As minimally invasive surgery (MIS) is performed more often, the highly engineered medical devices used in MIS are in greater demand. Metal tubing, in particular, has become a significant element of new MIS devices. For instance, the MIS procedure typically starts with a metal tube piercing the abdominal wall. It is through these ports that all subsequent devices pass. Designing for manufacturability (DFM) provides economical, quick-to-market product delivery to customers, and is a key to success for tube fabricators.
The medical device industry has seen explosive growth for years, particularly of those devices required for performing minimally invasive surgery (MIS). Patients prefer MIS because it is less painful and usually involves a speedier recovery. Doctors perform it because it minimizes bleeding, scarring, and chances for infection. Hospitals favor these procedures because day surgery practices are increased. Insurance companies support MIS for all of the above reasons, which generally results in lower costs.
The highly engineered devices used in MIS are actually an assembly of numerous complex and robust components, working in unison to be part of a safe, reliable, economical, and user friendly tool. Metal is still very much the material of choice in applications where strength, rigidity, or hardness is a factor, despite its economic disadvantages to plastic.
According to the Judson Smith Company, a Boyertown, Pennsylvania based subsidiary of ATW Companies that specializes in fabricating and machining of metal tubing and assemblies used in MIS devices, manufacturability is the factor that can make or break the economic viability of a particular medical device. Although device designers may already have specifications on drawings, there are other ways to make modifications to get to an end product that is produced using a reliable, repeatable, scalable, and economical process.
Metal tubing: important component of new devices
The MIS procedure usually starts with a tube, either plastic or metal piercing the abdominal wall. It is through these ports that all subsequent devices pass. Typical devices used in the MIS process include a light fixture, camera, and instruments to conduct the particular procedure. Metal tubes are often used in the trocar for placing ports in the body as well as the structural support for many of the instruments. Metal is often the material of choice due to its strength relative to its cross sectional area. Stainless steel (300 series) is a common alloy used, due to its stain, corrosion, and rust resistant properties.
Unlike very fine hypotubes, like those used for penetrating a vein or artery, the diameter of metal tubing for minimally invasive surgery devices is usually larger, typically 1/8 to ¾ inches in diameter. There is a need to minimize the size of the port in the body, while still allowing room for the instruments to pass through, which is where metal tubing comes into play. Tubing processed to very exact tolerances provides a “skin and skeleton” for the instrument, allowing it to pass through the ports while providing a maximum amount of space for the internal working components. In some cases, the tube is also an integral part of the working components. When processing metal tubing, it is critical to meet the stringent medical quality level that complies with the orthopedic and medical device requirements contained in ISO 13485.
Another key to success is the ability to design tubes for manufacturability. Obtaining good surface finishes, tight dimensional tolerances, and going from a prototype to an economically producible volume that may number into the tens of thousands is challenging.
|Judson Smith's Machining Division manufactures complex parts for the medical device industry, while maintaining tight tolerances.|
Designing for manufacturability (DFM) can be like playing chess. The tube fabricators have to think three or four moves ahead in process development to provide economical, quick-to-market product delivery to customers. Of course that means getting involved in the early stages of design, where prototypes play an important role in the process.
Judson Smith, which manufactures custom and precision tubing products, entered the medical device market by providing heat exchange tubing for blood oxygenators in the early 1980s. By the late 80s it was producing products for major medical device OEMs and market leaders in minimally invasive arthroscopic instrumentation. Currently, more than 80 percent of Judson Smith’s manufacturing is in the medical device industry. The company meets the orthopedic and medical device requirements contained in ISO 13485, which enables it to meet FDA requirements that flow down to the supply base.
Careful step by step process improves design
“The success of the tubing portion of these complicated medical devices is improved if the tubing company is involved in the project from the initial concept to full production,” states Robert Kelly, engineering manager of Judson Smith, adding that the company relishes the design challenges of both small and large projects. “At Judson Smith, problem solving is a big part of our service, and we specialize in really submersing ourselves in the application to come up with design solutions to assist our customers moving from design concept to market.”
According to Kelly, the key steps involved in precision tubing for medical devices include print evaluation, internal discussion, quotation, and prototyping, while designing for manufacturability.
Print evaluation fosters communication and idea sharing
The first step in the process is print evaluation, which includes communication with the design engineer, open discussions on what the application is for, how to achieve the goals, and recommendations for any changes. The design engineer may have only a concept, or may have gone as far as finalized prints. At this beginning stage, the tube fabricator conducts a dialog to discuss not only what is on the drawing, but also possible solutions or alternate ways to achieve the end product.
