WHY ENGRAVING HEAD MAINTENANCE?
HELL offers comprehensive customer support for the highest possible availability of its high-performance engraving systems
Extraordinary performance is always demanded of HelioSprint engraving systems. But for consistently high engraving quality, regular servicing is essential.
The challenge: speed, precision, repeatability
HelioSprint engraving systems must deliver the highest possible performance on demand. They engrave 8,000 or 12,000 cells per second with a depth of up to 70 µm and a required accuracy of 1 µm! This precise repeatability must not only be maintained for each use of the cylinder, but also after engraving over 10,000 cylinders!
No ideal engraving system exists
An ideal engraving system would transfer an image signal with a 1:1 mechanical movement, e.g. the rectangular signal of a black-and-white transition. No error patterns like bouncing, tracing or thermal drift would occur. In practice, however, there is no ideal engraving system. Material properties, magnetic effects such as hysteresis as well as unavoidable manufacturing tolerances always lead in practice to deviations from the ideal transmission behavior.
Error compensation via fingerprint
HELL has developed a calibration process that uses digital signal processing to compensate for deviations from the ideal. It records the characteristics of the engraving system with a variety of measurements and then determines a so-called fingerprint. The fingerprint is stored in a memory component of the engraving system. Before each engraving, the fingerprint is read out and sent to digital signal processors in the engraver. During the engraving process, the processors calculate a corrected image signal based on the individual fingerprint, which counteracts the error patterns (see above) of the respective engraving system.
The hazards of everyday life…
In daily production, the engraving system is exposed to various influences that can negatively affect its transmission behavior. Improper handling such as hard setting down, damage, dirt, cooling problems or also aging processes lead to changes in the characteristics of the engraving system. The use of non-certified engraving styli can also lead to this effect!
… HELL’s solution
To ensure consistently high engraving quality, it is essential for engraving systems to be regularly serviced and returned to their factory default condition. The systems are taken apart and cleaned; defective or worn parts are replaced and the fingerprints are renewed. Systems requiring maintenance are subject to the same quality checks as new heads! After maintenance, another engraving process – with customer parameters if desired – is carried out.
Error on the cylinder surface: Bounce
Error in printing: Bounce
Error on the cylinder surface: Drag
Error in printing: Drag