By Liz Stevens, writer, Plastics Decorating
The medical products market is a growing and ever-evolving market sector. With this growth, there continues to be opportunities for plastics molding as well as decorating of medical devices. Catering to this market, however, calls for flexibility and pinpoint accuracy in the manufacturing and decorating processes. This accuracy must be repeatable for job after job and batch after batch.
Pad printing offers features that make it a natural fit for use on medical products. Pad printing is known for its ability to deliver markings with extreme accuracy and clarity on hard-to-print objects. Inks used for pad printing on medical devices are available to meet the high standards for this industry. This printing technique is reliable, and its supply chain for equipment and supplies is mature and sophisticated. Plastics Decorating spoke with a handful of pad printing experts who understand the special needs for pad printing on medical devices.
The experts are Micah Swett, sales manager at Diversified Printing Solutions, Charlotte, North Carolina, which offers printing equipment supplies and automation solutions; Richard Ingram, technical service manager for screen and pad printing inks, Marabu North America, LP, North Charleston, South Carolina, a manufacturer of specialized inks for over 150 years; Brian Bishop, founder/CEO, Automark, Katy, Texas, a pad printing equipment and supplies distributor, featuring Tampo Techniek Nederlands equipment; Keith Ekenseair, president, Pad Printing Technology, Bradenton, Florida, a provider of printing services, including pad printing and a specialization in medical manufacturing; and Attly Aycock, CEO at Remington Medical, Alpharetta, Georgia, which designs, manufactures and distributes disposable medical devices.
Pad Printing Advantages
The printing and labeling of medical products are characterized by the need to work with products of all sizes and products that come in a vast variety of shapes. In all cases, it is imperative to apply clear, accurate markings that have exceptional durability. Pad printing steps up to these requirements with advantages that make this printing technique a winning choice.
Swett explained the drawbacks of other techniques and laid out pad printing’s edge. “Using labels for these types of markings is problematic because it is difficult to change the data on labels, and with the fast pace in the world of medical products, using this method can be quite expensive.” Swett noted that another downside of using labels is that, as a material that is separate from the product, labels can become contaminated – and any contamination makes them unusable. “On the other hand,” said Swett, “pad printing can be compatible with sterilization and disinfection. Pad printing excels in precision, even with complex/curved and irregular/ergonomically shaped parts, a common feature of medical devices. A wide assortment of inks is available for the many types of materials used in medical devices.”
Ingram pointed out the consistency and reliability of pad printing. “An advantage that pad printing has over other printing and label processes stems from its repeatability,” said Ingram. “With pad printing, everything about the job is measurable and repeatable. That, for Marabu, is the biggest advantage. The materials in medical products vary widely and the products themselves really run the gamut.” Ingram explained that even medical products of a similar shape have differences. “For instance,” said Ingram, “there are very thin tubes and very fat tubes and other tube-like products such as syringes. With each of these, it takes precision to print on the object, and one must be able to measure the ink volume to be used on each print, and then be able to deliver this same marking repeatedly. That is where pad printing rates higher than anything else.”
For Bishop, pad printing’s advantages are many. “The main advantages of pad printing are speed, durability, precision and having the ability to use inks that are compatible with the material requirements,” he said. “For example, many items have biocompatibility requirements and many inks are designed to meet those strict requirements and have passed testing by a regulatory authority. Some products, like syringes and catheters, require extreme precision and pad printing can maintain the precision without sacrificing speed in labeling.” Bishop identified that speed can be interpreted as not only the rate of output of a product but also the time it takes to switch between jobs to print different products.
Ekenseair said that, for him, “pad printing allows for higher quality and better tolerance control for medical devices than other forms of printing.” Aycock cited several advantages. “The cost of materials is low for pad printing,” he said. “It is great for prototyping; it is easy to make changes with pad printing and the print plates are fairly inexpensive.” He noted that labels aren’t well-suited for products that need to be sterilized or regularly cleaned and that there is extra cost for labels on single use disposables. “The downsides with inkjet printing,” said Aycock, “are that it requires a larger capital investment for equipment, and it is slower. With pad printing, on the other hand, one can apply a single color quickly, the drying time is minimal, and the marking can be treated to be resistant to wear.”
Ink Standards
For medical products, in addition to being durable and biocompatible, the inks used must meet high federal and international standards as well as receiving USP certification. The inks must have the highest durability so that, for instance, products that include measurement marks remain legible and accurate for the long term. Some medical products have to be biocompatible and completely adhere to the product so that no ink particles can slough off.
