Mark Crawford, Contributing Writer09.08.16
Thanks to the Internet of Things, automation and assembly are more connected than ever before. An increasing number of assembly processes are automated. Modular or flexible automation allows for rapid scale-up, growth, and product line changes, even for low-volume production. Also, with automation becoming more affordable, a greater number of manufacturers are integrating it into assembly, maximizing production and quality and reducing operational costs.
Speed is a top priority for medical device manufacturers (MDMs). With the trend toward smaller, more complex devices, sometimes built from challenging materials, it becomes harder to maintain reliability and quality. Also, with the Affordable Care Act’s focus on outcome-based reimbursements, healthcare systems are eager to provide monitoring-type care, which is why wearables, drug-delivery devices, and point-of-care devices are on the rise. These types of devices also rely more on electronics and wireless technologies, adding another layer of complexity to the assembly process. As a result of these rapid product developments, vendors are being challenged to stay on top of technology to meet market and consumer demands.
“As medical and combination devices become more complex, including requirements such as electronic integration and combination products, we continue to see more complexity in the solutions for automated work cells,” said Al Neumann, Automated Manufacturing Systems manager for SMC Ltd., a Somerset, Wis.-based contract medical device manufacturer. “This is true for high-volume as well as low-volume products.”
More complexity typically means more parts, smaller parts, more functionality, and wireless machine-to-machine communication. Sensor and vision technologies are often needed to provide real-time data that optimizes the entire production process. This ultimately reduces costs and streamlines production by capturing performance data that is used to maximize production processes, including automation. Real-time data is essential for devising the most productive and efficient automation/assembly system possible.
“We are seeing an increased need for more real-time statistical data pertaining to the processes required for assembly,” said William Mis, vice president of sales for Arthur G. Russell Company, a Bristol, Conn.-based manufacturer of custom assembly systems and high-speed feeding systems for the medical device industry.
For example, he noted, IoT sensor data provide views into operational aspects that were not possible before. A proximity sensor once simply sensed the presence of a part; but now, when equipped with an embedded temperature sensor, it can identify a bad bearing or motor before either can create a maintenance issue.
“Smart sensors on machines is part of the Internet of Things and allows for more big-data opportunities,” Mis added. “With big data, data mining and business intelligence can offer more insight to the plant floor and recognize trends on machines and parts of machines, which improves operational efficiencies and keeps costs down.”
Experienced Partners Wanted
OEMs want to work with contract manufacturers that try to stay ahead of the game by investing in more sophisticated controls systems and improving their assembly and automation technologies to maximize quality, production, validation, and speed to market. They seek a perfect match in mindset and culture—continuous upgrades in automation and assembly equipment, automated real-time process controls, and automated feeding systems. Solutions that offer flexibility and creativity (but still with 100 percent verification and consistent, repeatable cycles) are in high demand. Finally, OEMs want this without having to ask for it—this kind of display of leading-edge knowledge makes them feel confident in moving ahead quickly with a comprehensive proposal that accelerates production.
“OEMs expect automated solutions to reduce risk and improve product performance, without sacrificing product quality,” said Keith Calvert, engineering director for The Tech Group, a Tempe, Ariz.-based contract manufacturer of medical devices. “Speed to market is still the big driver with every OEM today.”
As parts get smaller and products more complex, OEMs count on assemblers and automation providers for design guidance, especially with process development/proof of principle. Top concerns are reliability, precision, and speed. OEMs are reaching out more to contract manufacturers as advisors—not just large automation houses that have proven experience within the medical device sector, but also small equipment vendors and in-house or third-party validation experts for niche applications.
“While the majority of our business is still providing our valves, pumps, and integrated sub-assemblies directly to OEMs, we have seen an increase in our business with contract manufacturers and engineering design firms,” said Craig Occhiato, segment manager for microfluidics for Bürkert Fluid Control Systems, a Charlotte, N.C.-based manufacturer of measurement and control systems for liquids and gases for the medical device industry. “The smaller firms normally buy components and design and build complete systems in-house. Larger and medium size firms, like many OEMs, see the value in outsourcing portions, or the complete fluid handling system, to an experienced firm.”
