VIDEOJET 8520 - Shaft Encoder Extension Cables

9-14 Terminals Rev AB
Videojet 8520 Operator Manual
Incorrect pulses per meter ratio set on the Videojet 8520
If the ratio of pulses per meter set on the Videojet 8520 is identical to the
actual situation (example: a different measuring wheel, measuring wheel
is not in direct contact with the belt, different shaft encoder), the print
image will either be stretched or compressed lengthwise. If the printheads
print with both nozzle rows, the two print images created by the two
offset nozzle rows will not be exactly aligned with each other. A shadow
appears. If the print image is made up of several printheads, an offset will
also be visible at the transition from one printhead to the other.
Slippage on the measuring wheel on the shaft encoder
If the shaft encoder is not pressed onto the conveyor belt with enough
pressure or is in contact with a very smooth surface (example belt driving
roller), the shaft encoder may occasionally slip and the Videojet 8520 will
then receive incorrect speed information. In the print image, this is
apparent in stretching in the print direction and an offset at the printhead
transition points. Another problem occurs whenever heavy products are
on the belt, causing the shaft encoder to jump off. In the print image, this is
apparent in missing prints and offsetting. If the pressing pressure on the
belt is excessive, the shaft encoder bearing may get destroyed.
Insufficient number of pulses per revolution (less than 500)
If you print with a low belt speed or the belt is accelerated or slowed down
during printing, it is possible that the automatic adjustment of the printing
speed may be slower. This will result in an imprecise print image
(stretching, compression, offsetting at the transition points between the
printheads if several printheads are used). If the speed of the belt is too
slow, the Videojet 8520 interprets this as a stop. It is advisable to use a
shaft encoder with a large pulse/revolution ratio for very slow belt
speeds.
Shaft Encoder Extension Cables
The standard shaft encoder is available with a connection cable in various
lengths. Videojet also offers a range of extension cables in different
lengths.