Morningstar milks ESL, aseptic linesMorningstar milks ESL, aseptic lines

The process of aseptically packaging low-acid dairy products in plastic bottles is on the horizon in the U.S. Morningstar Foods will install the first aseptic filler in the U.S. in its plant in Mt. Crawford, VA, this summer. A number of companies, including parent Dean Foods, H.P. Hood and WestFarm Foods, have installed equipment in the last few years to produce extended-shelf-life products in plastic bottles; Morningstar itself installed a new ESL line last fall. However, when approved by the FDA, its aseptic line will be a first.

"This is a step in a new direction for Morningstar. We're confident we will be the first to produce aseptic dairy products in plastic bottles," says president and COO Bing Graffunder. One thing is certain: These lines are not cheap. "Each line costs twelve to fourteen million dollars and will produce fifity-million dollars plus worth of product a year," says Graffunder.

Morningstar Foods, Inc. is a subsidiary of the new Dean Foods Corp. It has 15 manufacturing plants distributed across the U.S. Last August, Morningstar Foods and Hershey Foods Corp. announced a strategic alliance in which Morningstar will be the first company to manufacture, sell and distribute Hershey brand name dairy products nationally. Initially introducing the products in paperboard gabletop packaging, Morningstar began producing the Hershey beverages in 14-oz high-density polyethylene bottles at Mt. Crawford this fall. In addition, a licensing agreement between Morningstar and The Procter & Gamble Co. has resulted in the production at Mt. Crawford of Folgers Jakada chilled coffee drink made from Mountain Grown® Folgers coffee and lowfat milk in 10.5-oz HDPE bottles.

The Mt. Crawford plant was a full-line dairy for years, but Morningstar moved most of this equipment to other facilities last fall so it could focus on ESL and aseptic products. As part of this conversion, Morningstar installed a new aseptic processing system to produce sterile milk products. The 50,000-lb/hr system includes a triple-tube processor that heats the product with superheated water to 280 deg F, with a minimum two-second hold time, followed by cooling to 45 deg F, and a two-stage aseptic homogenizer. Product is stored in aseptic silos. All major processing equipment is supplied by Stork Food & Dairy Systems, Inc.

Stork is also the supplier of the front-end equipment for both the operating ESL line and the new aseptic-capable line, including the blow molders and fillers. "We chose Stork because they are the furthest along the curve in this technology," says Graffunder.

One element in this choice is FDA acceptance. Says Willis Brown, Morningstar corporate engineer, "The laminar airflow in the linear filler makes it much easier to prove sterility compared to the turbulent airflow in a rotary filler. We installed the ESL filler as a prototype for the aseptic machine, and it has lived up to our expectations. I'm very pleased with it; it has given us invaluable experience that we can apply to the aseptic operation."

Another factor in this selection was Asep-Tech, Springfield, MO, a joint venture of Stork and Dairy Farmers of America. Asep-Tech was created in July 1999 to further aseptic processing and packaging technology in the U.S. It includes a pilot plant with a Stork linear filler, similar to the unit at Morningstar, and associated equipment, where operating protocols can be developed. Also part of the team is Dover Brooks Assoc., Chester, NY, which is the "process authority" for this project.

Two blow molders
The ESL packaging operation starts with two Stork clean 15-mold rotary extrusion blow molders. These machines incorporate HEPA filters to produce sterile air for blow and parison support, as well as the blowing air to produce sterile bottles with closed tops. Rated at 110 bottles/min each, the units operate for extended periods to accumulate bottles for the 300 bottle/min packaging line.

Both the 14-oz Hershey bottles and the 10.5-oz Jakada bottles weigh about 23 grams each. They are a three-layer construction with virgin HDPE on the inside and outside, and a middle layer comprised of regrind HDPE and carbon black to block light transmission into the product. This multilayer construction requires two extruders, one for the virgin HDPE and the other for the carbon black mixture, feeding a coextrusion head for the extrusion of the parisons for the bottles.

The finished, closed bottles are pneumatically conveyed to three silos with a capacity of 30,000 bottles each located on the second floor. Ideally, bottles should remain in the silos for at least four hours to cure before use. For this reason, silos are emptied on a first-in/first-out basis. Changing bottle size takes four to five hours. The blow molder incorporates a proprietary menu-driven Stork PC for control.