Calvert agreed.
“Typically, our OEM customers lean toward automated assembly solutions to mitigate risk and improve efficiencies,” he said. “We are seeing a shift toward engaging with contract manufacturers and their assembly partners earlier in the development process as advisors. This helps ensure the assembly solution meets good DFM/DFA principles of repeatability and reproducibility throughout the manufacturing and assembly process.”
More Complexity, More Challenge
Assembly isn’t as easy as it used to be. For example, with the increase in the number of connected devices, there is more integration of electronics assembly, with 100 percent verification of device function. All appropriate locations on the assembly line must be protected from electrostatic discharge (ESD). Work instructions need to be completed and the operators and technicians on the line need to be appropriately trained for ESD protection.
“It is also essential that complex on-line verification tests are developed through proof-of-principle testing, and then integrated into the automation,” stated Meredith Canty, director of drug delivery systems for SMC. “The on-line verification testing then needs to go through extensive validation to ensure it is yielding the correct results.”
Packaging requirements during the assembly process flow must also be taken into account, as there could be multiple layers of packaging that include the primary pack heat-sealed bag, secondary pack custom-corrugate pack with multiple devices, and tertiary packaging—placing the custom corrugate packs into a larger corrugate box. “The placement of devices, literature, labeling, and tamper evidence must be taken into account during the various packaging steps,” she said.
Combination products also present unique challenges. For example, final device assembly equipment is seeing more integration of the primary drug product container and serialization of each device. “Many of the primary drug containers (PDC) are made out of glass and a certain percentage of them break during handling and assembly,” said Canty. This breakage must be considered when designing the automation. The machine should be as robust as possible to prevent breakage, but the automation also needs to be easily accessible for repair if needed, or cleaning if there is breakage. “It is also important to ensure the automation does not break sterility of the PDC—this could happen by moving the rubber stopper or dislodging the needle shield,” she added.
Sometimes implementing well-established standard processes still requires some creative adjustment or modification that is identified through risk mitigation and documented capability studies, in order to deliver a successful proof-of-principle endeavor. These processes are then automated and validated to current U.S. Food and Drug Administration requirements, including 21CFR Part 11 compliance, on the equipment being delivered. For example, assembling combination devices requires a higher degree of precision to avoid glue or silicone residue coming into contact with the drugs.
“With ultrasonic welding, laser welding, or glue bonding, sometimes there are characteristics in a product design that can be detrimental if processes are performed in one order versus the other,” said John Wuschner, vice president of engineering and quality for Kahle Automation, a Morristown, N.J.-based designer and builder of automation systems for medical device companies. “Other situations could be the need for special fixturing to improve reliability, or a small design change to an energy director that can be the difference between part flash/particulate and a clean robust weld.”
Developing an Automated Solution
Like design for manufacturing (DFM), planning for automation during the product design phase is as important as planning for any other segment of the manufacturing process. There are multiple stages of automation, beginning with the manual assembly stage. This knowledge is then applied to the hand-loaded automated assembly equipment (manumation). Manumation equipment can be used for engineering testing, design verification, clinical trials, and commercial launch if validated appropriately. The goal is to take the learnings from the manumation and apply them to a larger-scale assembly line for commercial scale-up. Part loading can still be conducted manually at this stage if needed, but usually, there are bowl feeders and/or tray loaders to handle parts. The final packaging also needs to be considered to determine what type of scale automation is required to keep up with the assembly equipment.
As devices become more complex, contract manufacturers and supply chain vendors work more directly with OEMs to create cost-effective solutions for proof of concept. “It’s a service we have provided for years, but now more OEMs are asking for it,” said Neumann. “This allows OEMs to verify their concept and reduce risk prior to investing in expensive equipment.”
Customers also want cost-effective automation cells that can be built within a short time frame. Products are often modified, or test requirements changed, during work cell builds. “Timelines and budgets often remain the same, so we’ve learned how to improve efficiency while building in a modular, more flexible style,” said Neumann. “Flexible work cells are more capable of adapting to product design revisions or product volumes changes.”
