quite common issues to overcome. The biggest, of course, is that often by the time the OEM brings a product to a contract manufacturer for a bid, the product design is set, tested, FDA approved, and ready to launch. At this stage, implementing cost-effective DFI or even DFM becomes difficult to do, expensive, and often impossible.

With these types of projects, the contract manufacturer must approach each as a concentrated risk. Without the ability to streamline the process up front, a great deal of additional cost comes into play. The contract manufacturer will have to bid the project higher, knowing that they may have to go after additional resources, additional gaging, additional equipment, and many as yet unknown items that can potentially arise. This is due to the unknown manufacturability issues and inspection roadblocks that may exist in a product design that has virtually been set in stone. Together, the DFM and DFI additional work required on the part of the contract manufacturer to get the job done might reach as high as adding 50 percent or more to the roll out cost of the product.

When 100 percent inspection or a high-end inspection technology is called for to meet the customer requirements, but there is no room to make changes to the product to make it easier to inspect, this becomes a high-risk venture for the contract manufacturer. If the original designer indicated that simple hand gages could be used but then it suddenly requires custom, expensive inspection equipment, costs can skyrocket. This happens all the time and is one of the key reasons to implement DFI while the product design is still in the infant stages.

The Bottom Line

The medical area is highly geared toward catching defects. The path of DFI in product development brings a whole change in perspective to most OEMs. In this new scenario, the concept is to avoid manufacturing defects in the first place, rather than to try to fix them afterward. Many times, there are opportunities to do this that are not addressed in the early stages of a design. That’s where added cost comes in, and this is where bringing the contract manufacturer into the project is a true benefit.

While it is typical for all medical OEMs to “shop the product out” to various contract manufacturers to get the best price and production capabilities, there is nothing that says the OEM can’t make early integration of DFI part of its requirements. This alone is a huge cost-saving step.

It can’t be said enough: to be effective, DFI must be considered very early in the design process. Working closely with a knowledgeable partner can help streamline bringing new medical devices to market by creating the perfect trifecta: excellent design development, excellent inspection, and an excellent manufacturing process. The result to the OEM is high-quality products delivered at reasonable cost. It benefits all medical OEMs to adopt a partnering strategy with their selected contract manufacturers to bring DFI early into the project design stage. It opens the door to a true cost-saving partnership that benefits everyone.

This article was written by Matt Schultz, Sr. Product Development Engineer, and Rod Soat, Corporate Product Quality Manager, for Orchid Orthopedic Solutions (Holt, MI). For more information, visit here .