January 29, 2014

5 Min Read
Conveyors treat cookies tenderly

Food production makes special demands on technology. This applies even when packaged cookies are transported in the factory. Jan Esselmann, system technician at United Biscuits' plant in Zaandam, Netherlands, knows about all these problems. He has spent 17 years trying to figure out the best way to transport packaged cookies and snacks between individual production stations. "You can't avoid crumbs when making and packaging cookies, which creates special transport problems," he says.

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When the company moved its shortbread production facility to Zaandam, northwest of Amsterdam, the timing was perfect to exchange the old packaging machines and chain-conveyor system for cutting-edge technology and simultaneously automate the final packaging process. In order to comply with space limitations in a factory that is more than 100 years old, a special project group planned the new system layout. "We didn't move production to the industrial area on the outskirts, which means we had to calculate very carefully how to best use the available space in the factory in the city," emphasizes Esselmann.

The group came up with three essential criteria during its search for just the right system: long conveyor sections, varying chain widths in one program and little effort necessary for maintenance and cleaning. "These three were really the most important requirements, and the VarioFlow chain-conveyor system from Rexroth (www.boschrexroth-us.com) meets them all," says Esselmann. Working together with Rexroth, the company was able to set up the new conveyor system in just a few months' time.

Shortbread production is spread over two levels in the factory. The cookies are baked in an oven on the upper level and are then sent on 1.5-m-wide chains through a cooling system. Packaging takes place down on the lower level. Here, 250-g cases are sealed in plastic individually or in packs of three and are then transported to where they are placed into larger boxes for shipping.

Rexroth's VarioFlow chain-conveyor system transports these three different-sized packages. United Biscuits uses three chain widths for this task: 80 mm for single packs, 160 mm for triple packs and 320 mm for boxes. "It was a big advantage that we could get all three widths from just one, modular system," explains Esselmann. He also notes a variety of additional benefits in terms of system planning and conveyor maintenance. "The entire system is made up of components that vary very little, which reduces the stock of spare parts," he says. "Plus, the chain links are just plugged together, so we don't need any special tools to open or modify a line."

A long-term employee at the cookie factory, Esselmann especially likes the open-system construction. "Although the cookies are already packaged before they reach the conveyor, there is always the chance that crumbs will fall on the conveyor," he relates. "Of course, this is all considered production waste, but it could quickly cause the chain to glide less smoothly."

VarioFlow does not have any profiles in the middle of the conveyor, which makes the system almost completely open and lets the crumbs fall through. That means the system stays clear of debris longer, requires less cleaning, and parts do not have to be replaced as often as with closed systems.

The conveyor's construction is not the only reason that VarioFlow is so long-lasting. Slide-profile mounting is also a contributing factor. Instead of more customary mounting with screws inserted from above, the symmetric sliding profiles in the VarioFlow system are fastened on the sides. "The benefits of this method are really obvious in our maintenance costs," says Esselmann, "since we can simply turn the profile around when it's worn out and continue to use the other side."

A longer service life is an important criterion for the innovative curve technology used in VarioFlow, and a patented ball bearing is integrated into all the curves. The resulting rolling friction lowers wear compared to normal sliding friction. Esselmann also recognizes another advantage with this bearing: "Common systems that have a curve wheel mean that we would have less room on the inside of the curve," he explains. "Our employees often came too close to the curve wheels, so we considered this solution critical in regard to safety. Safety problems like this don't even appear with VarioFlow." The integrated ball bearing also forms the technical basis to implement curves with larger radiuses.

Additionally, the project managers had to take into account the different-sized packages that would be conveyed on chains with various widths to a variety of packaging machines. The result is a system designed like a roller coaster in some sections. Besides shorter, curvy sections, United Biscuits also needed a very long, 40-m section. VarioFlow managed this lengthy distance with just one drive.

"This is the longest section we have here," says Esselmann. "We need it to reroute the packages to manual packaging workplaces in case there are any problems with the packaging machines. We can do this easily with VarioFlow, whereas other system manufacturers wanted to split up this section." The circulating chain is actually 80 m long, but thanks to the integrated bearing, it is particularly stable, even with five vertical curves.

Absolutely convinced by a perfectly running system, Esselmann is confident about future system changes. "This system is so flexible thanks to its special construction, chain links and easy assembly, that it won't be a problem to change the layout later if needed," he says. Until that time, 20 tons of cookies will continue to run on VarioFlow daily.

More information is available:

  • Bosch Rexroth Corp.— Linear Motion and Assembly Technologies,800/739-7684www.boschrexroth-us.com. Circle No. 216.

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