When a Medical Part Requires a New Process
These parts provide a sense of the size and the wide range of micro injection molded parts that Makuta Technics manufactures. Photo courtesy of Makuta Technics.
Two suppliers to the medical device industry–a custom extruder and a micro-injection molder–have developed innovative techniques to tackle tough parts manufacturing challenges.
By Mark Langlois
Medical OEMs' demands on high quality custom manufacturing firms are so great that they have inspired some industry-leading suppliers to develop new manufacturing processes or technologies to meet these exacting customer needs.
At Putnam Plastics, engineers led the 33-year-old medical extrusions firm, based in Putnam, Connecticut, into new manufacturing techniques and materials to meet the demands of OEMs that asked for smaller parts and higher quality. For medical parts used inside a patient's body, failure isn't an option. Putnam Plastics manufactures tri-layer extrusions via its trademark Total Intermittent Extrusion (TIETM) process that eliminated problems found in other manufacturing processes. This manufacturing technique creates composite catheter shafts that provide a soft tip and a shaft that combines flexibility and stiffness, allowing for easier insertion and manipulation.
Makuta Technics Inc., a micro injection molding firm with 21 years in the business near Indianapolis, Indiana, developed a robotic and automated manufacturing process to create a medical DNA holder that measured in microns and couldn't be touched by human hands. Three competitors failed to make the part before they even attempted to reach the "untouched by human hands" standard.
Both Putnam Plastics and Makuta focus on improving their manufacturing processes to prepare for future products. But what are some of the major technical and engineering challenges these firms faced? Why couldn't any mom and pop outfit do what they do? Stuart Kaplan, who founded Makuta Technics Inc. in 1996, told Design-2-Part Magazine in a phone interview that it comes down to tolerances.
"The DNA-free requirement was impossible until we created the automation required," said Kaplan. "The secondary cutting operation has to be hands-free. Three suppliers before us never made it to the DNA part. They couldn't make the geometry. We had the expertise in mold design, automation, and processing. They (the OEM) let us know what their problems were in every area. We went all the way from development through production."
Makuta developed the robotic and automated manufacturing process that consistently met the 150 micron wall thickness, give or take 10 microns, untouched by human hands, in quantities of about 50,000 parts per quarter.
Removing Human Error from Production
Makuta runs two shifts per day lights out, so it must certify and lock-in its manufacturing tolerances to guarantee machines get it right every time. Makuta Technics is an ISO 9001-2008 certified and audited ISO 13485 medical standards manufacturing facility with a Class 8 clean room built to meet the ISO 14644-1:2015 standards. The U.S.-owned firm operates 24 Sumitomo micro injection molding machines, operating out of a 22,000-square foot factory built in 2007 in Shelbyville, Indiana.
This micro-part manufactured by Makuta Technics is used in in-vitro medical techniques. Photo courtesy of Makuta Technics.
"The parts we make are internal components that you'll never see–a valve that will fit into a syringe, for example, or gears in a laser printer cartridge. Inside the cartridge, there are all kinds of gears," said Kaplan. "We meet tolerances down to seven microns. One of your hairs is probably 60 to 80 microns in diameter."
"We have five different cells making that part–30 million parts a year, average," Kaplan said. "It's being done in 20 to 40 seconds without anyone touching it. That expertise is what attracts customers to us. You have an extremely repeatable process with less than 2 percent fallout. The parts are moved by robots; two filters make sure the quality is there. It's repeatable and high quality. We have great confidence no non-conforming parts go through."
The DNA holder is a tiny, clear vial, Kaplan explained. It might be 7mm long by a quarter inch. The wall thicknesses are extremely thin. Micro-molding isn't just about tiny, tiny parts. It's about the geometries within the overall service area that are toleranced within microns. This vial could have little to no variation in the wall thickness because it goes into a spectrometer, and variation would throw off the reading.
"There is no human interaction once the process is set up. The effort we put into a project is up front. It isn't cheaper up front. Once the legwork's done, once you put out parts for 20 or 30 days without any human input at all, that's where you see the easy work. They're managing machines but they're managing the whole plant," Kaplan said. What surprises Kaplan is that more companies don't take the time to discover the extent to which production and quality control can be automated.