Sometimes for complex products, special adjustments (or even custom-designed equipment) are required to make everything work out. For example, assembling combination devices requires a higher degree of precision to avoid glue or silicone residue coming into contact with the drugs. Kahle Automation has developed higher-accuracy dispensing valves and precision mechanical placement tooling to support these processes, eliminating any splatter from valve shut-off. The new valve opens and closes without affecting the dispensing volume, or generating any minute droplets around the components.
“If specifications require a tight tolerance in glue or silicone quantity, these valves are the only choice to meet that specification,” said Wuschner. “With glue, often the specification is to guarantee acceptable adhesion [on the low side] or avoid cosmetic defects or migration of the glue into an area that is undesirable [on the high side, or with splatter]. Conditions outside this tolerance will lead to waste or possible product performance issues.”
Once a work cell has been designed, advanced sensor technologies can simplify work-cell operations. For example, some sensors can be adjusted using the work cell’s human-machine-interface (HMI). “The HMI can now provide an ergonomically convenient location on the work cell that a technician can use to safely adjust or monitor sometimes hard-to-access sensors,” said Neumann. “When a linked component is replaced, stored values are automatically downloaded to the new device, eliminating possible inputting errors. Also, many sensors look the same, yet may have very different operating characteristics; the control system will alert the technician if a replacement sensor is not exactly the same as the original.”
Injection Molding
Advanced sensor technologies can also enable highly automated injection-molding techniques, where cavity pressure transducers and vision systems are integrated into the process to ensure only high-quality parts go into the automated assembly cell. Also, as plastic medical devices get smaller and more intricate, engineers have fewer options for assembling their components. Although friction-based joining processes such as ultrasonic welding, spin welding, and vibration welding are generally fine for most assemblies, they can also generate particulate contamination, which can be a problem for some devices. Laser welding solves that issue.
“The overriding reason medical device manufacturers choose laser welding is that it’s a clean joining method,” Hugh McNair, manager of laser applications and systems at Branson Ultrasonics Corporation, a provider of laser plastic welding technology based in Danbury, Conn., said in a recent article in Assembly Magazine. Branson utilizes an infrared laser welding process that distributes the energy to the entire joint line simultaneously (in other technologies, the laser traces or scans the joint line progressively). Illuminating the entire bond line simultaneously reduces overall cycle time, enabling the technology to be considered for high-volume assembly of disposable medical devices. Depending on the application, cycle times range from 0.5 to five seconds. “We’ve done applications in as little as six to eight milliseconds per part,” said McNair.
Some medical devices have unique material requirements that affect assembly. For some materials, laser welding works well for bonding parts made from different materials, especially if they are heat-sensitive materials, or the assemblies contain sensitive electronics. For other multi-component products, or for materials that may not have natural adhesion, such as liquid silicone rubber (LSR) and thermoplastics, laser welding is not the best method. In these situations, two-shot injection molding can be used to reduce the number of parts needed for final assembly or the number of secondary steps required.
SIMTEC Silicone Parts LLC, a Miramar, Fla.-based manufacturer that specializes in LSR injection molding, has developed a new technology for manufacturing multi-shot LSR/thermoplastic/metal components. The conventional approach requires two separate tool sets—one for the silicone and another for the thermoplastic. In addition, the metal part would have required assembly with both the silicone and thermoplastic components in a secondary operation. From a cost perspective, this conventional approach requires significant investments not only in tooling, but also in assembly lines and tooling validation at various stages of production.
“Employing state-of-the-art technology, SIMTEC and its sister company, RICO Elastomere Projecting, have developed a multi-shot solution,” said Enrique Camacho, president of SIMTEC Silicone Parts. “Both the thermoplastic and liquid silicone rubber components are injection-molded, using a two-shot manufacturing process. An intermediary process facilitates the presentation of the metal part into the thermoplastic mold for overmolding. This solution enables the integration of functions and materials in a controlled environment, which in turn allows for the elimination of assembly lines while also ensuring part cleanliness and a zero-PPM rate.”
