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FlexoGravureGlobal
The Leading Technical Magazine for the Paper, Film and Foil Package Printing and Converting Industries
www.flexo-gravure.com
Retrofit of a 40-year-old gravure press
Experience
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For reasons of costs alone, invest-ment in a new gravure press ne-
ver was an option for us,” explains André Wachtmeester. Together with the Styling/Printing Manager of Forbo Flooring Systems in Coe-vorden in the Netherlands we are standing in the control centre of the Erwepa machine that was in-stalled in 1977. We are looking at the four meter wide, completely printed and embossed web of a grey-brown flooring made of 0.6 mm PVC composite that is running through the “command centre” at the end of the printing machine, fi-nally leaving the machine in the direction of the reel.
“Furthermore, this machine of-fers some special features like its extra-wide web. We did not even check whether there is still a man-ufacturer who is able to deliver a gravure press that meets our re-quirements,” points out André Wa-chtmeester, stating that there had never been an alternative to the retrofitting of the existing machine at Forbo Flooring Systems. In addi-tion to this, an increased number of vinyl floorings are set to be pro-duced by digital printing in Coev-orden in the future; today, just over ten percent of the floorings are produced using this method. Cur-rently, large-format digital printing
is not able to compete with gravure printing with regards to speed and repetition accuracy. However, it will surely catch up in the near fu-ture. Correspondingly, everything pointed to completing the modern-isation of the present technology.
“Above all, we wanted to reduce our waste and improve printing quality. Furthermore, we hoped to be able to break new ground in the manufacturing of floorings when completing a retrofit,” says André Wachtmeester looking back to the end of 2013. At that time, Forbo Flooring Systems contacted BST eltromat International to discuss the possibilities regarding the mod-ernisation of the gravure press that is almost 40 years old. “The ma-chine with the eltromat register control DGC-650 has been in oper-ation since 1999. We knew that the automation department of this company has the required practical know-how as it has successfully completed a multitude of sophisti-cated projects in the past.”
The main shaft had to be discarded
In March 2013, BST eltromat pro-posed the removal of the main shaft, i.e. to discard the previous main drive of the gravure press, and to replace it with individual
Jörg Donnermann
Significantly reduced waste and higher printing quality in combination with improved user friendliness and freedom in development of new designs – Forbo Novilon has used mechanical re-design and state-of-the-art automation technology to raise the performance of its 40-year-old gravure press for PVC flooring to a new level. It has also proved possible for the safety of the employees to be increased and adapted to today’s needs. In addition to BST eltromat International as the leading partner of the company, the companies Interflex, Jansen Antriebstech-nik and Siemens also participated in this sophisticated retrofitting project.
Retrofit of a 40-year-old gravure press
Left: The web, with a width of four metres, runs through the gravure press at a speed of 50 metres per minute
Right: The cable trays offer a clear arrangement and suffi-cient capacities for possible further modernisations
Experience
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dré Wachtmeester: “The touch of a button will be sufficient for this.” In the past, the doctor blades had a fixed transmission ratio due to the rigid connection to the gearing so that their speed was always identi-cal to the machine speed.
The good accessibility of the whole technology represents an-other benefit, enabling a simple and quick replacement if needed. “We now have more space for movement within the machine. This also enables faster access,” says the manager whilst we change sides between two printing units via an aisle approx. 1.5 metres wide. “In the past this would not have been possible because the
drives for each of the six printing units – with all the benefits offered by such a configuration allowing more flexible control of the ma-chine. This means that, in addition to modernisation of the automa-tion technology and register con-trol, the necessity for a larger me-chanical intervention had already became apparent at the beginning of the project. For the professional completion of such an interven-tion, the experts of BST eltromat also recommended getting Jansen Antriebstechnik GmbH from Viers-en and Interflex from Bielefeld in-volved, as they specialise in me-chanical retrofits, because they had previously cooperated with them successfully during several previ-ous projects. However, the techni-cal service of Forbo Flooring Sys-tems insisted on using the latest TIA-based (Totally Integrated Au-tomation) Siemens technology for the drives. Thus, the project includ-ed employees from five companies, completing the concept in May 2014.
After the general approval of the concept, BST eltromat prepared a test design including new drive technology and register control, providing a practical visualisation of the mode of operation of the new automation technology. In July 2014, twelve employees of Forbo Flooring Systems attended a technical training day at Ostwest-falen-Lippe. André Wachtmeester: “That day we got to see the techni-cal benefits of the planned mod-ernisation. Now it was clear that we would be able to meet our ex-pectations with a comparably low investment.”
Every printing unit with its own drive
Before the retrofitting, the main motor not only operated the six printing cylinders, but also the doctor blades, via a special gearing and chains. This was not possible after the retrofitting because the re-moval of the main shaft also re-moved the mechanical system and the inherent drive train for the doc-tor blades. Instead, the concept for the doctor blades provided small frequency converter motors made by Siemens that were intended to
replace the gearing. This was also able to reduce the required cabling because the motors are only re-quired to receive the control sig-nals from the control cabinet via a bus and the 400 V power supply via a second cable.
This concept offers Forbo Floor-ing Systems a range of benefits re-garding the two-layer production of PVC flooring using the gravure press: as any printing unit is equipped with a controlled drive for the doctor blade, the blade speed can now be individually pre-selected. This enables the ma-chine operators to accelerate the doctor blades in the case of a pos-sible development of streaks. An-
André Wachtmeester (left) and Stefan Gregor (right) had the drives installed vertically
The showroom of Forbo Flooring Systems in Coevorden in the Nether-lands presents the comprehensive range of PVC floorings
Experience
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main shaft would have blocked our way. Furthermore, the drives are installed in an upright position so that they do not extend into the walkway”, says André Wacht-meester whilst pointing at one of the motors that are installed in a vertical position directly in the printing units. “This is also a very convenient feature for our machine operators.” In the case of malfunc-tion they can access the corre-sponding site faster than ever. Last but not least, the new technology is also cost-efficient.