Ekenseair provided some details. “Generally, for medical devices, the ink will only need to be medical grade if it comes into human contact,” he explained, “whereby they are subject to concerns regarding skin irritation, toxicity or biocompatibility concerns. For devices presenting toxicity and/or biocompatibility concerns, inks that meet the medical specifications of the US Pharmacopeial Convention Class VI are typically used.”
Ingram described some of the medical device printing requirements. “When printing for medical devices, the markings could be on a single-use solution syringe which doesn’t go anywhere near a patient’s body; the solution is just pumped and the syringe then is thrown away,” he said. “But with catheters and other devices that actually do go into the body, there is a much higher standard.”
Bishop detailed some of the standards and requirements. “There are standards for ink based on the type of device being printed on,” he said. “The regulatory body that tests biocompatibility for plastics, for example, is the United States Pharmacopoeia (USP). This independent body set standards for the exposure of plastics to human tissue ranging in six classes, where Class VI has the most stringent safety standards set based on three testing standards. These testing standards are based on implantation tests, systemic toxicity tests and intracutaneous tests.”
Aycock added more context and noted additional guidelines that may be applicable. “There are at least three requirements that must be met,” he said. “For biocompatibility, the ink should not cause adverse reactions if it comes into contact with a patient’s body. Based on the use of the medical device (such as skin contact only, or subcutaneous use), it must meet various portions of ISO 10993. Material compatibility is another requirement: the ink should not compromise the device’s safety or performance. Cleanliness and sterilization requirements call for the ink not to interfere with sterilization procedures. If the medical device is reusable, the ink must be readable for the life of the device.”
Cleanrooms
Pad printing for medical devices sometimes requires the use of a cleanroom to ensure the highest level of cleanliness and sterilization.
Ingram contrasted the use of cleanrooms in the US and surrounding areas to the concern shown (or not shown) elsewhere. “While pad printing for medical devices in other parts of the world often has lax standards for cleanliness,” said Ingram, “in the North and Central American market there is much greater focus on keeping the production environment as clean as possible. These products are used in highly sensitive medical situations, possibly for surgeries as critical as heart transplants. It sounds overblown but a particle of dust on a medical tube could possibly mean life or death for the patient.” Ingram stated that medical industry manufacturers have to show their customers that they are doing as much as they possibly can to keep everything clean, precise and contamination-free.
Bishop offered insight from the equipment manufacturer’s viewpoint. “Medical devices are separated into three classes,” he explained, “where Class 1 is the most common and includes items like toothbrushes and stethoscopes. Some of these items are not printed in a cleanroom but are sterilized and packed in cleanroom environments.” Most medical application equipment is used for Class 2 products, such as catheters and syringes which are pad printed in a cleanroom environment. “Class 3 products,” said Bishop, “are the highest risk parts – like ventilators and pacemakers – which require cleanroom manufacturing processes although they represent the smallest volume of medical devices approved annually by the FDA.”
Ekenseair described what is common among pad printing technology customers. “The customer generally will make the decision whether to have their components pad printed in a cleanroom environment,” he said. “After pad printing and assembly, medical devices often will go through some type of sterilization process and so pad printing in a cleanroom environment is not required. About 50% of our products are printed in our Class 8 cleanroom.” And Aycock added another perspective. “A cleanroom or clean environment is not always necessary for pad printing, but particulates often need to be kept to a minimum for the device being printed on. Cleanliness is less of a concern if the device is non-sterile or if foreign bodies/contaminates/bioburden agents present would not be introduced to a patient during use of the device.” He noted that other printing technologies may actually introduce more contaminants into the air, making them less suitable to use on medical devices that need to be made in a cleanroom.
Safety
In addition to standards for ink and cleanrooms for production, there are safety reasons that make pad printing a standout for medical devices. The importance of safety can be seen in a variety of areas of production.
Swett cited safety as it applies to the ink supply. “The closed ink cups used for pad printing have less exposure to chemicals; a very thin ink film bonds to the part, precluding contamination or damage to the parts being marked.” To Ingram, safety means production control and repeatability, including quality control. “Quality control starts with us, particularly within our operation in Germany that puts the inks together,” Ingram explained. “They have a strict tolerance there; if the ink is out of tolerance there, it comes down the system in that condition to the customer, who has their own strict safety regime of quality control. It does start with us because we are the ones that are going to produce the ink.”
“The safety reasons are numerous,” according to Bishop. “This includes the accuracy of printing to ensure that doses are consistent, the ability to mark items for traceability and the ability to mark parts without altering the substrate. These are all reasons to consider pad printing as an excellent way to mark parts. Traceability of the inks and ensuring that the inks have been tested for biocompatibility, are other reasons to use pad printing. Finally, with the very consistent process in pad printing, the ability to print in cleanrooms and the capability to print very small, detailed images allow companies to be confident that they are offering the end user a way to mark products in the safest way possible.”