Vision-Based Inspection
Vision-based inspection systems are a must for maintaining quality and manufacturing standards. These systems can evaluate parts or products from almost any point of view or orientation. High-resolution photos can be compared to the actual geometry in imported CAD files. Visual coordinate measuring machines are also used to rapidly measure complex shapes—up to 80 or more contours can be measured in one minute or less. Parts can be inspected at any time during the production process—as a final product, or in-situ inspection as they are being produced, in real time, eliminating the need for offline inspection.
Most vision systems provide high-speed, high-definition inspection from multiple angles at the micron level, through adaptable vision sensors. Easy-to-use graphic user interfaces are operated via a touch screen. The system stores and records high-definition images and data for every product examined, allowing for real-time statistical process control, which can be used to significantly reduce future engineering and build costs.
Typical applications for machine vision systems are robot guidance, motion control part orientation, dimensional inspection pattern and/or character recognition, 2D and 3D barcode reading, label inspection, printing inspection, and quality control. For automation and assembly, this includes critical assembly steps such as height checks, flow tests, load tests, weight checks, etc. Sometimes off-the-shelf systems will work, but with increasingly complex products, some MDMs partner with vendors to create custom systems for their needs, or the automation vendor builds its own proprietary system in-house.
For example, Kahle Automation has recently developed a novel glass-defect vision inspection system for identifying printing defects, cracks, nicks, and particulate matter that inspects 360 degrees of a glass tube (one-degree resolution) at a rate of 240 parts per minute, and can be scaled for higher production. “By inspecting the glass prior to assembly, we avoid adding value to product that will ultimately become scrap,” said Wuschner. “This saves the customer money and keeps the line running at a higher efficiency.”
Moving Forward
It is often assumed that automation is only for high-volume needs. This is not the case. Automation also benefits low-volume programs by ensuring repeatability, eliminating human error, and providing 100 percent verification of each device. Automated assembly aids and testers can often be justified for low-volume needs when there is a high device value, or when test results during assembly are critical. “Many programs start out as low volume before the product line is established,” said Neumann. “This is a perfect time to implement ‘bridge’ work cells that offer more positive assemblies than purely manual operations, and allow us to plan for the more complex automated cells, which will be incorporated later.”
Electronic components, and vision hardware and software, are constantly improving. To stay on top of technology advances, forward-thinking companies continue to bring creativity and innovation into the next-generation platforms they create. For example, Bürkert has built in-house, value-add capabilities (valve/pump/sensor/manifold assemblies) tailored to its customers’ needs. These custom systems are often the basis for the company’s next-generation standard/off-the-shelf products and technologies.
“Our pneumatically driven pump/dosing systems are a good example,” said Occhiato. “Positive displacement dosing at volumes from 50 uL to 1,500 uL per dose [1-2 percent accuracy] are standard options for cleanable units or single use. While the technology is not new, the design and the manufacturing can be a challenge, draining time and resources. Our standardized modules and experienced team offers our customers this alternative dosing technology to consider that offers many benefits over traditional methods.”
Many process problems can be mitigated through the use of small design changes, without affecting the functionality of the product. “The key is to involve the prospective automation vendor early in the design process, where principles can be proven and hypotheses of improvements can be tested before the choices become costlier,” said Wuschner. “For example, a simple chamfer on a mating component can be the difference between an easy assembly and a difficult one. Also, symmetry of components that enable multiple orientations allow for more possibilities for first-time success.”
Neumann agreed that early involvement between the OEM and the assembler/automation vendor is crucial. A recent complex tester, he noted, was designed and built at SMC and required communication with the customer’s new on-board device electronics.
“During the test work cell build, early in the program, issues with the client’s control board became evident and opportunities to improve their product were discovered,” said Neumann. “It was certainly more advantageous for the OEM to address issues early in the design stage, rather than later.”
