In the latest Krones capper for application of plastic threaded caps to plastic bottles, a new servo motor/drive technology from Elau adds flexibility, speeds changeover, and provides continuous tracking of performance data. It also reduces opportunities for contamination because it minimizes the number of mechanical components above the point where sterile caps are transferred onto aseptically filled containers. Krones is the first OEM to integrate the PacDrive™ SCL-055 servo motor/drive unit in a packaging machine.
Martina Wrede, a mechanical engineer at Krones, says the new breed of capper is uniquely suitable for cold aseptic filling, where contamination of any kind is especially problematic. Wrede also values the flexibility that comes when each capping station has its own servo motor/drive unit.
“If you need to switch to a different closure that happens to require a different torque, you make that change at a touch screen well outside of the aseptic chamber,” says Wrede. “With a more conventional capper, you’d have to open the aseptic chamber, close the chamber, and then re-sterilize the chamber before capping could resume.”
So what has precluded, prior to this application, the use of servo motor/drive units dedicated to individual capping stations on rotary cappers like this? Space requirements were a key impediment. The specially designed trapezoidal, as opposed to rectangular, shape of the SLC-055 makes it possible to mount 20 of these compact units on a rotary-style capper like the one built by Krones. And because drive and motor are combined in a single unit, gone is the complexity of running motor cables from individual servo motors on a rotating table back to servo drives located in a control cabinet.
Krones engineers also leveraged the data collection and recording capabilities that come with Elau’s PacDrive controller. With a similar machine that didn’t have a servo/motor drive unit on each capping station, “You’d need an operator to remove bottles at random from the capper every few hours to measure torque and record it,” says Wrede. Not so with this capper. Torque data is collected as a matter of course by the controller and is available whenever someone wants to see it.