Ekenseair stated that “pad printing allows for image marking on medical devices that does not affect the product’s intended use and does not hinder the ability to pass strict safety testing.” Aycock reiterated and expanded upon the safety concerns. “The inks used by Remington are tested for biocompatibility which confirms that the inks will not adversely impact patients or caregivers during use,” he said. “Many pad printing inks use a carrier that evaporates after the ink is applied. Some of the inks have carriers that are hazardous, so we as manufacturers have to store and handle them very carefully.”
Automation
A manufacturing operation that demands accuracy, precision and long-term repeatability is an excellent candidate for automation – such as vision systems and robotics – that can help to standardize production and ensure those crucial qualities. We asked if robotics and automation are playing a role in the growth of pad printing and medical manufacturing.
“Absolutely,” said Swett. “we have advanced with the industry in the use of automation and robotics in medical manufacturing, using less human interface with automatically fed systems, and vision inspection for quality control has really improved pad printing for medical and in many other industries.”
“Automation and robotics are playing a massive part now,” said Ingram. “Robotics has changed dramatically since its start, and the costs have dropped. Pad printing manufacturers now are offering automation and many of our distribution partners that manufacture pad machines offer turnkey solutions which almost are entirely hands-off.” Ingram noted that laser and video identification automation can identify bad parts or poorly printed parts, and sensors can scrutinize the printed areas to see, for example, if too many microns of ink were applied. “Automation also is being used in the corona and plasma pre-treatment of medical devices.”
“Delivering this technology as a standard out of the box,” Bishop explained, “allows companies to purchase machinery now and potentially implement robotic triggering in the future. Another option is to custom design printing machinery to fully encapsulate the loading, pre-treating, printing, drying, unloading and even packaging of parts. Addressing the entire printing process allows companies to focus on building parts and ensures the highest output, lowest reject rate and highest quality.”
“Automation and robotics play a key role in pad printing for medical devices whereby the quantities being printed justify the cost of automation and robotics,” said Ekenseair. “Products with volumes in excess of 1.5 million generally are considered good candidates for consideration of automation. Lower volumes, however, generally will not justify the additional cost.”
Aycock expanded on how production volume affects the decision to automate or not. “Remington Medical does not pad print in high volumes,” he said, “so our need for robotics and automation is limited. The newest pad printer that we purchased does have some basic automation features. These features have helped with registration of multiple colors and have sped up the printing process. And inspection technology has improved in recent decades in ways that facilitate higher volume/faster production by using automation.”
New Applications
Pad printing has earned a reputation for offering production speed, for being versatile and flexible and for being cost effective. New medical applications have opened doors for new business opportunities. “I have seen pad printing being used to print on components of larger devices than historically were historically thought of as possible to pad print, for example with imaging machines,” said Ekenseair. Swett has seen an uptick in radial prints on syringe and tubular shaped objects (likely for lower and medium volume runs).
Ingram pointed to the capability to print on the tiniest of objects. “Some of the devices being printed on are incredibly small and thin,” he said. “And you have to have a certain amount of ink at a certain viscosity, formulated to a certain standard, and then applied to a certain line on tubes, for example, that are super thin.” Ingram cited automation as the development that has allowed this level of precision. “The way things are going with the medical industry, everything is evolving. There is a big push for all the weird and the wonderful, and for keeping everything as clean and as safe as possible.”
“We continue to see new applications for pad printing within our business,” said Aycock, “particularly in printing on machined metals and molded components. This led to our purchase of an additional pad printer within the last year. In my opinion, the continued use and growth of pad printing is related to the relatively low start-up cost of pad printing and the relative ease of the manufacturing process, particularly with newer equipment.”
Bishop also sees new opportunities arising. “Pad printing continues to grow with the medical market,” he said. “We see everything from pills to catheter tubes being printed with pad printers. The pad printing industry continues to push the boundaries as machines are designed and built to meet the stringent protocols of cleanroom compliance and to assist in fully automating the printing process to ensure even better accuracy and eliminate human error. As demand continues to grow, these processes will be pushed for higher output which hopefully will lower rejection rates and improve medical companies’ ability to get products into the marketplace at lower prices with greater speed.”
For more information, visit www.diverprint.com, www.marabu-northamerica.com, www.automarkco.com, www.pad-printing.com and www.remmed.com.
