Originally Published MPMN July/August 2005
Not Just Scratching the Surface Anymore
Manufacturers offer new alternatives in laser coding, thermal printing, and surface treating
Options available to manufacturers for printing and marking on medical devices continue to expand. Thermal printing for labels and packaging can produce two-dimensional bar codes, as well as special characters. The permanent nature of laser coding and marking may prove to thwart possible counterfeiting of parts and goods used in the manufacture of medical devices.
Thermal Printers Are Compact, Versatile
The Thermal Printmaster from About Packaging Robotics (Thornton, CO) can be used on pouches, bags, lidding stock, and preprinted media. Its 300-dpi resolution with near-edge printing capability gives the appearance of preprinted pouches and its flexibility enables on-demand production of text, graphics, and bar codes. Suitable for use with Tyvek and other flexible packaging materials, the unit can print directly on media ranging from 1.5 to 10 in. wide, with a maximum print area width of 8 1/2 in. Media printing and processing rates range from 4 to 10 in./sec. The printer features a rugged steel printing platform and a stepper motor–driven infeed.
|A printer from Fujitsu Components America Inc. can output data, graphics, and 2-D bar codes.|
A high-capacity thermal printer assembly has been enhanced with more standard features and print capabilities for expanded use in medical and scientific equipment. The FTP-639USL001/002 compact printer unit from Fujitsu Components America Inc. (Sunnyvale, CA) measures 136 × 163 × 107 mm and can print at 200 mm/sec. It comes with an integrated 3-in. thermal print mechanism, an automatic guillotine-type cutter, and either a miniature high-speed serial or USB controller board. Capable of outputting data, graphics, and text characters, the printer can produce 2-D bar codes at speeds of 200 mm/sec with 8-line/mm resolution. The print speed can be decreased to 125, 80, or 40 mm/sec to conserve power. The printer accommodates paper or label stocks ranging from 60 to 120 µm thick and 80 mm wide. Designed to accommodate various mounting schemes, the printer features a partial tilt function. The die-cast metal frame provides durability and mounting stability, as well as ESD protection and heat dissipation or retention.
Laser Coding and Marking Systems Offer Flexibility and Permanence
Laser marking systems are an option for manufacturers looking for printing methods that are durable and cost-effective. The Focus S60 laser coding system from Videojet Technologies Inc. (Wood Dale, IL) can deliver permanent codes on a variety of materials, such as paperboard packaging, plastics, glass, labels, clay-coat, and secondary packaging. Suited for use in high-speed environments, the system provides high-quality print resolution for nearly 100% verification system read rates. Its CO2 laser–based technology ensures clean, low-maintenance operation and eliminates consumable fluids and parts associated with other printing techniques. To meet the needs of nearly any coding requirement, the system can print mixed fonts, logos, special characters, RSS/composite bar codes, and 2-D symbols. An optional graphical user interface offers an intuitive color touch screen with a WYSIWYG display. For applications that require 21 CFR Part 11 compliance, the Focus S60’s software provides built-in, password-protected audit trails of all actions.
|A laser coding system from Videojet Technologies Inc. was used to permanently mark the medical device shown here.|
Baublys Control Laser (Orlando, FL) has introduced a fiber-pumped 20-W laser marker. The ProWriter F20 laser marker uses an active fiber and patented pumping technique that allows the use of telecom-grade diodes with a projected life expectancy in excess of 100,000 hours of operation. With its high-beam energy density, the laser is capable of marking a variety of stainless steels, titanium, alloys, and other materials. Operating on typical house current, the marker does not require special electrical connections or external cooling. Its compact design allows for quick relocation and easy integration into crowded production lines, making it appropriate for industrial marking applications where space is limited.
Surface Modification Has Its Benefits When Printing on Plastic
In order to decorate or print on plastic parts, manufacturers may need to pretreat the products’ surface to ensure adhesion and durability. Julian Joffe, president of Pad Print Machinery of Vermont (Manchester Village, VT), has several insights on the pretreatment process.
“Substrates such as polypropylene and polyethylene may need to be modified to ensure a good bond for ink,” he says. “These extremely inert materials have a very low surface tension and, now that they need to be decorated or marked, their inert nature provides a challenge.
“Pretreatments modify the bonds of the substrate surface and increase the surface energy, allowing the ink to bond to the substrate,” Joffe states. By adding oxygen molecules to the surface, ionic positions are opened so that chemical bonding can occur.
Pretreated surfaces slowly lose their ionic character over time. Because the ionic charges on the pretreated surface dissipate quickly, Joffe recommends incorporating pretreatment devices on the actual printing equipment. “Pretreatment incorporation not only assures you of a good, highly durable ink bond, it also eliminates double handling, thus saving time and manufacturing costs,” he adds.
Joffe offers a simple test to check materials for insufficient pretreatment. “Trickle water over the substrate and watch what happens. The water will either flatten out onto the surface or form small beads that appear to be suspended over the top of the surface. A well-treated surface becomes ‘wet’ when the water hits it and will begin to dry after 10 seconds or longer.”
This test measures what is referred to as the Dyne level—the angle of the side of the water droplet on a substrate surface. “Both polypropylene and polyethylene usually have a dyne level below 35 when they’re produced. For proper bonding, the dyne level must be increased to 42 or above,” says Joffe.
The type of surface treatment chosen by manufacturers will depend on the characteristics of the substrate. Highly curved or shaped parts can benefit from flaming, which energizes the surface to a point acceptable for bonding by using the oxygen present in an open flame. Corona or plasma treatment uses electrical current to create an ozone layer at the substrate surface. “This method energizes the surface while increasing the Dyne level for good ink bonding. It’s the best method for pretreating sheet-fed material,” Joffe says. Chemical wipes can also be used to pretreat surfaces.
Biocompatible Surface Coating Is Wear- and Corrosion-Resistant
|The fiber-pumped laser marker from Baublys Control Laser can operate on typical house current.|
A biologically compatible, wear-resistant coating is suitable for use with softer substrates. Armoloy of Connecticut Inc. (Bristol, CT) developed BIO-TDC, the biocompatible surface coating, for use with medical, surgical, and diagnostic devices. A thin uniform deposit has a nonreflective finish and can be applied to most metals that are used in communicating and noncommunicating devices. The BIO-TDC coating is also suitable for pharmaceutical-handling machinery. The coating can withstand repeated autoclaving and is designed to reduce friction and eliminate galling. The corrosion-resistant coating can be applied at low temperatures to avoid distorting tolerances. The coating has passed rigorous tests for cytotoxicity, systemic toxicity, intracutaneous irritation, implantation, sensitization, hemolysis human blood–direct contact, and material-mediated pyrogenicity.