In the fast-paced world of industrial coding and marking, clear and durable labelling is crucial for everything from food packaging to shipping logistics. When it comes to industrial coding and marking, there are different methods to print variable information on products and packaging. One standout technology in this arena is Thermal Transfer Printing. In this article we will look into the specific qualities and benefits of printing with thermal transfer ribbons, its applications and how thermal transfer ribbons play a vital role in this well-known printing method.
Exploring different industrial coding & marking solutions
Before we look more in-depth at Thermal Transfer Printing, it’s important to understand the various coding and marking technologies available in the industry. Each method has unique advantages suited for specific applications.
Inline industrial coding:
A lot of the industrial coding is done “in-line”, meaning that the printer is integrated into the production line. There are 3 main techniques for this type of industrial coding & marking:
- Thermal Transfer Overprint (TTO)
Thermal Transfer is a method where heat is used to transfer ink from a Thermal Transfer Ribbon onto a substrate. The inline Thermal Transfer technique for industrial coding is called Thermal Transfer Overprint or TTO and it is very suitable for printing on flexible packaging materials.
- Inkjet print
Coding with inkjet printers creates characters onto the receiver materials by spraying droplets of ink through a print-head that shapes the print through electrical pulses.
- Laser marking
Laser marking is a method where a beam of concentrated light is used to create a lasting mark on a surface. This method does not use ink but makes the information visible through discoloration of the receiver material.
Each of the above techniques have their specific qualities. Industrial coding printers that work with Thermal Transfer have the smallest footprint and require the lowest investment. In addition to this, the printers are working with relatively simple technology, making them robust and reliable.
Thermal Transfer is often chosen for durability reasons as it is able to create prints that are resistant to many different circumstances such as abrasion and chemical exposure. Thermal Transfer also offers the widest range of printable substrates.
Offline industrial coding
In addition to inline printing, some of the labelling is also done on stand-alone printers, where the label is first printed and applied to the final product in another step, either manually or automatically. This type of industrial coding can also be done through different techniques.
- Thermal Transfer
Thermal Transfer is a method where heat is used to transfer ink from a Thermal Transfer Ribbon onto a substrate. For stand-alone printers, two different types of prin-theads are available, near-edge and flat-head. The choice for the type of print-head depends on the requirements such as print-speed, durability of the print etc.
- Direct Thermal
Direct Thermal is a method where heat is used to create an image by discoloration of a special receiver material. These substrates have had a chemical treatment that make them change colour upon exposure to the print-head.
- Laser printing
Later printers work through the application of toner ink that is shaped on a printer drum through static electricity, after which the drum is rolled over the substrate to shape the final image.
Choosing the right technology depends on your specific requirements, such as the type of material, print volume, and environmental conditions.
Why Opt for Thermal Transfer Printing?
While other printing methods like inkjet and laser marking have their own benefits, Thermal Transfer Printing excels in quality and durability. Below are a few reasons to choose Thermal Transfer Printing for your industrial coding and marking needs:
- Exceptional print quality: TTR prints deliver crisp, clear images and text that can withstand wear and tear, making it ideal for labelling products.
- Versatility: This method works on various materials, including paper, plastic, and metal, making it suitable for a wide range of applications.
- Cost-effective solution: Thermal transfer printing is efficient for medium to high-volume printing, allowing businesses to save money in the long run.
- Durability: Prints created with Thermal Transfer Ribbons are resistant to moisture and chemicals, ensuring they remain legible even in demanding environments.
Thermal Transfer on an industrial coding printer with flat-head print-head
Industrial coding machines with traditional flat-head print-heads can generally provide image resolutions between 200 and 600 dots per inch (DPI), in some cases, this can go up to 1200 DPI. Their ribbons are combined with labels for a small distance to the peel point after passing the heating element. These print-heads will commonly print at speeds up to 12 inches per second (IPS). Some printers are able to print up to 20 IPS when the right ribbon is selected.
Due to the design, flat-head printheads are able to provide the print with the highest durability on the widest range of substrates. Thanks to the relatively long exposure to the print-head, the ink transferred can be strongly adhered to the surface of the substrate by activating specific components in the ink formulation.
Thermal transfer on an industrial coding printer with near-edge print-head
Industrial coding machines with floating near-edge print-heads will run more than twice as fast as their flat-head equivalents. Speeds over 26 IPS are the norm, where 55 IPS is also reached by certain printer-ribbon combinations. Ribbons for near-edge printers are combined with labels only for an instant prior to the peel point, requiring a special formulation engineered for quick release of ink from the base PET film. A floating print-head means not having to make adjustments for various media thicknesses. In addition, the image resolution for these printers is between 200 to 300 DPI.
Thermal transfer ribbons for industrial coding
Thermal transfer ribbons are made in 3 main formulation groups. For industrial coding, we look at the formulations as follows:
- Wax-resin: Wax-resin ribbons are the most common starting point for industrial coding & marking, especially for in-line TTO/printing.
- Resin: A resin formulation should be considered in case of specific durability requirements.
- Wax: Waxes can be used for logistical prints such as box labels etc. These formulations are not used in in-line/TTO printers.
