Laser Marking on Paper

For the last fifty years the paper mill Jass manufactures environment-friendly paper for corrugated packaging. At both locations, Fulda and Rudolstadt-Schwarza, they have a total annual production of 950,000 tons. The locally produced corrugated materials and test liners have a basis weight of 80 - 300 g/m² and are made of 100% waste paper. In order to make sure that all necessary data is made available to the customer, the paper drums are printed with two different types of information. The first is a bar code on a label which is placed centrically on top of the drum to allow scanning from a fork-lift truck. The second information is the marking on both faces with grammage, weight, order number, the unwind direction and drum ID. For this purpose Jass in Fulda used an Ink Jet printer until the end of 2010. A well-engineered technology which however was not the right solution for this application.

As part of a plant modernization another solution had to be found. The new requirements were clear: improved legibility of the drum data, minimization of maintenance costs, as well as increased system availability. In addition to that, a robot would be used which was equipped to work in two steps, so the paper drum needed to be positioned only once for the marking process. This meant that the robot had to apply the label and mark both drum faces. But how could the information be applied on the face, if an Ink Jet printer was no longer an option? The only effective alternative is a laser system. It offers a very good legibility, operates without any consumables and is virtually maintenance-free. Thus, it was exactly the solution which Jass strived for. A laser for marking on paper was a novelty at that time in the paper industry.

The company Jass has always been good at breaking new ground. And with the laser they did precisely that. "The first trials have shown that marking with laser on paper is very promising," said Christoph König, director of the EMR department at Jass. “But the large marking area of the faces could only be achieved by multiple positioning of the laser and that took too long”. To improve this, another laser was tested which was then finally used: the REA JET CL CO₂ -Laser from REA Elektronik, a company that has offered contact-free marking in the industry for almost 30 years. From ink jet over laser systems up to spray mark technology - What makes REA solutions different from others and how does it perform in this application?

The laser REA CL used at Jass is a 30 watt CO₂ laser with the latest digital control of the deflection mirrors. Laser unit and controller are mounted onto the robot arm. The intelligent control system of the REA CL laser allows large-area marking while moving, which leads to a clearly reduced cycle time. Fast marking - one of the main requirements at Jass. An integrated pilot laser for fast and simple alignment is included within the standard scope of delivery. The controller is equipped with a graphic display and offers an intuitive user interface via control buttons and a rotary knob with push-button function. The interfaces range from USB ports over configurable digital I/Os, up to Ethernet, allowing a remote-controlled operation of the system if required. That is why the REA JET CL laser is well equipped for future requirements.

 

The newly installed robot from ABB is programmed in the first step to select the label from the labeling system with a vacuum plate and then attach it on the center of the drum. This labeling machine is from Teuto Systemtechnik, an affiliate of REA Elektronik. In the second step, the information such as grammage, weight, order number and drum ID are marked with a laser with two lines each, right and left of the central sleeve, on both ends of the drum with a character height of 30 mm. Upon completion of the marking process on one drum face, the robot arm with the laser mounted to it, swings over the paper drum to mark the second face identically. This marking needs to be done as close as possible to the center sleeve so that the information is visible even when the majority of the paper is already uncoiled. In addition, arrows indicate the uncoil direction for further processing. The laser receives the print messages via the Ethernet interface from a superordinated factory data collection system. The coordination between the laser marking and the movement of the robot arm is made via the digital I/Os of the REA CL controller.

“The security concept of the REA JET CL allows the integration into the security system of the complete system in accordance with the valid standards and guidelines”, said the surveyor for laser technology and laser safety Dr. Andreas Trautmann, who was in charge of the acceptance test.

The combination of laser marking and labeling with a robot has been in operation since January 2011 and was certified by Jass under valid European Union machine guidelines. It is the first application in the paper industry, in which a laser is deployed for marking. Even though the initial investment was higher - this combination is fully convincing, according to Christoph König, "on paper machine 3 we are currently processing a grammage of 125-140 g / m² and obtain with the laser for both, test liner and corrugated material, an excellent legible laser mark and this at a total machine set-up time for labeling and marking of approx. 60 seconds per drum. That is a savings of about 1 minute compared to the previous system”.

REA Elektronik GmbH

Teichwiesenstr. 1

D-64367 Mühltal-Waschenbach

Contact: Mr. Dr. Torsten Rickes