Bottles discharge from the silo and are delivered to a Posimat centrifugal unscrambler that stands them upright on the conveyor. Bottles drop into pockets on the periphery of the machine and then drop through funnels onto the discharge conveyor. Due to the special shape of the pockets, bottles always appear in an upright position.

One advantage of the Posimat is that bottles move by their own weight or with the assistance of air jets. There are no mechanical parts applying pressure that could damage the surface of the bottles. An electronic system detects oversized bottles and activates a compressed air jet that ejects the bottle out of the machine.

Bottles are conveyed to a machine that cuts the tops off and then to an 18-head rotary leak tester supplied by Wilco AG that pressurizes them with air. If the air pressure in the bottle fails to reach a minimum pressure, or if the air pressure decreases by a set amount between the beginning and end of the test, the bottle is classified as a "leaker" and is rejected.

When the aseptic filler is installed, the plant will also install two more blow molders, a top cutter and a leak tester, and three more bottle silos.

Hydrogen peroxide sterilization
After leak testing, bottles are conveyed to the Stork 12-lane linear filler. This linear design is unique for this application. All other bottle fillers in the dairy market utilize a rotary configuration.

When the bottles reach the filler infeed, 12 bottles at a time are deposited onto 12 conveyors that deliver them onto the filler's transfer conveyor. These conveyors, which run faster than the filler, provide accumulation ahead of the filler. Sensors, located at strategic points, detect when each conveyor is full and when more bottles are needed, and start and stop placing bottles on the conveyors accordingly. The filler is controlled by an Allen-Bradley PLC with an operator interface.

Bottles drop off the end of the feed conveyors to stand up in carrier slats affixed to the transfer conveyor that runs through the filler. Sensors detect missing bottles in any lanes and inhibit filling and closing operations for those locations. The first operation in the filler is to inject vaporized, 35 percent hydrogen peroxide solution at 280 deg F into the inside and around the outside of the bottles. This is done three times in consecutive stations. The bottles next pass beneath jets of superhot air to ensure removal of all hydrogen peroxide.

The Morningstar machine has two filling stations on each lane, each dispensing about half of the required amount of product. Filling in two steps minimizes cycle time, which is currently 2.4 seconds per index. Product is delivered from a pressurized balance-tank through individual magnetic flow meters for each fill nozzle. Each fill nozzle incorporates two valves in series. The first is an on/off, while the second is a flow regulating valve that admits product to the bottle slowly initially, progresses to full flow, and then tapers off at the end of the cycle. To minimize dripping, the nozzles have a series of interior concentric rings at their outlets that provide a strong capillary action that retains product.

After filling, the bottles are conveyed through the top-sealing station, where laminated foil lids are conduction-sealed to the bottles. Supplied by Label Makers, Inc., the lids consist of a 1.25-mil proprietary plastic sealant film laminated to a 2-mil foil. The lids are supplied on a roll and are punched out by a machine supplied by Fords Packaging Systems. The punch-out machine is located on a platform above the filler, and the lids are conveyed down individual tracks to the application section. For this ESL application, the lids pass through an ultraviolet light sterilization section. On the aseptic-capable machine to be installed next summer, the lids will be sterilized by vaporized hydrogen peroxide just like the bottles.

At the filler discharge, a reciprocating arm with grippers picks two rows of bottles out of the slats, swings over, and places them in two rows on the takeaway conveyor. Groups of 12 bottles (from the 12 lanes) are kept separate on the conveyor. The bottles pass a Videojet ink-jet printer from Marconi Data Systems that prints the product code, lane number, date and fill time on the bottoms. The computer keeps track of each bottle while it is in the filler and after it discharges. If a bottle was missing from a particular spot in a lane, there will be no bottle in that group with that lane code.

Both bottles currently being run have the same diameter, so they fit in the same slats in the transfer conveyors. However, the bottles are different heights, so the filler bed is raised and lowered by hand-cranks on the side of the machine. Bottles are deposited in every-other slat when they enter the filler, so if different bottle diameters are being run, different size slats can be placed in the alternating spaces, and bottle placement controlled by the servo drive with the computer control.

