Published on : Friday, November 4, 2016
As a machine and plant engineering company with focus on the woodworking industry, Hymmen has an extensive know-how about the complete production procedures of their customers. Due to the close interaction with the customers of the furniture and kitchen industry, very soon Hymmen realised a special field of application for their industrial digital printing technology for which there had been no solution on the market so far: The industrial digital printing on edge belts.
The advantages of digital printing on edge bands
The substitution of gravure printing by digital printing provides a lot of advantages to the customers: The digital printing can be incorporated in existing process chains of the decor industry, it enables an individualized mass production, the quick reaction on market trends and customer re-quests, a shorter “Time to Market”, short set-up times, lower storage costs, no material loss upon change of decor, and, last but not least, new design options with regard to register lengths, levels of detail etc.. On request, this is matched 1:1 to the decor of the board surface – possibly finished by the same company – (comparison of gravure printing and digital printing see fig. 2). Thereby, the whole line has a very compact design. We succeeded in accommodating the whole technology on a minimum amount of space, without having to renounce the advantages of large digital lines like e.g. the automatic cleaning of print heads.
The vacuum precision conveyor as a result of elaborate R&D
Two of the 32 digital printing lines sold by Hymmen are the special type JUPITER JPT-WS for digi-tal printing on edge bands. Significant research and development efforts have been managed be-forehand. We had to find a solution to handle the special features of the substrate. This was finally found in the curved high-precision conveyor for edge material.
Two line variants: Inline and Offline
The digital printing line JPT-WS is available in two production widths: 230 and 560 mm, with a dif-ferentiation between the variants inline and offline. Both types are available for integration within an existing edge band production line with extruder and liquid coating machines. Printing takes place here on a single track, borderless over the whole edge band at a maximum effective printing width of 205 mm resp. 410 mm. In case of the inline variant, the primer, basic lacquer and, if re-quired, the texture are applied on the edge belt. The digital printing is followed by the coating lac-quer and profiling, as far as this was not carried out before. At the end of production, the edge band is wound up on rolls and supplied to the end customer.
However, these lines can be also installed offline as independent printing machine. In this case it contains a rewinding and an unwinding station (compare fig. 3a and 3b). All edge printing lines are very compact and do not need a lot of space in the production hall. With the calender in front of the digital printer and the calender behind it and the vacuum precision conveyor, the wide line installed inline is approx. 7,50 m long, 3,70 m high and 2,70 m deep, for example. With a printing speed of 25-50 m/min, edge belts of up to 4 mm thickness can be printed. The edge band travels approx. 13 m in the Hymmen line, incl. the “loops” along the calender. If this happens with a speed of 50 me-ters per second, the belt is digitally printed and dried with 16 seconds. The materials to be pro-cessed are PP, ABS or PVC edge bands before of after their cut to size.
In addition to the high precision conveyor which ensures the flatness of the substrate by means of the vacuum suction, the digital printing machine for edge bands offers further technical highlights. The modular width extension implies flexibility with regard to the printing widths. The self-recovery function ensures a very high line availability. Calenders within the Hymmen line enable a decou-pling of the web tension within the digital printer from the web tension in the periphery. The grey scale technology ensures a print image in reliable and uniform high-definition quality up to the bor-der of the edge, while the color management is easy to handle at the same time.