Makuta Technics operates 24/7/365 with only 12 employees, in part because the second and third shifts have no people working them. The team gathers each morning to check last night's production, set up the day's work, and plan for the second and third shifts. The machines are designed to run themselves, so the workers leave by 4 p.m. Makuta Technics supplies micro parts to a variety of industries, including medical, pharmaceutical, automotive, and electronics, among others.
A growth area for Makuta is microfluidics, Kaplan said. "That is established very well in the medical device and pharmaceutical industries. Now it's starting into and proceeding into the automotive and electronics industries also." Microfluidics involves the flow of fluids, such as blood or ink, through tiny micro channels. "You make micron sized tolerances and paths to move non-viscous liquids," Kaplan said.
Customers Value Robotic Processes When They're Explained by People
To achieve its quality goals, Makuta uses computers, robots, and automated quality control devices to discard any defective parts before they reach a customer.
In terms of quality, mold development, and process development, OEMs want input and interaction with Makuta to assure that the work meets their internal quality process. Partnerships are built with time and trust,Kaplan said.
This surgical comb is micro-molded to a tiny micron tolerance between the teeth. Photo courtesy of Makuta Technics.>
"We are, particularly once the relationship is formed, proud of the partnership we have with our customers. We are absolutely open in every sense of the word to having our customers in our place, to us being in theirs, to see how what we produce is going to be absolutely the best piece the customer can have," Kaplan said. "It's built on mutual respect. The customer has got to know we're going to open ourselves up. Once that relationship is established, they're part of us. We're part of them. We've tailored our operation that way."
A challenge of relationship building is that it takes time. "It takes great people. They meet everybody in our place. We take a tour of our place. [They meet] our quality people, our shipping people, and what they hear is, 'This is what I'm doing with your product.' I say nothing. I'm the least person here," Kaplan said.
"In order for us to do what we do in a 24-hour day, we have to make sure every cycle is going to be exactly the same as the last cycle, within microns," Kaplan said. "What has to happen is we have to be certain our processes are absolutely accurate and consistent. Instead of trying to build quality into our part, we build it into our processes."
A typical die at Makuta for a micro-injection molded part is about the size of a softball or football, tiny by way of comparison to many dies that a crane moves from place to place inside a typical injection molding factory. The dies are so small that they are fragile.
To guarantee quality parts, Makuta engineers take apart every new die the company makes, and measure every part inside the die. That information is entered into a database, and wear on the die is then measured over time. Makuta warehouses die components that will wear quickly to speed maintenance.
When the size of finished parts starts to vary because of wear to the die, the worn die parts are replaced. Kaplan said Makuta tries to replace those worn parts before they lead to defective parts.
"We're dealing with microns that can make the difference between a good part and a bad part. Our mold components are so small. They're vulnerable to breaking," said Tyler Adams, manufacturing engineer at Makuta. "We will not only measure the core components. We'll measure the guide components to ensure that if we see any wear, we'll schedule maintenance before the wear happens. We won't wait for it to happen. If it wears 20 microns every 50,000 pieces, we'll replace that part before that happens."
In addition to constantly maintaining its dies, Makuta builds its quality assurance into the manufacturing process by using Cognex vision sensors to measure parts for compliance. Makuta also uses camera inspection where customers insist, but Kaplan and Adams say that setting up the manufacturing process and equipment properly, as well as taking time initially to design the part for manufacturing, pays off with consistent quality parts.
One specialty of Putnam Plastics is to braid tubing with metal or fiber that is encapsulated between two polymer layers, giving the extrusion reinforcement that improves burst pressure resistance, column strength, and torque transmission. Photo by Mark Langlois.
"We build quality into our processes. The automation means people don't have to handle parts. We have to be sure our processes are capable and consistent," said Kaplan, who explained that quality is about creating a consistent process, not about looking for defective parts. Makuta brings its engineers to meetings with the customer to make sure the die is designed properly and the part is designed for manufacturing. "[It's] not only the parts. Everybody measures the parts. We're looking at the process."
"I'd say that's pretty important to a number of our customers," Adams said. "We are required by all of our medical device customers to set up a process that is repeatable so it can run for days and weeks, and that is never touched. There is little to no human interaction. We find that to be a big advantage because most companies can't work that way."