Mark Crawford is a full-time freelance business and marketing/communications writer based in Madison, Wis. His clients range from startups to global manufacturing leaders. He also writes a variety of feature articles for regional and national publications and is the author of five books. Contact him at mark.crawford@charter.net.
Speed is a top priority for medical device manufacturers (MDMs). With the trend toward smaller, more complex devices, sometimes built from challenging materials, it becomes harder to maintain reliability and quality. Also, with the Affordable Care Act’s focus on outcome-based reimbursements, healthcare systems are eager to provide monitoring-type care, which is why wearables, drug-delivery devices, and point-of-care devices are on the rise. These types of devices also rely more on electronics and wireless technologies, adding another layer of complexity to the assembly process. As a result of these rapid product developments, vendors are being challenged to stay on top of technology to meet market and consumer demands.
“As medical and combination devices become more complex, including requirements such as electronic integration and combination products, we continue to see more complexity in the solutions for automated work cells,” said Al Neumann, Automated Manufacturing Systems manager for SMC Ltd., a Somerset, Wis.-based contract medical device manufacturer. “This is true for high-volume as well as low-volume products.”
More complexity typically means more parts, smaller parts, more functionality, and wireless machine-to-machine communication. Sensor and vision technologies are often needed to provide real-time data that optimizes the entire production process. This ultimately reduces costs and streamlines production by capturing performance data that is used to maximize production processes, including automation. Real-time data is essential for devising the most productive and efficient automation/assembly system possible.
“We are seeing an increased need for more real-time statistical data pertaining to the processes required for assembly,” said William Mis, vice president of sales for Arthur G. Russell Company, a Bristol, Conn.-based manufacturer of custom assembly systems and high-speed feeding systems for the medical device industry.
For example, he noted, IoT sensor data provide views into operational aspects that were not possible before. A proximity sensor once simply sensed the presence of a part; but now, when equipped with an embedded temperature sensor, it can identify a bad bearing or motor before either can create a maintenance issue.
“Smart sensors on machines is part of the Internet of Things and allows for more big-data opportunities,” Mis added. “With big data, data mining and business intelligence can offer more insight to the plant floor and recognize trends on machines and parts of machines, which improves operational efficiencies and keeps costs down.”
Experienced Partners Wanted
OEMs want to work with contract manufacturers that try to stay ahead of the game by investing in more sophisticated controls systems and improving their assembly and automation technologies to maximize quality, production, validation, and speed to market. They seek a perfect match in mindset and culture—continuous upgrades in automation and assembly equipment, automated real-time process controls, and automated feeding systems. Solutions that offer flexibility and creativity (but still with 100 percent verification and consistent, repeatable cycles) are in high demand. Finally, OEMs want this without having to ask for it—this kind of display of leading-edge knowledge makes them feel confident in moving ahead quickly with a comprehensive proposal that accelerates production.
“OEMs expect automated solutions to reduce risk and improve product performance, without sacrificing product quality,” said Keith Calvert, engineering director for The Tech Group, a Tempe, Ariz.-based contract manufacturer of medical devices. “Speed to market is still the big driver with every OEM today.”
As parts get smaller and products more complex, OEMs count on assemblers and automation providers for design guidance, especially with process development/proof of principle. Top concerns are reliability, precision, and speed. OEMs are reaching out more to contract manufacturers as advisors—not just large automation houses that have proven experience within the medical device sector, but also small equipment vendors and in-house or third-party validation experts for niche applications.
“While the majority of our business is still providing our valves, pumps, and integrated sub-assemblies directly to OEMs, we have seen an increase in our business with contract manufacturers and engineering design firms,” said Craig Occhiato, segment manager for microfluidics for Bürkert Fluid Control Systems, a Charlotte, N.C.-based manufacturer of measurement and control systems for liquids and gases for the medical device industry. “The smaller firms normally buy components and design and build complete systems in-house. Larger and medium size firms, like many OEMs, see the value in outsourcing portions, or the complete fluid handling system, to an experienced firm.”
Calvert agreed.
