In intralogistics, there is a wide range of solutions to satisfy the different requirements for warehouse systems. If several pallets of a product need to be stored neatly and unmixed in a limited area, and if permanent availability also plays a crucial role, a pallet flow rack is often the best solution. Bito Lagertechnik has worked with ebm-papst to develop a new kind of racking system. With PROflow active, drive rollers nudge the pallets just enough to get them moving – and slow them down when needed.
The limits of gravity
“With PROflow active, we’ve taken a step beyond our standard product range as far as pallet flow racks are concerned,” says Alexander Lang, product manager at Bito. Natural forces are usually called on to get things moving in such systems; pallets in flow racks are usually driven by gravity. They glide along an inclined plane with a slope of four percent from the loading to the unloading side – a proven technique, but one that reaches its limits in some situations.
Depending on what loads are being conveyed on the runways, problems can arise when pallets don’t start moving or when they simply stop. That reduces product availability. In addition, newly loaded pallets can slide down the runway into ones that are stuck. The resulting collisions can damage sensitive goods. A braking system is installed at the unloading side of conventional flow racks to prevent the following pallets from pressing on the front pallet when a forklift removes it. But depending on how it is operated, this mechanical assembly can cause problems such as jammed pallets.
Benefits of drive rollers
So Bito chose to use drive rollers instead. They push the pallets along, prevent unwanted stops and can also slow them down. On the runway, they can keep pallets with sensitive goods apart so they move completely free of contact. There is no longer any need for the braking system; when the forklift operator removes a pallet, the rollers move the pallets along the runway only after a predefined interval.
Besides increasing availability and protecting the goods, PROflow active also makes it possible to cut the runway’s slope in half. That means more pallets can be stored in the same space. “There is no other flow rack on the market that works with a slope of only two percent,” says Lang.
System solution, ready to install
The drive unit is the result of a joint development effort by Bito and ebm-papst. “Besides issues like size and power, one of Bito’s main questions was how such a complex system could be integrated in a roller in the flow rack,” recalls Matthias Trenz, Market Manager Industrial Drive Technology at ebm-papst. After many discussions, experiments and test phases, the drive solution is available as a ready-to-install cartridge – a plug & play system including a BLDC motor with electronics, brake and transmission, and the drive housing with roller cap and external cabling.
The drive motor is the ECI 63.20 K4, a brushless 180-watt internal rotor motor with an integrated K4 controller and a brake module. “The system had to work without a control cabinet in every runway to keep the amount of cabling to a minimum,” says Trenz. The system’s intelligence is distributed in every roller, so the rack system can be expanded or reduced as needed.
The drive motor has a two-stage Performax® planetary gear system with a rugged combination of plastic gears in the first stage and hardened steel gears in the second stage. In numerous tests, Bito and ebm-papst determined the torque and gear reduction required for the application. Ultimately, they settled on a high gear reduction of 102:1 for the optimum design.
The drive system is integrated in a housing; the cable is routed out of the roller cap. “We adopted Bito’s roller contour with 80 millimeter diameter for the roller cap so it can simply be slipped over it and clamped in place,” explains Trenz.
The partners also developed a compression coupling that is placed on the drive shaft to provide force transmission in the rollers. “The integrated drive system makes it very easy for us to install,” says Alexander Lang enthusiastically. The complete rollers are installed in the side walls of the runway.
“We worked extensively with the entire system for PROflow active for a year and a half,” says Lang, “because we really wanted to get involved in this new technology.” Its many successful validations are proof of its high quality. The effort is worth it, because the flow rack has a lot of potential. It can be used with various packaging and pallet types wherever sensitive goods need to be handled. The drives also prevent unwanted rocking during transport along the runway. “There’s no wobbling at all,” says Lang happily.