New Technologies Raise Product Quality
At Putnam Plastics, workers create new manufacturing processes for medical extrusions to overcome failures caused by older processes. One entire company division looks constantly for new manufacturing processes and techniques.
"We invest in new technologies. We continue to push boundaries in processing," said Ryan Dandeneau, company vice president, in an emailed response to Design-2-Part Magazine. The company's smallest extrusion: 0.007-inch ID (inner diameter) with thin walls in polyimide and other materials. Putnam Plastics makes a 0.0001-inch bioresorbable coating on a 0.0009 inch wire. "The difference in our engineering team is that we employ a wide variety of engineers that work together to provide the most innovative, high-quality extrusions and catheter assemblies."
The Putnam team includes tool makers and design and tooling engineers, plus extrusion engineers, catheter engineers, plastics engineers, chemical engineers, mechanical engineers, and automation engineers. Two of their goals are "faster and cheaper." The manufacturing equipment and processes that Putnam develops belong to Putnam.
"Most of the equipment is custom and proprietary, but for a general idea: Wire drawing stations have the ability to create custom wires within two days, rather than 10-12 weeks, [and] we have automation equipment for sorting product," Ryan Dandeneau said.
A Trademarked Manufacturing Process
One process Putnam Plastics developed and trademarked is its TIETM intermittent extrusions process, which can be used to manufacture extrusions in polyester, polyethylene, polyurethane, and Pebax. Putnam developed its trademarked TIE extrusion to resolve numerous problems with existing practices.
Putnam lists four advantages to the Tri-TIETM manufacturing process over parts that are assembled using the heat shrink process. In this three-layer extrusion, the three separate tubes are extruded together at the same time, giving them unmatchable adhesion. Because it is a continuous extrusion, hinges and kinking points are eliminated. Eliminating separate, discrete components improves quality and reduces the bill of materials. Because it is manufactured as one extrusion, it is less expensive than one that people hand-assemble during a hand lay-up process.
This display of previous medical extrusions at Putnam Plastics gives visitors a quick overview of a selection of the single lumen and multi-lumen extrusions Putnam Plastics has produced in the past. Photo by Mark Langlois.
"Today our company has grown from providing world-class extrusions into a multifaceted manufacturer of high-end, complicated components and complete catheter assemblies," Ryan Dandeneau said. "Our knowledge of plastic materials and processing methods allows us to improve the function of catheters and thereby supports our mission of 'Enabling Polymer Technology to Improve the Quality of Life.'"
Tight tolerances, long a provenance of a CNC machine, are a critical consideration at Putnam Plastics, which is ISO 13485: 2003 certified. All of Putnam's parts are tiny, because they must fit inside a body.
Putnam workers routinely laser-pierce quarter-inch medical extrusions used for suture assemblies with 14 holes set 0.003 inch apart. The diameter of the hole is 0.0005 inch. Putnam is also able to apply that 0.0001 inch bioresorbable coating to a 0.0009 inch PT wire, holding a tolerance of +/- 2 microns.
Customers need magnifying glasses just to find the holes. Used in places where real estate is in short supply, such parts have roles in surgeries of the brain and heart, Ryan Dandeneau said. These holes are precisely placed to make a surgeon's job possible. Medicine, blood, or tools can be delivered to the right spot by this part.
"We go so small you can hardly see it," Ryan Dandeneau said.
One example of the company's automation and expertise is the manufacture of a drug delivery device that is two-shot micro-injection molded with a soft, over-molded TPE tip.
"Collaboration is important, and we pull from our hundreds of years of combined experience among our engineering team," Ryan Dandeneau said. Putnam Plastics makes the design process easier by offering a computer modeling system for catheters. "The advantage of catheter modeling systems is the customer gets a feel of how the catheter may perform without requiring a significant investment."
Founder Never Content with Last Year's Process
Putnam Plastics was founded by Jim Dandeneau, an engineer who earned his bachelor of science in plastics engineering from the University of Massachusetts, Lowell. He graduated and first worked for Sabin Corp. He then founded Putnam Plastics in 1984 in eastern Connecticut, near the border of Rhode Island and Massachusetts.