“Typically, our OEM customers lean toward automated assembly solutions to mitigate risk and improve efficiencies,” he said. “We are seeing a shift toward engaging with contract manufacturers and their assembly partners earlier in the development process as advisors. This helps ensure the assembly solution meets good DFM/DFA principles of repeatability and reproducibility throughout the manufacturing and assembly process.”
More Complexity, More Challenge
Assembly isn’t as easy as it used to be. For example, with the increase in the number of connected devices, there is more integration of electronics assembly, with 100 percent verification of device function. All appropriate locations on the assembly line must be protected from electrostatic discharge (ESD). Work instructions need to be completed and the operators and technicians on the line need to be appropriately trained for ESD protection.
“It is also essential that complex on-line verification tests are developed through proof-of-principle testing, and then integrated into the automation,” stated Meredith Canty, director of drug delivery systems for SMC. “The on-line verification testing then needs to go through extensive validation to ensure it is yielding the correct results.”
Packaging requirements during the assembly process flow must also be taken into account, as there could be multiple layers of packaging that include the primary pack heat-sealed bag, secondary pack custom-corrugate pack with multiple devices, and tertiary packaging—placing the custom corrugate packs into a larger corrugate box. “The placement of devices, literature, labeling, and tamper evidence must be taken into account during the various packaging steps,” she said.
Combination products also present unique challenges. For example, final device assembly equipment is seeing more integration of the primary drug product container and serialization of each device. “Many of the primary drug containers (PDC) are made out of glass and a certain percentage of them break during handling and assembly,” said Canty. This breakage must be considered when designing the automation. The machine should be as robust as possible to prevent breakage, but the automation also needs to be easily accessible for repair if needed, or cleaning if there is breakage. “It is also important to ensure the automation does not break sterility of the PDC—this could happen by moving the rubber stopper or dislodging the needle shield,” she added.
Sometimes implementing well-established standard processes still requires some creative adjustment or modification that is identified through risk mitigation and documented capability studies, in order to deliver a successful proof-of-principle endeavor. These processes are then automated and validated to current U.S. Food and Drug Administration requirements, including 21CFR Part 11 compliance, on the equipment being delivered. For example, assembling combination devices requires a higher degree of precision to avoid glue or silicone residue coming into contact with the drugs.
“With ultrasonic welding, laser welding, or glue bonding, sometimes there are characteristics in a product design that can be detrimental if processes are performed in one order versus the other,” said John Wuschner, vice president of engineering and quality for Kahle Automation, a Morristown, N.J.-based designer and builder of automation systems for medical device companies. “Other situations could be the need for special fixturing to improve reliability, or a small design change to an energy director that can be the difference between part flash/particulate and a clean robust weld.”
Developing an Automated Solution
Like design for manufacturing (DFM), planning for automation during the product design phase is as important as planning for any other segment of the manufacturing process. There are multiple stages of automation, beginning with the manual assembly stage. This knowledge is then applied to the hand-loaded automated assembly equipment (manumation). Manumation equipment can be used for engineering testing, design verification, clinical trials, and commercial launch if validated appropriately. The goal is to take the learnings from the manumation and apply them to a larger-scale assembly line for commercial scale-up. Part loading can still be conducted manually at this stage if needed, but usually, there are bowl feeders and/or tray loaders to handle parts. The final packaging also needs to be considered to determine what type of scale automation is required to keep up with the assembly equipment.
As devices become more complex, contract manufacturers and supply chain vendors work more directly with OEMs to create cost-effective solutions for proof of concept. “It’s a service we have provided for years, but now more OEMs are asking for it,” said Neumann. “This allows OEMs to verify their concept and reduce risk prior to investing in expensive equipment.”
Customers also want cost-effective automation cells that can be built within a short time frame. Products are often modified, or test requirements changed, during work cell builds. “Timelines and budgets often remain the same, so we’ve learned how to improve efficiency while building in a modular, more flexible style,” said Neumann. “Flexible work cells are more capable of adapting to product design revisions or product volumes changes.”