Innovative register control for more options
The gravure press now uses a regis-tar 20 register control made by BST eltromat, developed for in-line printing machines of all customary printing techniques. In addition to the high computing power, this in-novative PC-based system is also characterised by the high quality of its sensor system, which is com-posed of a light conductor system and an integrated camera. There-fore, even poorly visible print marks no longer represent a limit-ing factor. “Today, we can virtually see the white eagle on the white background,” says André Wacht-meester with regard to the daily production. Contrary to “the need to rely on virtual parameters” as in the past, the printing units can now be measured in terms of each other, enabling fine tuning of the whole process. This may well make Forbo Flooring Systems the only print shop in the world that is able to emboss over a width of four metres in register.
This is complemented by a high degree of automation in the case of repeated jobs. The new register control at Forbo Flooring Systems is connected to the machine con-trol via an interface which is used to exchange information between both devices. With every new job, the machine operators adjust the required printing cylinders by sight; they then start the machine and complete the fine adjustment. As soon as the machine is within the register, i.e. it is ready for pro-duction, a button for saving the production parameters can be pressed on the main operating con-
sole. Then, the positions of the printing cylinders are measured relative to each other. The angular offset is measured and included in the calculations; the correspond-ingly calculated value is then as-signed to the job and stored in the register control.
In the case of repeat jobs, the ap-propriate data can be retrieved at the touch of a button. The machine operators only have to insert the cylinders and switch on the ma-chine. Even before the web starts to run, the cylinders automatically move to the required position; here, it is important to know that Forbo Flooring Systems has more than 750 different cylinders available for production of PVC floorings. This amount makes it clear that the possibility of saving job data is highly important for the company.
Approx. one fifth less waste
Although the previous register control enabled pre-setting within certain limits, the new settings have significantly reduced the waste generated during the start of operations. As the six printing units are now driven individually, the machine operators can optimise the material throughput and there-fore reduce waste. Thus, the gener-ated waste with repeat jobs during full use of the machine is now less than one machine length. Given a rate of six to ten new jobs every day, this means high cost savings when considering the web width of four metres and the high costs for the raw materials. “Altogether, we reduced our waste during start by approx. 20%,” estimates André Wacht meester. “This particularly applies to the more difficult pro-duction work we do using light colours such as white and silver.”
Another benefit is the high availability of the machine thanks to the significantly reduced set-up times. The machine operators can now store additional information together with the job data in the control unit, thus further simplify-ing the set-up process. This is used in the case of deviating cylinder circumferences, for instance. The factory owns a multitude of cylin-ders which have been processed several times over the years so that
their circumference is less than 1,500 mm. Thanks to the individual drives, the speed of these cylinders can be set individually and adjust-ed to the speeds of the other cylin-ders. The machine operators save the corresponding data in the con-trol unit so that they can be re-trieved within seconds at any time in order to set the drives to the re-quired speed.
New possibilities for the design of PVC flooring
At the same time, this possibility means more flexibility regarding the use of the machines at Forbo Flooring Systems because the com-pany can now insert the cylinders into the gravure press in any order, and may consider the slip via the individually controllable drives. “As we are no longer required to insert the cylinders according to size, but are able to flexibly equip
Today, all the printing units of the gravure press are driven by individual drives
Experience
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the individual printing units, we now have various possibilities re-garding the combination of cylin-ders and the design of the flooring,” explains André Wachtmeester with regard to the daily business.
The retrofitting of the gravure press has also made the whole ap-pearance of the machine more at-tractive for the machine operators – everything is clearly arranged now. Cables are installed in trays, which mean there is sufficient ad-ditional space for further moderni-sations.
Another important aspect: the retrofitting was used to specifically increase safety of the machine op-erators. This includes , the elec-tro-mechanically locked covers at the drives can only be opened if the machine stops and the material web does not move. Furthermore, safety-checked PLCs and motors with on-board safety were used. Altogether, this represents a good compromise between safety and user friendliness that ensures the
employees comply with certain procedures.
Extremely tight time frame
In addition to the sophisticated technical requirements, the project team also had to deal with a par-ticular challenge: the retrofitting and re-commissioning of the ma-chine had to be performed and completed within the three weeks of the company holidays at Forbo Flooring Systems in July 2014. This meant that the given time frame was very narrow, thus requiring scrupulous preparation by all of the parties involved. “We were able to finish our work three days in ad-vance, and pre-produced some jobs even before the end of the summer holidays”, says André Wacht-meester. The involved Forbo em-ployees were so enthusiastic that they did not want to stop working. “Come on, just one more job.”
The new technology has been running on a stable basis since its
commissioning. However, if needs be, the experts at BST eltromat can still use remote maintenance to ac-cess and update the whole machine control, including the register con-trol. For example, the latest version of the HMI user interface was in-stalled via remote access. Even in this regard, the 40-year-old gra-vure press is state-of-the-art.
Forbo Flooring Systems
Forbo Flooring Systems is a com-pany of the Swiss Forbo group which is listed at the Zurich stock exchange and is a global provider of high-quality floorings. Its prod-uct range includes linoleum and object vinyl flooring, carpet tiles, Flotex flock velours, Coral active clean-off products, and vinyl floor-ing. The factory established in Coe-vorden in the Netherlands in 1979 has approx. 300 employees today and specialises in the development and production of high-quality vi-nyl flooring.
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