In-line blowing and filling of refrigerated flavored milk drinks into single-serve PET bottles is taken to a whole new level of automation at Mueller Sachsen GmbH in Leppersdorf, Germany. Just five operators are required to run two lines capable of in-line blowing and filling of PET bottles at a combined speed of 1,200 bottles/min.
Bottle sizes include 330-, 400-, 500-, and 750-mL (11.6-, 13.53-, 16.91-, and 25.36-oz). When all the different flavors are factored in, the number of SKUs involved is about 90. Faced with so much variety—driven, of course, by widely varying retailer preferences—changeover has to be optimized, and indeed it is. Changeover that includes a new bottle size requires about 3 hours, as blow molds have to be changed. But when going to a new flavor or label or a different bottle-count in a tray, which occurs far more frequently than a change in bottle size, changeover takes about 20 minutes. That compares to the two hours or so typically required on lines that are not so cleverly integrated. Even more impressive is that one of the lines is able to draw product from four different tanks and fill bottles in, for example, a chocolate, vanilla, strawberry, banana sequence. The different-flavored bottles are then united in equal ratios in a corrugated tray in quantities of 8, 12, or 24.
The secret to all this flexible automation is that production orders flow automatically from the firm’s Enterprise Resource Planning (ERP) system to a recently developed automated order system and thence out to packaging machines on three different floors of this sprawling and impressive facility. The ERP system comes from SAP (www.sap.com) and the automated order system, called Line Management System (LMS), comes from Krones (www.krones.com). Krones also supplied most of the packaging machines in the two lines, with the exception of two tray packers from Schubert (www.ckungsmaschinen.de), two palletizers from A+F Automation (www.afautomation.com), and a pallet stretch wrapper from Haloila (www.haloila.com). Krones was also responsible for line integration of the entire package. Mueller was the first to implement Krones’ LMS solution, and Mueller’s lines represent the culmination of more than three years’ work. The Mueller installation remains among the most sophisticated automated order systems in the world of packaging.
It should be noted that this kind of Information Technology is designed specifically for packaging lines where changeovers are common. In such an environment, it pays big dividends. This is especially true at Mueller, because not only is changeover frequent but the packaging lines are spread across three floors. Blowing and filling is done on the ground floor, labeling and tray packing is done on the third floor, and palletizing/stretchwrapping is done on the second floor.
“The LMS helps a lot,” says Mueller project engineer Hagen Riedel. “We gain tremendous visibility into what machines are doing throughout both lines, even though the machines sit on three different floors.” Without such visibility, he adds, 20-minute changeovers would not be possible.
At the touchscreen of each packaging machine, says Riedel, the operator is informed what the equipment must do for the current order and the following one, too. He knows the planned number of containers in each batch, and he knows what preform, cap, label, and corrugated tray need to be made available so he can have them ready before they’re even needed. With the press of a button, packaging materials that are going to be needed for the next order are automatically delivered by the warehouse management system.
Comparison of old and new
In a more conventional scheme, there’s a tendency to consider each machine in the line as an individual entity. When changing over to a different SKU, in most cases the entire line is emptied before the next order commences, following any necessary make-ready adjustments. The requirements for the operator include ordering the raw materials and supplies in good time, manually selecting the product and parameters at the machines, and starting up the line. This laundry list of tasks demands a lot from the operators, and the difficulty of executing these tasks is magnified when product diversity is as great as it is at Mueller and when filling and secondary packaging don’t even take place on the same floor.
Thanks to Krones’ LMS, the lines at Mueller operate in anything but a conventional scheme. They’re controlled as tightly integrated systems running sequential batches in an optimized manner. They obtain all production-relevant information not from shift managers wielding clip boards or from operators entering it at a touch screen panel. Instead, it comes down from the ERP system. This includes all requisite data for tracking, such as sell-by date, filling time, and filling valve assignment. Operators on the line see two batches at a time: the current one and the next one. This enables them to perform forward planning at their machines. “Mueller wanted to take automation as far as they could, even to the point of having orders transmitted automatically from the customer’s ERP to the Mueller ERP and right on out to the packaging lines on the plant floor,” says Holger Bissbort, Information Technology project manager at Krones.
What makes Mueller’s installation significant from a controls and integration standpoint is its ability to take data from the top-level business communications protocol that is common to ERP systems and send it down to the plant floor environment where a manufacturing communications protocol is more common. An XML (Extensible Markup Language) interface is the key, says Bissbort.