Sometimes for complex products, special adjustments (or even custom-designed equipment) are required to make everything work out. For example, assembling combination devices requires a higher degree of precision to avoid glue or silicone residue coming into contact with the drugs. Kahle Automation has developed higher-accuracy dispensing valves and precision mechanical placement tooling to support these processes, eliminating any splatter from valve shut-off. The new valve opens and closes without affecting the dispensing volume, or generating any minute droplets around the components.
“If specifications require a tight tolerance in glue or silicone quantity, these valves are the only choice to meet that specification,” said Wuschner. “With glue, often the specification is to guarantee acceptable adhesion [on the low side] or avoid cosmetic defects or migration of the glue into an area that is undesirable [on the high side, or with splatter]. Conditions outside this tolerance will lead to waste or possible product performance issues.”
Once a work cell has been designed, advanced sensor technologies can simplify work-cell operations. For example, some sensors can be adjusted using the work cell’s human-machine-interface (HMI). “The HMI can now provide an ergonomically convenient location on the work cell that a technician can use to safely adjust or monitor sometimes hard-to-access sensors,” said Neumann. “When a linked component is replaced, stored values are automatically downloaded to the new device, eliminating possible inputting errors. Also, many sensors look the same, yet may have very different operating characteristics; the control system will alert the technician if a replacement sensor is not exactly the same as the original.”
Injection Molding
Advanced sensor technologies can also enable highly automated injection-molding techniques, where cavity pressure transducers and vision systems are integrated into the process to ensure only high-quality parts go into the automated assembly cell. Also, as plastic medical devices get smaller and more intricate, engineers have fewer options for assembling their components. Although friction-based joining processes such as ultrasonic welding, spin welding, and vibration welding are generally fine for most assemblies, they can also generate particulate contamination, which can be a problem for some devices. Laser welding solves that issue.
“The overriding reason medical device manufacturers choose laser welding is that it’s a clean joining method,” Hugh McNair, manager of laser applications and systems at Branson Ultrasonics Corporation, a provider of laser plastic welding technology based in Danbury, Conn., said in a recent article in Assembly Magazine. Branson utilizes an infrared laser welding process that distributes the energy to the entire joint line simultaneously (in other technologies, the laser traces or scans the joint line progressively). Illuminating the entire bond line simultaneously reduces overall cycle time, enabling the technology to be considered for high-volume assembly of disposable medical devices. Depending on the application, cycle times range from 0.5 to five seconds. “We’ve done applications in as little as six to eight milliseconds per part,” said McNair.
Some medical devices have unique material requirements that affect assembly. For some materials, laser welding works well for bonding parts made from different materials, especially if they are heat-sensitive materials, or the assemblies contain sensitive electronics. For other multi-component products, or for materials that may not have natural adhesion, such as liquid silicone rubber (LSR) and thermoplastics, laser welding is not the best method. In these situations, two-shot injection molding can be used to reduce the number of parts needed for final assembly or the number of secondary steps required.
SIMTEC Silicone Parts LLC, a Miramar, Fla.-based manufacturer that specializes in LSR injection molding, has developed a new technology for manufacturing multi-shot LSR/thermoplastic/metal components. The conventional approach requires two separate tool sets—one for the silicone and another for the thermoplastic. In addition, the metal part would have required assembly with both the silicone and thermoplastic components in a secondary operation. From a cost perspective, this conventional approach requires significant investments not only in tooling, but also in assembly lines and tooling validation at various stages of production.
“Employing state-of-the-art technology, SIMTEC and its sister company, RICO Elastomere Projecting, have developed a multi-shot solution,” said Enrique Camacho, president of SIMTEC Silicone Parts. “Both the thermoplastic and liquid silicone rubber components are injection-molded, using a two-shot manufacturing process. An intermediary process facilitates the presentation of the metal part into the thermoplastic mold for overmolding. This solution enables the integration of functions and materials in a controlled environment, which in turn allows for the elimination of assembly lines while also ensuring part cleanliness and a zero-PPM rate.”