The aseptic filler will operate identically, but will have enhancements to maintain sterility, says Brown. It will include HEPA filters to ensure sterile incoming air, and they will be treated with hot hydrogen peroxide vapor as part of the initial machine sterilization procedure. The foil lids will pass through a hydrogen peroxide sterilization chamber before they enter the machine. The aseptic-capable machine will also incorporate a servo drive controlled by the computer, rather than manual cranks, to change the fill height.

First in/first out bottle accumulation
After the bottles are printed, they are conveyed past a horizontal accumulation table and then are delivered in bulk to a Dynac 7000 two-tier spiral accumulator from Hartness International. The unit has 180 feet of usable conveyor surface that provides up to 15 minutes of accumulation. With an accumulating conveyor system that automatically responds to production line flow changes in real time, this unit provides first-in/first-out sequencing. Says Brown, "The key to filling line efficiency is to keep the filler running, and we've had very few occasions where we've had to stop the filler for downstream equipment stoppages."

Side-by-side 18-in.-wide infeed and outfeed conveyors in the Dynac operate independently in opposite directions and are mechanically linked by a package-transfer mechanism. Sensors on the conveyors monitor bottle flow and adjust the conveyor speeds accordingly.

The package-transfer mechanism, which is dubbed "the spider," moves up or down between the spiral conveyors (depending on the relative speeds of the two conveyors) and transfers bottles from infeed to outfeed conveyor as it moves. In the Morningstar unit, the transfer is done by a short vertical conveyor that diverts bottles from the infeed conveyor to the outfeed conveyor. When the outfeed conveyor is running slower than the infeed conveyor, the spider travels up the spiral and fills up more of the outfeed conveyor. Conversely, when the infeed conveyor is running slower, the faster-moving outfeed conveyor begins to empty, so the spider travels down the spiral as it transfers bottles. When infeed and outfeed conveyor speeds match, the spider remains in place, transferring product from one conveyor to the other.

Two sleeve labelers and cappers
Bottles are separated onto two conveyors after the accumulator and delivered to two American Fuji Seal sleeve labelers. Rated at 350 bottles/min each, either of these units could handle the entire output of the packaging line. However, the redundancy provides insurance in case of a malfunction. Plus, the plant plans to add a third labeler when it installs the new aseptic-capable line, at which time it will have one labeler dedicated to each line, plus the third unit for insurance for both lines. "I think American Fuji labelers are great," says Brown. "They're very untemperamental, and they just keep on running without stopping."

The shrink-sleeve labels, which are supplied on rolls by American Fuji Seal, are a heat-shrinkable, mono-axially oriented, high-shrink PVC film. They are rotogravure reverse-printed in seven to nine colors, depending on the product flavor. A proprietary formulated ultra-density silver metallic ink helps achieve the color objectives associated with the Hershey's brand.

The labels are pulled from the rolls and pass through an 8-ft-tall vertical accumulator to provide a reservoir of labels so the machine can keep running while a new roll is spliced onto the old one.

From the accumulator, the film travels over dancer rolls for tension and tracking control, and then past a printing station where a Marconi Videojet printer applies a product code vertically on the film. The film travels over a roller at the top of the machine and down into the application section. Rollers pull the film over a mandrel that opens it into a cylinder, and it is then cut into individual sleeves by four blades in a rotary cutter. A sensor detects the open area between individual sleeves and triggers the cutters.

Bottles are delivered to the labeler single-file and are metered into the machine by a feedscrew that establishes the proper pitch of the bottles. A photoeye triggers two rollers that fire the sleeve down onto the bottle as it passes below. A series of small rotating vertical brushes pushes the sleeve down against the conveyor to ensure that it will shrink all the way to the bottom of the bottle. Sensors detect bottles with missing labels, labels that are too high, and splices in the film, and actuate an air cylinder that pushes the bottles off the conveyor.

The bottles then enter a modular-design steam tunnel with individually controlled steam zones and multiple steam-nozzle types for optimum shrink results. Jets in the first zone are directed at the bottom of the bottle to shrink the label tightly and lock it in place. Following jets direct steam progressively higher on the bottle to shrink the film into the grooves, and finally onto the shoulder.