"I'm always driven to improve technology. I'm an engineer. A lot of our people are engineers," said Dandeneau at the company's 100,000-square-foot Putnam, Connecticut plant. Once he founded his own company, he wanted to explore the technology to discover and master more challenging manufacturing techniques and to find the limits of the envelope.
As an extrusion is produced in one Putnam Plastics white room, a worker checks it for quality and sets it on a rack. Photo by Mark Langlois.
The company operates an entire division, Advanced Development, that isn't involved in day-to-day product manufacturing. Workers in that job, sometimes called mad scientists in house, look into the future of extruded medical parts and figure out what new manufacturing techniques and skills Putnam Plastics needs to develop in the future.
"We've always gone for the high end. We always want to improve the technology. We've always been involved in co-extrusions, two and three-layer extrusions," Jim Dandeneau said.
Ryan Dandeneau, company vice president and the founder's son, took time to explain the vocabulary at Putnam Plastics starting with the word "lubricious." That is how slippery a tube is, a trait that makes it easier for a physician to slip a wire or camera into a catheter. It allows one extrusion to slide easily through another. "ID and OD" translates into inner diameter and outer diameter of the tube. The word "durometer" refers to the hardness of a plastic, and that comes into play with a tube that has a soft tip so it doesn't damage a patient's body, but a firm end so the physician can position the tip where it belongs in the body.
A tube with a single "lumen" is similar to a straw–it has one opening along the length of the tube. Those tubes are commonly used for IV, urological, or drainage purposes. A "multi-lumen" can have two or more openings the length of the tube. "Multi-lumen tubes allow for flushing and aspiration, heating and cooling, the flow of liquid and the passage of air, and the infusion of drugs while monitoring flow rates. Multi-lumen catheters have limitless potential," according to Putnam Plastics' website. A physician might send a camera down one lumen, blood down a second, and medicine down a third, all in one tiny tube.
Putnam Plastics works with a variety of plastics, including thermoplastic urethanes (TPUs) and polyether block amides (PEBA) that are used in catheter tubing and other medical device applications. Putnam uses thermoplastic polyurethanes for applications in the central venous catheter market and in some diagnostic and guiding catheter designs. Another category of note are the polyamides used in balloon catheters and for stent delivery catheters.
Parts produced by Putnam Plastics are used in a variety of medical procedures, including in-vitro fertilization, brain and heart surgery, angioplasty, stents, and on aneurysms, among others. Its parts are used in devices that deliver air, medicine, clips, cameras, blood, stents, liquids, control wires, and other medical or mechanical help to a patient.
Putnam Plastics manufactures marker bands so a surgeon knows exactly where a device is in a patient's body because the marker band fluoresces during a continuous X-ray.
Designing Durability into Medical Devices
Putnam Plastics also manufactures polyimide tubing, which can be tiny with critical characteristics necessary for neck, head, and brain intervention. Among its unique characteristics are its kink resistance, thermal stability, chemical inertness, ultra-smooth surface, and size.
"It doesn't get attacked by chemicals like thermoplastics do. If some kind of corrosive chemical goes down there, drugs or another medicine, it stays stable," Ryan Dandeneau said.
Putnam makes thermoset polyimide tubing with outer diameters ranging from 0.006 inch to 0.065 inch, with the wall thickness ranging from 0.0002 inch to 0.010 inch. This material can be reinforced to resist collapse and buckling, as well as improve burst strength and torque transmission.
"In our world, everything has to be tiny. We have very limited real estate. You have to have very, very thin walls," said Ryan Dandeneau, who earned his bachelors of science in material science engineering at the University of Connecticut and his master's degree in plastics engineering at the University of Massachusetts, Lowell.
Ryan Dandeneau worked his way up through the company ranks, including working for several years in California selling to OEMs. "We have customers come to us with a design idea. We have a huge technical base and sales team that will work with them and go through that design with him or her to come up with a solution to a problem. There are other people who do what we do, but we have a some of the strongest technology in the industry. We're working every day on different designs with different options."
"That's what we sell, our technology. We don't have a product. We're a custom manufacturer," said Ryan Dandeneau.
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