“This interface makes sure that the information coming from the ERP is accessible to our Line Management System’s main PLC,” says Bissbort. “From that PLC, the information goes out to individual packaging machine PLCs via an industrial Ethernet connection.”
Why three floors?
The decision to spread the two packaging lines across three floors was dictated by the need for accumulation space and by the sheer number of packaging machines that make up the lines. Most of the equipment is on the first and third floor; on each of these floors, the footprint of the packaging equipment is about 98’ x 262’. At least 21 major pieces of machinery are involved, including two blow molders, two sterilizing/rinsing/filling/capping blocks, two ink-jet coders, six sleeve labelers, five wraparound labelers, two tray packers, and two palletizers.
Line 1 is by far the most complex and dynamic of the two lines. Bottles are blown on a Krones Contiform S24 and then air conveyed some 170 m (558’) to the enclosed and overpressured aseptic chamber in which sits the Krones Pet-Asept sterilizing/filling/capping system.
“We need a three-minute buffer space in which bottles can accumulate,” says Riedel in explaining why so much air conveying is built into the line.
The sterilize/fill/cap block has a lot going on inside its enclosed chamber walls. In addition to being able to fill four flavors at once, the filler operates aseptically. Unlike most aseptic filling operations, shelf stability is not the goal. What Mueller wants to deliver is the best-tasting refrigerated milk-based drink that filling technology will allow. Relying on commercially sterile filling conditions in an aseptic chamber is one way it does that. The first step inside the overpressurized aseptic chamber is sterilization with peracetic acid and steam, done on two rotary carousels with 60 stations each. Starwheels hand bottles off to a second rotary carousel, this one having 100 stations, which rinses bottles with sterile water then sterile air. Last but not least is filling, done on a 60-nozzle “rainbow” filler.
The “rainbow” designation refers to the filler’s ability to meet retailers’ demands for multiflavored multipacks by drawing from four different tanks and filling four flavors at once. Nozzles 1, 2, 3, and 4 each fills a PET bottle with a different flavor, with nozzle 5 reverting back to the flavor filled by nozzle 1.
UV code on caps
Exiting the capping station, bottles pass beneath a Domino Amjet (www.dominoamjet.com) ink-jet coder that uses UV inks to put a symbol on the top of each cap. (More on this later.) Now the bottles are conveyed to the third floor for labeling and secondary packaging. Some bottle types require a wraparound label while others get a full-body shrink label. So both styles of labeling machines stand ready on the third floor. And because Mueller is “rainbow filling,” not two but eight labelers are needed—four Contiroll wraparound labelers and four Sleevematic shrink sleeve labelers, all from Krones. Included in each production order that comes down from the ERP system is the information that “tells” the bottles to which labeler type they should proceed: wraparound or sleeve.
As for the symbol printed in UV ink on each cap, it performs its function just ahead of labeling. A Krones Checkmat scanning device reads the symbol and then, based on what it sees, diverts the bottle down one of four lanes, each leading to the labeler that will apply the right-flavored label: chocolate, vanilla, strawberry, or banana.
Next is tray packing on a Schubert system that’s 10 m (33’) long and incorporates a total of 13 robots. It erects paperboard trays from flat blanks and sends them through four loading stations. At each of these stations, incoming single-laned bottles are fed by a starwheel into a carrier that is conveyed a short distance to a position from which a robotic picker can remove them and place them in another carrier. From this second carrier, a second robotic head picks the bottles and puts them in a tray.
Capable of 720 bottles/min, the Schubert system can produce 8-count trays in a 2x4 pattern, 12-count trays in a 4x3 pattern, or 24-count trays in a 6x4 pattern. The system also has an optional feature that applies clip-on paperboard handles to groups of either two or four bottles per group.
When a tray has its full complement of bottles 8-, 12-, or 24-count trays can all be produced—the tray exits and is conveyed to a spiral conveyor that takes it down to the second floor and a palletizer from A&F Automation. Bringing the line to a close is a Haloila stretch wrapper. Mueller management is pleased with the efficiency it has gained from the implementation of this higher-order packaging machinery control system. “Faster changeovers, centralized operator control, and more effective operator routines are among the benefits we’ve gained,” says Riedel.