Alignment Variance
Positional shift between successive colour plates during a high speed multi-colour printing operation defines register drift. Mechanical oscillations within the web transport system or thermal expansion of the substrate during the drying stage trigger this phenomenon. Precise synchronization of the impression cylinder and the blanket cylinder prevents image ghosting or colour halo effects.
Strict control over substrate tension ensures the repeat length remains consistent across the entire web width.
Tolerance Standard
Print houses maintain strict thresholds to ensure visual fidelity across long production runs. A deviation exceeding a small fraction of a millimetre frequently necessitates immediate recalibration of the tension control loops or the servo motors driving the units. Digital camera arrays mounted after the final print station detect microscopic shifts in registration marks.
These systems provide real-time feedback to the central processing unit, allowing for instantaneous adjustments to web position or cylinder speed without halting the press. Consistent measurement against the master reference mark determines the acceptable deviation limit.
Material Influence
Hygroscopic substrates absorb humidity during the printing process and undergo dimensional changes that compound mechanical errors. Paper stocks with high moisture content expand or contract when exposed to the heat of infra-red or hot air drying tunnels. Operators manage these distortions by adjusting the internal press temperatures or slowing the line speed to allow the substrate to stabilize.
Control of environmental variables in the press room acts as a primary defense against unintended dimensional fluctuation. Consistent climate regulation remains the primary method for maintaining registration accuracy in heavy offset printing operations.
