As a manufacturer of marking equipment and engraved wheels, supplier of inks and consumables, Siba is not only offering efficient items, but a global comprehension of customer’s needs and a complete assistance, from the enquiry to the commissioning of the equipment.

The first impression always remains the most important one. Looking at the best cable of the world, the first detectable thing on it is the printing, more especially the quality of the printing. This is the best visit card of the cable manufacturer and it immediately reflects his reliability and his excellence. This is a significant sale argument as well.

However, achieving this impressive printing quality is not only the consequence of a pure printing process and operator’s skills, but the result of a global working environment, combining numerous parameters, sometimes underestimated in whole production process of cables.

The suitable equipment at the suitable location

Right from the conception of a new extrusion line, the location of the marking unit should be carefully considered. Depending on the insulating material, this marking unit can be integrated after the extrusion head or after a cooling bath.

If the insulating materials are PE or XLPE for instance, using the surface heat of the cable is an advantage to improve the ink adhesion. In that case, the marking unit should be integrated as close as possible to the extrusion head, but after a short cooling bath, to reach a surface temperature of 80-100°C.

For printing on PVC material, there is no need for special hot cable surface to improve the ink adhesion. Printing on PVC is quite easy and can also be achieved off line, at room temperature, at a rewinding station for example.

In any case, if the printing occurs after a cooling bath, which often happens in online printing process, it has to be made sure that the cable surface is perfectly dry. If any thin water film appears on the surface of the cable before the printing, the ink will simply not stick on the cable surface, even on PVC. For new lines installation, it’s recommended to plan enough room to integrate the appropriate marking units (Si20 or compact Si10 for example) in order to benefit from these advantages.

Advantages and difficulties to print on hot materials

Even if printing on hot materials (PE, XLPE for example) offers the big advantage to improve the ink adhesion, this printing process is a delicate issue that requires more attention from the operators and adapted settings of the marking unit.

The main problems appear when the cables are too hot, as they may remain stuck on the printing wheels and/or may be deformed. By high printing temperature, the ink is also drying faster and the solvent evaporates quicker. The global warm-up of the printing station increases the wear grade of both wheels and scrapers.

To avoid these inconveniences, the tank of the ink pump unit should be connected to the whole cooling circuit of the extrusion line. The last generations of marking systems dispose of cooling circuit integrated in the ink tank of each pump unit.

To facilitate the work of the operators, it’s recommended as well to connect the marking unit to a viscosity control device (Vi200 or Vi210), to constantly control the optimal ink viscosity, by automatic adjunction of solvent. The viscosity value will be pre-set from the beginning and will be automatically maintained during the whole printing process, without any effort or particular attention from the operators.

Good printing quality is the result of operator’s skills

Despite all the technical improvements offered by the new generations of marking systems and ancillaries, skills of the operators remain the main factor to perform a quality printing.

Not only the experience is important, the operators have to be familiar with the equipment they work with and have to be properly trained to be more attentive to the tasks to be achieved during the printing process:

Regular control of the printing quality with the synchronised stroboscope lamp (SiLux) or with hand-held stroboscope lamp (SiLux 3000D / SiLux 3000A).
Sufficient quantity of ink to be sprayed on the wheel circumference, acting as a lubricant and preserving the lifetime of the wheels.
Appropriate setting of the scraper position and pressure, to assure a clean printing.
Clean working environment.

The gravure ink, an other key factor of success

Last but not least, the choice of the suitable gravure ink is a very important point, to perform a contrasted and shiny printing and to guaranty the optimal adhesion. Two parameters have to be considered; the material to be printed on (PVC, PE, XLPE, Hytrel) and the average printing speed (up to 500 m/min with TD 500 or from 500 to 1200 m/min with TD 1200).

To be sure to use the appropriate type of ink for a specific application, trial tests are recommended. They make sure that all quality criteria are strictly observed, and they offer the advantage to pre-define the optimal setting parameters.