The logistics industry favours thermal printing due to its ability to produce accurate images with excellent edge definition, making it ideal for printing barcodes. There are two thermal printing methods available; Thermal Transfer and Direct Thermal.
In Thermal Transfer, a thermal print head applies heat to a print ribbon contain ink. That ink is melted onto the label to form the image. Direct Thermal requires a thermal sensitive label that the print head will heat directly to form the image. Both methods have their advantages and disadvantages. Below is a list of things to consider when selecting a printer.
Media
Direct Thermal requires a chemically treated, heat-sensitive media, whereas Thermal Transfer can accept a wider variety of media, including paper polyester and polypropylene materials. Furthermore, Direct Thermal media is sensitive to heat, light and contact (rubbing), so it is only suitable for applications where the label’s life is less than 12 months and is not exposed to fluctuating temperatures or direct sunlight.
Consumables and Maintenance
Consumables are the critical difference between the two printing methods. The thermal sensitive media required for Direct Thermal can be costly; there are cheap alternatives out there that vary in quality, significantly affecting barcode readability.
One advantage Direct Thermal has over Thermal Transfer is that it does not require a print ribbon. Along with the benefit of not purchasing and maintaining a supply of print ribbon, it reduces downtime when having to replace the ribbon and errors introduced during ribbon installation, such as ribbon wrinkle.
Print heads wear different between Thermal Transfer and Direct Thermal as the print ribbon protects the head from dust and debris. Therefore, cleaning and maintenance of the head can increase the lifetime of the head.
One of our suppliers state that a Thermal Transfer printhead will last approximately 1 to 2 years, whereas a Direct Thermal Printhead’s lifetime will last approximately 50-75% of the Thermal Transfer printhead, roughly equating to 3 printheads every two years.
Cost
The cost difference is hard to determine as it is dependant on the quality and quantity of the labels, environmental factors, and how well the equipment is maintained.
If you are concerned with the cost to operate. In that case, the printer supplier could assist by providing a cost comparison. You would need to supply some details, such as the size of the label and the frequency of printing required.
The general consensus seems that Direct Thermal Labels will cost more than Thermal Transfer labels plus ribbon; However, operational costs of maintaining the supplies of ribbon and the time to change ribbons increases cost as ribbons and labels are often not changed at the same time.
Industry Preference
The label printer suppliers that I work with state that the industry prefers the Direct Thermal approach. 80% of one supplier Label Printer Applicators (LPAs) sold are Direct Thermal. However, it should be noted that our LPA suppliers are much more active in the FMCG production space rather than the logistics (personal observation).
My Preference
I prefer Thermal Transfer over Direct Thermal due to Thermal Transfer’s barcode print quality and speed. Speed of printing is interesting as Direct Thermal printing seems to have increased in recent years, and I’ve read conflicting opinions from Label Printer suppliers on this; it may also be that their documentation is not up to date.
If speed is a critical deciding factor for your application, then I would recommend raising this with the supplier.