Labelling in electrical environments

Professional labelling is essential for clear assignment of components and cables in electrical systems for building installations. Efficient and flexible printing systems are now replacing prefabricated labels or manually applied labelling.

In the building installations sector, time is a crucial factor, just like in any other branch of industry. Industrial buildings, office complexes and other functional buildings are being built faster and faster. This trend is also affecting the electrical installation industry: whoever can make control cabinets the fastest will win the contract.

Choosing the right printing system

Every customer-specific building system design requires custom labelling. In the past, manufacturers would often order pre-labelled materials, but nowadays there is no longer time for this. With flexible printing systems, components can be custom-labelled in the factory or directly at the customer’s site prior to operation. Labelling volume is the key factor in choosing a printing system, and two different systems are used: individual labelling materials inserted manually or labelling materials automatically inserted in either roll form or in cartridges.

Thermal transfer printers for small to medium-sized labelling jobs

Traditionally, labelling plotters have been a popular choice for marking terminals and equipment used for small to medium-sized jobs. Plotters use solvent-based ink, which hardens when the solvent evaporates. This simple method has a disadvantage in that the labelling pens can easily dry out.

This problem is prevalent in all ink-based printing systems. Either the pens dry out or the printers must be thoroughly cleaned before they can deliver satisfactory results. The medium itself is problematic as ink-based systems contain solvents that give the ink the necessary viscosity. Solvents such as alcohol, oil or water evaporate into the air, leaving behind just the ink, which becomes a permanent part of the substrate. This process is difficult to control because evaporation depends on many different factors.

Ambient temperature, humidity and long intervals between operating times can also cause problems. Continual monitoring of the printing process is time-consuming and makes ongoing operations expensive. In addition, printer cartridges and dried-out pens pollute the environment.

Advantages of fixed-ink printing

One alternative to solvent-based labelling systems is thermal transfer printing, a method in which the ink is directly applied to the labelling material. The thermal printer head is a key element of these systems and is comparable to a pin-style printer head. The distance between the pins, which serve as heating elements, determine the print resolution. The current standard is 300 dpi (dots per inch), which allows for font sizes up to 0.5 mm. The ink is applied to the print medium wherever the heated elements contact the ribbon. The printed result is smudge-proof, resistant to alkalis and acids, and can withstand temperatures up to 150°C.

This fixed-ink printing system has several advantages including: low procurement costs, a compact design enabling mobile applications and constant availability, even during downtimes. Due to these advantages, thermal transfer printing is now widely used for printing labels and heat-shrink tubing in industrial environments. Flat roll-form materials are typically used as they are easy to feed through the printer and their flat shape makes them excellent for thermal transfer printing.

Contact-free printing for high-volume labelling

UV-based printing is no longer a new technology for labelling plastics or paper and has been used in offset printing since the 1950s. After printing, the printed area is illuminated by several UV lamps and the fluid on the labelling material is hardened by a high-energy, short-wave UV light (typically between 200-380 nanometres) in a process called polymerisation.This contact-free printing method has the following advantages: there are no drying times, the end result is smudge-proof and resistant to abrasion and to chemicals, as well as being solvent-free and environmentally friendly.

After the UV exposure, the surface of the labelling material is cool enough to touch. The material can be immediately processed after printing and is not placed under any thermal stress. If any part is missed, the material can be reinserted and printed.

In summary, the ideal printing system for labelling components in electrical environments is chosen based on workflows and print volume. Requirements regarding materials and the durability of the print result are determined by the application, with both ink-based and thermal transfer systems designed to meet the varying requirements of any project.