According to Kelly, “We frequently work with device engineers early in the process to understand how our component functions in the finished device, and use our experience in the industry to offer alternatives that improve the design.”
Internal discussion and quotation process refines the design
After evaluating the print and incorporating feedback from the print evaluation stage, there is an open discussion with the customer that should embrace all facets of the manufacturing, including engineering, purchasing, production, and quality. These back and forth conversations usually center on methods and techniques to form and shape components at the lowest possible cost, while preserving process capability.
Judson Smith’s production manager, Troy Graff notes that sometimes the customer’s original design just cannot be manufactured cost effectively. Judson’s cross-functional support teams review the plans, and offer solutions based on their experience with similar parts. The company’s tool room can also build tooling and fabricate parts to assist in this process.
Prototyping the design: manufacturability is the goal
If a picture is worth a thousand words, then a prototype part is worth a million. Prototyping and short runs are important in the design process. A good prototype gives the design engineer something in their hands to touch and feel, allowing them to really get a handle on the concept.
|Judson's tube fabrication capabilities include: laser cutting / welding, reducing/expanding, bending, rolled grove, beading, flaring, notching, lancing and more.|
Judson Smith notes that manufacturing a part that is close to the concept under discussion gives the engineer a good idea of what a part looks like and how it will work in the device. If the drawing has any weaknesses, developing a prototype gives the team an opportunity to discuss the situation with their engineers and perhaps improve the design. “Engineers are receptive to this interaction, and we are usually able to get a quick turnaround for getting the prototype into their hands,” says engineering manager, Robert Kelly.
The key here is that the person making the initial prototype part is simultaneously thinking about the manufacturing process that would be necessary to make hundreds of thousands of the part. For example, the company used a DFM process as part of the development of a unique forming machine to construct a fabricated tube, which is used to pierce the skin and serve as a porthole into the body cavity for a variety of laparoscopic procedures. Along with being a design improvement, the solution provided a cost structure to support the new design, keeping the cost of goods sold to a minimum. Without the improvement, the part would have been too costly to manufacture.
Another example is a surgical device for a leading dental device manufacturer. Judson Smith has been working on a series of prototypes for a specialized tube for one of their instruments, in which clearance and spacing between components is critical.
During prototype development, Judson Smith created a variety of styles to hold the center and found some performance characteristics that were an issue—the device resonated, creating too much noise. The company experimented with different ways to hold the inner tubes apart for the outer tube that would be less noisy, and are now poised to begin manufacturing of the device.
Precision machining: another piece of the device puzzle
In addition to the tubes used in the minimally invasive medical devices, precision machining of complex parts and assemblies, while maintaining tight tolerances is an industry focus. Precision machining includes orthopedic instrumentation and implantation, such as knee and hip replacements, spinal surgery, trauma procedures, and more.
Given that Judson Smith performs in-house machining and tubing fabrication, the company proves proficient in manufacturing devices with both machined and tube components and assemblies, as it finds the best way to marry them together.
“Combining tubing and machining for a MIS instrument gives the customer a cost-effective way of getting an assembly, and also usually results in better lead times than using two different suppliers,” states Judson Smith’s sales and marketing manager, John Shields.
The future: unique technologies require innovative applications
The medical device industry is bursting with ideas for innovative applications that will require tubing or laser cutting. New areas include minimally invasive orthopedics devices, including those for hips, knees, and spines, as well as devices that will be used in inter-cranial cavities, such as bone shavers for the nasal and sinus areas.
|The possible configurations of bent tubes are virtually unlimited.|
The medical device industry is an area of infinite possibilities, especially for Judson Smith, which has machining tube fabrication and a broad range of complimentary process capabilities. The breadth and flexibility of the company enables its employees to draw upon numerous resources for solving industry challenges as they are presented. By keeping all the processes in-house, the company reports that it can give customers better control over project management, while ensuring one unified quality control system.
The company approaches these medical device tubing and machining projects with a customized, personal touch, and approachable work force, which is appealing to design engineers developing new devices. According to John Shields, “Our years of quality delivery and performance, combined with experience providing design development advice, quick turnaround prototypes, and assistance in design for manufacturability provides customers one place for specialized capabilities.”
Alicia Puputti is a contributing author to a variety of medical device and other industry publications. For a consultation with Judson A. Smith Company, call 610-367-2021 or email email@example.com.