Air vane motor helps gravure printer make an impression

Packaging plays a major role in consumer preference: most purchasing decisions are made on the spot, in just a couple of seconds. The design, shape and presentation of the pack make the difference, guiding consumers towards making their selection from overflowing retail shelves and multiple products.

“In this respect we have a wide variety of opportunities to create value-adding refinements to the product and make it stand out from its competitors,” said Achim Kurreck, Managing Director of H.C. Moog GmbH. Kurreck works with an extensive range of packaging and so is well placed to observe market trends.

For decades, the machine engineering company has developed and built sheet-fed gravure printing presses to produce high-quality packaging materials. Despite global predominance of offset printing to produce packaging and high-finish printing, the family-run business has cornered a niche market as a sheet-fed gravure printing specialist.

But what is gravure printing? In gravure printing, the printing elements are in the form of etched depressions known as cells, generally produced by laser onto the printing form (cylinder or polymer plate). Before printing, the entire printing form is dipped into an ink bath, with excess ink at the surface removed by a blade. Only the ink for printing remains on the cells. The impression roller presses the material to be printed onto the image carrier. The contact pressure and force of adhesion transfer the ink to the material. The depth and screen width of the cells define the colour intensity; the graphic quality is excellent and in high resolution.

Since 2011, a Moog gravure printing press has been in production at Amcor Tobacco Packaging in Switzerland - a global player in the responsible packaging market. The press produces cost-efficient, quality mock-ups and short print runs in excellent print quality.

The Moog1 TBR Compact 740/1040 is a multifunctional machine providing the maximum sheet format of 740 x 1040 mm and a maximum output of 12,000 sheets/h. It permits sheet-fed gravure printing on conventional gravure cylinders as well as on digital photo-polymer plates. “All our experience gained from sheet-fed gravure printing is incorporated into this new design,” stressed Kurreck.

“The core piece of the machine, the double-circumference impression roller, is made from high-quality casting. This means that we were able to raise the linear pressure for embossing a little higher without having a negative effect on the machine’s service life.”

Moog designed new ink sumps to transfer the ink to the print cylinder. “We achieve the optimum mixture with minimum ink quantities, which makes the products more environmentally sustainable when recycled, while also reducing printing costs,” said Kurreck.

To adjust the height of the ink sumps, the manufacturer needed a drive that could be deployed in a potentially explosive atmosphere. The choice made was an air motor from DEPRAG Schulz. A 400 W Basic Line vane motor was installed on the ink sump at the very heart of the printing mechanism. With a nominal speed rating of 60 rpm and a basic torque of 63.6 Nm, it adjusts the height of the ink sump.

An air vane motor operates on a simple principle. The compressed air by which it operates sets in motion the rotor which rotates inside an eccentric cylinder. Vanes are inserted into the slots of the rotor and the centrifugal force that arises presses them against the cylinder wall. This creates work chambers for the expanding compressed air. As it expands, the compressed air converts the pressure energy into kinetic energy, causing rotational motion. Since the air is not under stress the vane motor remains cool, so cannot overheat. Compressed air is an intrinsically unproblematic energy resource - there are no hazards created by electrical contacts and leads.

All Basic Line air motors are ATEX-approved as standard for use in potentially explosive atmospheres, so Moog did not need to spend additional time or money getting ATEX compliance.

Air vane motors are fully robust and low on maintenance. The only parts that need replacing at specified intervals are the vanes. And when this is necessary, the maintenance engineers do not have to dismantle the air motor. “Our Basic Line air motors have a patented vane exchange system which means they can be replaced in just a few minutes,” explained Dübbelde. The air motor remains in its assembled position while the vanes are replaced, saving time. Once the screws have been loosened and the roller removed, tweezers are used to easily remove the vanes and insert new ones.

Kurreck places high value on the level of cooperation with Deprag’s customer advice and service. This was another reason for equipping the new Moog1 TBR Compact with the Deprag motor. “In the interest of our customers, we place great value on using quality German products with the corresponding guarantees as well as the possibility of using spare parts of the same construction,” Kurreck said.