The different types of print-heads require different ribbons. The main difference between a flat-head and a near-edge ribbon is the release layer. This is a specific component between the carrier film and the ink layer that ensures the ink is released onto the substrate properly. High print speeds, especially when it comes to in-line/TTO printers, require an extremely fast release of the ink as it passes the print-head.
When you are looking for high durability and are therefore shopping for a resin ribbon, it is good to understand what makes printing with a resin ribbon so durable. It starts with the resin component in the ink, which creates a strong resistance against chemicals, abrasion, sunlight etc. In addition to this, resin ribbons can be formulated with an extra adhesive layer on the surface of the ink layer. This layer creates a strong adhesion between the surface of the substrate and the ink, resulting in an even more resistant print.
Dust is present in many industrial environments and it is important to mitigate possible printing problems by choosing high quality thermal transfer ribbons. The movement of the ribbon past the print-head can create static electricity in the printer, drawing dust into the printer which can affect both the quality of the print and the life of the printhead. Good quality thermal transfer ribbons have a special layer to prevent the build-up of static electricity in the printer, resulting in optimal print results and printhead life.
Applications of Thermal Transfer Printing
The variable information applied during industrial coding & marking can come in the form of barcodes, QR-codes, batch numbers, expiration dates and other crucial data. As this information is often critical with regards to traceability, compliance and product safety, correct printing methods need to be in place to ensure that readability, scannability and longevity meets the requirements.
Thermal Transfer Printing is widely used across numerous industries, including:
- Food & beverage: Printing expiration dates and barcodes on packaging for consumer health & safety.
- Pharmaceuticals: Printing of serial numbers, batch numbers and other crucial information meeting strict regulatory requirements.
- Electronics: Marking components and circuit boards with essential information.
- Shipping & logistics: Creating shipping labels and tracking codes for packages.
The exact requirements of the print depend very much on the application. One important factor in choosing the best Thermal Transfer Ribbon is resistance to the content of the packaging. Examples of this are food items (e.g. fats and oils) and products like detergents (cleaning chemicals). Such application requirements also demand resistance against these products and ingredients.
Another factor that may influence the choice of TTR, in case of Thermal Transfer Printing, is the expected external exposure, such as humidity, temperature and chemicals like cleaning alcohol. The last can be a very important requirement for pharmaceutical items and medication, where cleaning alcohol is prominently present in the environment which the print is exposed to.
The required lifetime of the print also needs to be taken into consideration. In many cases, the variable information should outlast the shelf-life of the product itself with a considerable amount of time to meet legal requirements.
Substrates for industrial coding printers
Industrial coding printers can be used to print on a wide range of materials, ranging from uncoated papers to high-end synthetics.
The chosen substrate, in combination with the Thermal Transfer Ribbon determines the durability of the print. In case certain exposures, such as chemical agents, sunlight or abrasion, are expected, this needs to be reflected in the choice of materials. Another important factor to consider is the need for certain certifications, such as UL and Isega.
After selecting the substrate, the next crucial step to achieve optimal print quality is pairing it with the appropriate thermal transfer ribbon (TTR). The label’s surface texture plays a significant role in this match; rough substrates like uncoated paper and Tyvek® require different ribbons than smoother materials like PET and vinyl.
For rough surfaces, the challenge lies in retaining ink on the top, as failure to do so can lead to unreadable grey prints; wax in the ribbon helps mitigate this by melting into the roughness while preserving ink visibility. Typically, ribbons for such labels are made from wax or wax-resin. Though some manufacturers have developed resin ribbons suitable for these surfaces.
In contrast, very smooth surfaces require a different strategy, as ink can easily smear. Here, an adhesive incorporated into specific thermal transfer formulations is essential to secure the ink to the substrate through the right heat application.
Consulting high-quality suppliers of TTRs, labels, and printers can guide you in identifying the best options for your needs.
Harmonising printer, label and ribbon
When considering various production environments and durability requirements, choosing the ribbon, substrate, and industrial coding machine is just the initial phase of the selection process.
After finalising these components, it’s crucial to conduct testing and identify the optimal settings that synchronise them effectively. The printer must be adjusted for the right temperature, speed, and pressure according to the substrate and ribbon combination.
- Proper heat settings are essential for ink release and image quality, with wax ribbons needing lower temperatures and durable resins requiring higher ones.
- Print speed significantly affects the outcome and must be balanced with temperature and pressure. Excessively low temperatures or high speeds can result in faded prints, while too high temperatures or low speeds can create overly thick images.
- Adjusting print-head pressure offers further customisation options for achieving the desired results. With the correct settings in place, industrial label printing can ensure variable print excellence and smooth operational workflows.
In conclusion
In conclusion, the selection of thermal transfer ribbons and printing techniques in industrial coding and marking is pivotal for ensuring product traceability, compliance, and safety. The ability of thermal transfer systems to produce durable prints on a variety of substrates positions them as a preferred choice, especially when environmental exposures and longevity are crucial. Various industrial applications and environmental conditions dictate the appropriate combination of printer, ribbon, and substrate, requiring careful consideration and testing. Ultimately, harmonising these elements results in optimal print quality and efficiency, supporting manufacturers in adhering to regulatory requirements and maintaining high standards in product labelling.
