Multivac files patent for cross web labellers
The company believes moving machines or machine parts increases the risk to operational safety such as crushing or cutting.
Crush hazards
According to Klaus Rocholl, technical services manager, Multivac Marking & Inspection, in Update internal newsletter, there is a potential danger when working with cross web labellers because for the labeller to travel over several pack rows, it has multi-row formats with a longitudinal shift.
This involves a crush hazard between the moving labeller and fixed parts of machines and buildings, such as hall pillars, control cabinets or the safety guards of the packaging machine.
“Such danger situations cannot always be kept under control by rules of behaviour. It is for this reason our labellers observe standardised safety distances,” he said.
All Multivac machines bear the CE mark, which comply with EU directives as well as DIN EN 349, which regulates the safety distances for avoiding crush injuries to the body. In the case of Multivac cross web labellers the safety distance is 500mm as body protection and 300mm head protection.
Rocholl added with individual applications, it is necessary to install two cross web labellers on one thermoforming packaging machine. One example is, if formats with a high number of pack rows have to be labelled at high speed. In this case, two cross web labellers share the work.
Two labelling units are also necessary for applying two different labels, such as a primary decorative label and a promotional one.
The installation of two cross web labellers one one thermoforming packaging machine requires safety distances on both sides of the labellers and between the units. In addition to the area needed to mount the machines it needs additional space for safety distances but this space is not always available and custotmers often want to install labellers with as much space saving as possible due to cost reasons, claims Rocholl.
One longitude shift unit
Multivac developed a tandem mode for cross web labellers in 2011 where two labellers of the same type are mechanically coupled together with one longitude shift unit, which means they can no longer move independently of each other.
“Multivac eliminated the risk of crushing injuries but the disadvantage of coupling the labellers together is the restricted functionality, meaning interruption-free operation is no longer possible,” said Rocholl.
“As soon as one label roll has to be changed, the whole packaging machine has to be stopped for safety reasons. To overcome this disadvantage of the tandem mode, Multivac has the TWIN option for cross web labellers and file a patent application for the concept.
“It is based on an intelligent distance monitoring device, which together with an external safety control unit permanently monitors the distance between the two labellers.
“As soon as one critical measurement fails to be met, the packaging machine stops immediately. The safety control unit is located between the drive controllers for the shift axles and the machine control, and the communication is performed via EtherCAT.
Objective is to retain space
“The objective is to retain the space-saving mounting of two labellers with one longitudinal shift unit while at the same time, enabling all those operating modes to be used, which can be achieved with the installation of two completely separate labellers.
“This includes interruption-free operation and label roll change when the packaging machine is running.”
He added, intelligent distance monitoring also enables one labellers and one bottom labeller to be installed on the same side of the packaging machine. This allows for operation on one side.
“Normally, labellers with the standard mounting are installed opposite each other, so that they have to be operated from two side,” said Rocholl.
“Where there are long packaging lines, this type of installation causes lost time due to long paths around the line, or it requires bridges to be built over the line. Intelligent distance monitoring increases safety and means labellers can be installed in an operator-friendly way.”
