Orders up to 2.8 m (110”) printing width have special requirements in prepress at Glatz Klischee and in printing at Hans Kolb Wellpappe.
Written by Dieter Finna
When corrugated cardboard packaging from the world’s leading power tool manufacturer Stihl exceeds the maximum photopolymer plate format of 2 meters (80”), the prepress department at Glatz Klischee is required to convert this into suitable large format assemblies for flexo screen printing. The Innovalux foam substructure with a fleece backing has proven itself. The advantages of this solution can be seen in the handling of the assemblies in prepress as well as in printing.
As is so often the case, it’s the fine details that make the difference. This also applies to the extra-wide printing forms in direct corrugated cardboard printing. The requirements of these printing forms are essentially defined by the two individual components made of photopolymer plates and foam substructure. Due to their dimensions, both have special requirements in terms of processing and printing. In the case of photopolymer plates, the requirement arises from the plate format, which is only available up to a size of 1,270 x 2,032 mm (50” x 80”). As a result, a printing form in large format up to 3 m (118”) width cannot be produced from one piece. With the foam substructures, the challenge lies in the consistancy of the material properties over the entire printing width. Glatz Klischee has found its own solutions for both and combines them into joint large format assemblies for high-quality screen flexo printing.
Mounting options up to 3m print width
The basis of the large format assemblies for the corrugated cardboard post-print is a foam substructure from Innova Flexo Products, which is available at Glatz Klischee, prefabricated on a polyester film, laminated in various widths.
In a first step, a plotter draws the die cut precisely on the polyester side of the foam substructure and cuts it to the required format. With Glatz Klischee, the maximum mounting width that can be processed is 3 m (118”).
Design-appropriate, creative solution
The creative work step in prepress then lies in the assembly of the printing plates. The necessary cut through the design and thus through the photopolymer plates is chosen so that as few parts of the image as possible are affected. This requires a great deal of experience, as the cut also goes through screen elements of the print design. “Thanks to the long-standing partnership between Kolb Wellpappe and Glatz Klischee, there is a great deal of experience in terms of technical possibilities, which means that such specialties can also be implemented,” says Manfred Schattenthaler, Managing Director at Glatz Klischee, underlining the possibilities in the growing collaboration with Kolb.
In the print it is then hardly visible that it is a butted assembly. The marked plotter lines, which can be used to identify whether the cut is in the correct position, provide assistance with the panel assembly, where the edges of the packaging design are located.
Conversion to the Innovalux substructure
The Innovalux foam substructure has proven itself at Glatz Klischee for working with jointed assemblies. Holger Stier, Technical Management, names several reasons why Glatz has switched to the substructure from Innova Flexo Products and prefers it for this work. “On the one hand, it was the low tolerances of the substructure that made it particularly suitable for large format butted printing plate assemblies. In addition, the Innovalux foam substructure is very constant in its compressibility over the entire width, which leads to a precise, stable expression behavior. And it has handling advantages thanks to its fleece on the back ”.
“On the one hand, it was the low tolerances of the substructure that made it particularly suitable for large format butted printing plate assemblies. In addition, the compressibility of the Innovalux foam substructure is very constant across the entire width, which leads to precise, stable expression. And it has handling advantages thanks to its fleece on the back, ”says Holger Stier, Technical Manager at Glatz Klischee, explaining the reasons why Glatz Klischee switched to the substructure from Innova Flexo Products.
With the help of a plotter, the cutting form is transferred to the Innovalux foam substructure. (Source: pack.consult)
Handling advantage when printing
Similar to the printing machine, the large format assembly at Glatz Klischee is hooked into the proofing machine. The fleece back of the foam substructure makes it easier to position the post-print assembly, which, with its 2.8 m (110”) width, is much easier to wrap around the cylinder. Given the size and weight of the printing form, this simplifies the handling of the extra-wide assemblies for the operator compared to a variant with a smooth foam back.
Advantages also when setting up in print
The large format assemblies of the Stihl packaging are printed at Hans Kolb Wellpappe in Memmingen. A Göpfert Evolution 1628 HBL 5-color machine with an integrated punch is available there, which can process a maximum sheet width of up to 2,800 mm (110”).
The hanging of the post-print assemblies during the setup process in the printing cylinder is done jointly by up to two printers, as they manually support the assembly process over the entire width of the printing cylinder. Assemblies with fleece backs do not stick to the cylinder as strongly as assemblies with a smooth back. This is particularly important with damp printing cylinders. “If the cylinders have got a little damp when cleaning the plates, assemblies with a rougher back can be angled better,” explains Wolfgang Prinz, machine operator at Kolb, about the better handling of assemblies with a fleece back. After about 30 sheets, the angle is readjusted to compensate for any distortion of the assembly on the cylinder, which is easier with a post-print assembly with a fleece backing.
“If the cylinders got a little wettish when cleaning the plates, the plate assemblies with a rougher back can be positioned better,” explains Wolfgang Prinz, machine operator at Kolb, about the better handling of assemblies with a fleece back.
Various foam substructures are in use at Hans Kolb Wellpappe, which means that we have experience with the types available on the market. According to Kolb, assemblies with an embossed foam back are more difficult to handle in the machine because, despite their embossing, they have a significantly smoother back than a fleece and thus adhere more strongly to the cylinder surface. In the case of assemblies with a fleece surface, the fleece reduces the adhesion and the assembly slides better on the printing cylinder.
Kolb specialists Thomas Eggart and Wolfgang Prinz setting up the large format assemblies on the printing unit. The cutting line in the joined set of plates can be clearly seen (source: pack.consult)
Stable in impression behavior
The fleece substructure has also proven itself at Hans Kolb Wellpappe due to its stable impression behavior. With the Stihl print design “Battery reach trimmer light 01”, this comes into play across the entire printing width, as the Stihl company logos are placed in several places in the design and on both ends of the packaging. The Stihl orange, made up of yellow and magenta in the print design, would react immediately to tolerances in the substructure with color fluctuations if different thicknesses or irregularities in the compressibility of the foam sheet were to cause this. Checking the set-up by the printer shows the expected good result with the Stihl Orange, with a uniform color tone across the entire print width as well as within the print motif.
The good result in the printout behavior of screen and solid surfaces is based on a uniform corrugated board quality as well as the good coordination of the printing machine and post-print assemblies, with very low tolerances for photopolymer plates and foam substructure, which is a decisive quality criteria, especially for the extra-wide assemblies.
What constitutes the substructure