The flexible design of the machine allows quick changeovers to run a large variety of bottle shapes and sizes. Both bottles Morningstar is currently running are the same diameter so the only change is to screw an extension onto the forming mandrel. If a different bottle diameter is run, the mandrel and cutter assembly can be easily removed and replaced in a very short time. The labeler and shrink tunnel are computer-controlled, and all of the operating settings for each bottle, including steam flow in the tunnel, can be selected from a menu on the operator panel.

Bottles are conveyed to a Fowler/Zalkin 10-head rotary capper, where the overcaps are applied. The polypropylene Hershey caps, which are supplied by Phoenix Closures, are a non-standard 43-mm size, with a wide shoulder and threads that are significantly wider than the top opening, to give a "retro" look. The closures feature triple-lead threads that are easy to apply and minimize cocking during application.

From a floor hopper, the closures are transported up to a centrifugal sorter on the machine. The caps travel down a chute, and a finger at the bottom holds them back until a sensor detects a bottle. The cap is then released to a cap-transfer starwheel containing 10 pockets. This unit rotates and presents the cap to the chuck in the capping head, which picks up the cap and descends onto the bottle. The chuck turns until it reaches the set torque, at which time it releases the cap. If a bottle-pocket in the capper does not contain a bottle, the unit does not release a cap.

Stork was responsible for the integration of all of the equipment and also supplied the conveyors up to the sleeve labeler. Conveyors and accumulation tables after the labeler were supplied by the Garvey Corp.

Glue bottles to a paperboard pad Bottles from both labeling/capping operations are combined and are delivered to a Delkor Model 180 Spot-Pak system that glues them to paperboard pads. "The Spot-Pak is cost-effective and provides impactful, high-imagery packaging graphics. Another factor for us is that the bottles are strong enough for stacking without a case," says Brown.

The Spot-Pak system assembles and glues two 12-packs simultaneously. Bottles entering the unit are split into six lanes (three for each 12-pack). Sensors detect the presence of bottles, and when the proper backlog is assembled, a shuttling robotic pick-up head lowers and picks up 24 bottles (four bottles from each lane). At the same time, two paperboard base-pads are indexed forward from the pad magazines and pass under the adhesive application head. The bottles are then placed exactly on the two pads. The adhesive bonds the bottles instantly, ensuring package control throughout the shrinking operation.

The trays then pass through an Arpac Model 112 shrink wrapper that wraps film loosely around the tray and bottles, and then shrinks it tight in a steam tunnel. The Model 112 uses plain film from two rolls that is glued together around the package and then shrunk. However, the plant plans to add a single-roll wrapper that will use registered film to produce attractive packaging for multipacks.

The packages then pass a Diagraph PA/5000LT machine that prints a label and applies it to the package, after which they are hand-palletized.

More information is available:

Process authority: Dover Brooks Assoc., 845/469-4809. Circle No. 253.

Aseptic pilot plant: Asep-Tech USA LLC, 417/861-3013. Circle No. 254.

Blow molder, filler, inner-cap applicator, conveyors, system integration, processing equipment: Stork Food & Dairy Systems, Inc., 770/535-1875. Circle No. 255.

Unscranbler: Posimat, 305/854-4435. Circle No. 256.

Leak detector: Wilco AG, 41-56-618-4343. Circle No. 257.

Lid punchout machine: Fords Packaging Systems, 44(0)-1234-852365. Circle No. 258.

Foil lids: Label Makers, Inc., 262/947-3300. Circle No. 259.

Ink-jet printer: Marconi Data Systems, 630/860-7300. Circle No. 260.

Accumulator: Hartness International, Inc., 964/297-1200. Circle No. 261.

Sleeve labelers, labels: American Fuji Seal, 973/882-5600. Circle No. 262.

Capper: Fowler Products Co., 706/549-3300. Circle No. 263.

Closures: Phoenix Closures, 630/420-4750. Circle No. 264.

Conveyors: Garvey Corp., 609/561-2450. Circle No. 265.

Paperboard gluing: Delkor Systems, Inc., 763/783-0855. Circle No. 266

Shrink wrapper: Arpac LP, 847/678-9034. Circle No. 267.

Label print/apply: Diagraph Corp., 314/739-1221. Circle No. 268.