Thermal Printing Overview
Thermal printing is a digital printing technology where a thermal printhead uses heat to apply a mark or print to a surface. There are two different thermal printing methods: thermal direct and thermal transfer.
Thermal Technology
Thermal Direct
Thermal Direct printing is a digital printing process which produces a printed image by selectively heating special thermal paper as it passes over the thermal print head. The coating turns black in the areas where it is heated, producing the intended text or image. Thermal direct technology is most appropriate when the label's life is short or the product is stored at low temperatures and away from direct sunlight, making it a popular choice in the freight and logistics industry.
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Thermal Technology
Thermal Transfer
Thermal Transfer technology uses a heat-sensitive carbon ribbon, rather than heat-sensitive paper, but still utilizes a thermal print head. The ribbon is melted on to the label which forms the text or image on the surface. Thermal Transfer labels are often tougher in nature, making them less likely to scratch or fade. If the label is intended to last a longer length of time; be exposed to higher temperatures, direct sunlight or rougher conditions like rubbing or scuffing during transit; then Thermal Transfer technology is what you need.
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Wax Ribbons
Wax ribbons are suitable for general purpose printing on paper stocks, making it ideal carton labellingapplications. The high ratio of wax in the formulation means these ribbons have a lower melt point, so a lower heat setting can be used on the printer and high print speeds are achievable. Wax ribbons are the most economical ribbon.
Wax/Resin Ribbons
Wax/Resin ribbons provide a finer image on very smooth, coated and gloss paper labels and some synthetic stocks (e.g. polypropylene, polyethylene, polyolefin). The printed image is more durable than wax, ensuring excellent resistance to scuffing or rubbing which can be a common problem for freight.
Full Resin Ribbons
Full resin ribbons provide excellent performance in harsh conditions including high temperatures, corrosive or UV applications. They are suitable for synthetic and specialty label stocks.
Thermal Ribbon rolls are available with the carbon-side (ink side) facing in or carbon facing out. Different printer makes and models will specify which style of ribbon they require. Also, the roll length of the ribbon needs to match the printer model.
It is important to match the appropriate ribbon to the label material and also ensure correct label printer settings for best results.
Label Material Considerations
ADHESIVE
Acrylic or Hot Melt adhesives are commonly used. Factors affecting adhesive choice are temperature (both at the time of application and for the service life of the label), the nature of the product's surface, and other conditions likely to occur within the supply chain environment. Adhesives react differently depending on the surface energy of the product, for example carton vs glass vs different types of plastic.
DIE CUTTING
A die or dies are used to cut the shape of the label. Rectangles, squares, circles, special shapes, perforations, undercuts (die cuts in label liner) are all options available to suit the application. This is a vital part of the manufacturing process as exact pressure is required for clean cutting, while not cutting too deep, causing die strike, and compromising the integrity of the liner.
FINISHED FORMAT
For thermal printing applications, labels can be supplied on rolls, fan-folded into bundles or even supplied as continuous stock.
Rolls
Rolls of labels are supplied wound around cores. Both the inner diameter of the core and the outer diameter of the finished roll of labels may need to be defined based on the model of thermal printer. The number of labels on a roll will impact the outer diameter of the finished roll. When label volumes necessitate an auto print and apply the solution, labels can be supplied on high capacity (jumbo) rolls to accommodate production volumes.
Fanfold
Fanfold refers to those labels supplied in stacks with alternating folds as opposed to being supplied on cores. This format suits the batch printing of labels self-stack into a neat, manageable bundle during the printing process, offering an easy and convenient solution when affixing labels by hand around the warehouse. Fanfold labels are also used when printing very large batches of labels to minimise the frequency of roll changes.
Continuous or Tagstock
Continuous or Tag stock is non-adhesive and provides an alternate form of visual communication to adhesive labels. Manufactured from cardstock or a range of synthetic stocks, these materials are suitable for thermal printing and use a printed mark on the back of the tag or a 'horse-shoe' notch cut from the side of the tag, allowing the thermal printer's sensor to recognise individual tags.
Sheet Format
Sheet format refers to labels that are cut so that each label or 'label-set' is on an individual sheet, and are often used when the labels are over-printed by a laser printer, rather than a thermal printer.
Thermal printing technology has become widespread across the globe for printing labels, tags and tickets due to its ease, speed and efficient output. These labels and tags can be the vital link in getting your product to your customer, promoting your brand, identifying your assets, or labelling for compliance. Today there are many different types and grades of labels and label materials available, and each can offer a different benefit. However if the label or label material is wrong for the application, the label can either fail to perform or conversely, offer poor value if 'over-spec'ed, so a comprehensive understanding of how and where the label is used is essential to determine the right label for the job.