Vision-Based Inspection
Vision-based inspection systems are a must for maintaining quality and manufacturing standards. These systems can evaluate parts or products from almost any point of view or orientation. High-resolution photos can be compared to the actual geometry in imported CAD files. Visual coordinate measuring machines are also used to rapidly measure complex shapes—up to 80 or more contours can be measured in one minute or less. Parts can be inspected at any time during the production process—as a final product, or in-situ inspection as they are being produced, in real time, eliminating the need for offline inspection.
Most vision systems provide high-speed, high-definition inspection from multiple angles at the micron level, through adaptable vision sensors. Easy-to-use graphic user interfaces are operated via a touch screen. The system stores and records high-definition images and data for every product examined, allowing for real-time statistical process control, which can be used to significantly reduce future engineering and build costs.
Typical applications for machine vision systems are robot guidance, motion control part orientation, dimensional inspection pattern and/or character recognition, 2D and 3D barcode reading, label inspection, printing inspection, and quality control. For automation and assembly, this includes critical assembly steps such as height checks, flow tests, load tests, weight checks, etc. Sometimes off-the-shelf systems will work, but with increasingly complex products, some MDMs partner with vendors to create custom systems for their needs, or the automation vendor builds its own proprietary system in-house.
For example, Kahle Automation has recently developed a novel glass-defect vision inspection system for identifying printing defects, cracks, nicks, and particulate matter that inspects 360 degrees of a glass tube (one-degree resolution) at a rate of 240 parts per minute, and can be scaled for higher production. “By inspecting the glass prior to assembly, we avoid adding value to product that will ultimately become scrap,” said Wuschner. “This saves the customer money and keeps the line running at a higher efficiency.”
Moving Forward
It is often assumed that automation is only for high-volume needs. This is not the case. Automation also benefits low-volume programs by ensuring repeatability, eliminating human error, and providing 100 percent verification of each device. Automated assembly aids and testers can often be justified for low-volume needs when there is a high device value, or when test results during assembly are critical. “Many programs start out as low volume before the product line is established,” said Neumann. “This is a perfect time to implement ‘bridge’ work cells that offer more positive assemblies than purely manual operations, and allow us to plan for the more complex automated cells, which will be incorporated later.”
Electronic components, and vision hardware and software, are constantly improving. To stay on top of technology advances, forward-thinking companies continue to bring creativity and innovation into the next-generation platforms they create. For example, Bürkert has built in-house, value-add capabilities (valve/pump/sensor/manifold assemblies) tailored to its customers’ needs. These custom systems are often the basis for the company’s next-generation standard/off-the-shelf products and technologies.
“Our pneumatically driven pump/dosing systems are a good example,” said Occhiato. “Positive displacement dosing at volumes from 50 uL to 1,500 uL per dose [1-2 percent accuracy] are standard options for cleanable units or single use. While the technology is not new, the design and the manufacturing can be a challenge, draining time and resources. Our standardized modules and experienced team offers our customers this alternative dosing technology to consider that offers many benefits over traditional methods.”
Many process problems can be mitigated through the use of small design changes, without affecting the functionality of the product. “The key is to involve the prospective automation vendor early in the design process, where principles can be proven and hypotheses of improvements can be tested before the choices become costlier,” said Wuschner. “For example, a simple chamfer on a mating component can be the difference between an easy assembly and a difficult one. Also, symmetry of components that enable multiple orientations allow for more possibilities for first-time success.”
Neumann agreed that early involvement between the OEM and the assembler/automation vendor is crucial. A recent complex tester, he noted, was designed and built at SMC and required communication with the customer’s new on-board device electronics.
“During the test work cell build, early in the program, issues with the client’s control board became evident and opportunities to improve their product were discovered,” said Neumann. “It was certainly more advantageous for the OEM to address issues early in the design stage, rather than later.”
Mark Crawford is a full-time freelance business and marketing/communications writer based in Madison, Wis. His clients range from startups to global manufacturing leaders. He also writes a variety of feature articles for regional and national publications and is the author of five books. Contact him at mark.crawford@charter.net.