January 29, 2014

15 Min Read
A 'butter' way to palletize

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California Dairies, Inc. is the number-one dairy cooperative in California and the second largest in the U.S. It is owned by more than 650 California dairies that ship nearly 17 billion lb of milk annually to its five (soon to be six) processing plants. This equates to 45.5 million lb of milk/day, and that will soon increase to more than 50 million lb/day when the new Visalia, CA plant begins production. In addition to fluid milk processing, California Dairies and its subsidiary companies produce dry milk and butter-milk powder, butter and cheese and make a variety of vacuum-condensed and ultra-filtered dairy products.

California Dairies' plant in Turlock, CA, processes up to 5.7 million lb of milk/day and produces more than 110 million lb of butter/year, which is about 275,000 lb of butter/day. The plant produces more than 170 skus of butter in case sizes ranging from eight to 55 lb. To help keep so much product moving through its plants, the company is implementing more and more automation, including a new robotic-palletizing system. "The cows don't take time off for weekends or holidays, so the plant operates twenty four hours a day, seven days a week, year around," says Eric Snoke, vp of operations of both the Turlock and Los Banos, CA, plants.

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When butter is first made, it is soft, so custom end-of-arm tooling was developed specially to handle it.

Last year, Turlock automated the entire butter-line palletizing operation with a system that includes two four-axis EPL160 Expert Palletizing robots from Motoman, Inc. (www.motoman.com). Motoman also provided the overall systems integration, working in close partnership with Prime Conveyor, Inc. (www.primeconveyor.com), which supplied the conveyors and some of the controls work per Motoman's design. Snoke was discussing this project with several robot companies, when Doug Hill, president of Hill Packaging Systems (www.hillpackagingsystems.com) suggested he call Motoman. "It turned out that Motoman had the best system for us," says Snoke.

"Formerly, all of the palletizing was done manually, but at the rate we produce butter—three cases/min on eight lines for a total of 24 cases/min—this was backbreaking work," says Snoke. "When operators got tired, it would slow the packaging room down, which would slow down the line. We'd have to shut a few machines down until they could catch up. We knew that we needed to automate the operation to improve productivity and reduce costly worker compensation claims from back injuries."

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The paddle-type gripper is very gentle on the product, and it adjusts the air setting automatically for each type of box, so that each one gets just the right amount of pressure.

In addition to fully automating the packaging line, project goals included creating more consistent and stable loads and maximizing system throughput by eliminating downtime. "We calculated that the payback for the system would be two years or less, based on direct labor savings alone, and that does not take into account the reduction in workmen-compensation claims," Snoke says. "We haven't had any back injuries in that department since we put the robots in. Strains and back injuries, in general, are our biggest concerns. When lifting 55-pound boxes, one slip can cause you to throw your back out. Claims in the past were costly."

"We need eight or nine fewer direct-labor people per day now that we have the robots. Once we knew we were going to put in the robots, we let normal attrition reduce the headcount, and we covered with overtime. We didn't give anybody pink slips because of the robots. Our people like the robots a lot. This is a union shop, and the robot-operator jobs were bid. We had quite a bit of competition for the jobs to run these robots. Machine operators have a higher pay scale, so our people like that, too.

"We had no doubt that the robot system would work, but it was surprising how smoothly everything went in. Within a couple of days of bringing up the first line, the production crew's skepticism about getting it all to work was replaced with excitement about getting it all on line."

"The robot system has improved our ability to run in a consistent manner. Our packaging department has tried to push the limits, but the robots don't even break a sweat. We wanted to over-engineer the system by at least twenty percent. If every machine in the plant was running at maximum capacity, we could still have twenty percent robot capacity to do catch up. For example, if a line went down for some reason, such as a bad pallet, we always have a little capacity to do catchup."

Did you know:
The skinny on butterfat
Whole milk contains approximately 3.5 percent butterfat. The cream portion is separated and concentrated to 40 percent to 42 percent butterfat content. This cream is then churned into butter, which by definition, contains at least 80 percent butterfat. Salt and/or food coloring can be added to produce a multitude of varieties.
Source: California Dairies.

Adding robotic automation to the butter-palletizing line at Turlock was a challenging proposition. "When this project was first proposed, I thought it was crazy. With so many different products and the high level of complexity involved, I never thought it would be possible," says Keith Gomes, California Dairies' senior vp and COO. "But the success of this robotic-palletizing system at Turlock made a believer out of me, and it has had a major impact on how California Dairies will operate in the future.

"Traditionally, our industry has been fairly labor-intensive. We still have some jobs that cannot be automated, due to antiquated and outdated U.S. Deptpartment of Agriculture requirements and regulations. Washdown requirements, the wet environment and corrosive chemicals in our butter-production room are other barriers to automation. For example, the salt that is added to many types of butter is excessively corrosive to machinery. However, due to safety concerns, productivity requirements and reliability considerations, we will be trying to automate as much of our process as possible as we move forward. Both case packing and palletizing will be fully automated in our new Visalia plant."

The robots stack product onto four-way Grocery Manufacturers Assn. (www.gmabrands.com) wooden pallets in a multitude of different patterns. The robots also handle tier sheets and top sheets. Not all case patterns require tier sheets between layers. However, every pallet has a tier sheet on the bare pallet and a top sheet on the last layer. Only one major customer requires tier sheets on every layer.

"Pallet loads can be up to sixty-inches high, excluding the pallet. Stacks need to be tight, and labels need to be facing out whenever possible to facilitate bar-code reading," Snoke says. "Having the labels facing out is especially important for the display pallets used by the 'Big Box' stores."

Reliability is also extremely important. "Any downtime is incredibly problematic for our plant," says Snoke. "We have to keep running, and we have to have contingencies in place. One of our design criteria for the robot system was to have the ability to go back to manual palletizing in a dire emergency. We also wanted one party responsible for all aspects of the entire automation project, including the robots, controls, sortation systems, scanning systems and conveyors; all the way through to the printer that labels the stretch-wrapped pallets."

Butter has some unique properties that make palletizing it uniquely challenging. "When it is first made, butter is soft," Snoke explains. "Motoman developed custom end-of-arm tooling just for us. The paddle-type gripper is very gentle on the product. It adjusts the air setting automatically for each type of box, so each one gets just the right amount of pressure. We also sell large amounts of butter to 'Big Box' stores that use display cases that are open at the top. We needed a gripper with jaws that handle the boxes from the sides."

The paddle gripper is equipped with vacuum cups to assist in handling some products. When picking slipsheets, the robot gripper drops down onto a stack of slipsheets, and arms rotate out of its sides. After it picks up the slipsheet and drops it off, the arms fold back up, and the robot goes back to palletizing product. "It is a very active system, particularly when we are running all eight lines and the robots don't have to stop and wait for product to accumulate. They are fascinating to watch. We sometimes have to shoo people away, because they like to stand around and watch everything work," Snoke continues.

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The robots stack product onto four-way wooden pallets in a multitude of different patterns. The robots also handle tier sheets and top sheets.

Cases of product from up to eight production lines are combined onto two trunk lines that convey the cases to top and bottom flap-detection stations. Bar-code scanners at these stations validate the bar code's readability and identify the case's assigned conveyor-lane destination prior to flap detection.

Cases that do not pass due to unreadable bar codes or are unglued or have bad flaps are rejected down a manual line, keeping problem cases within the cold room. Cases that pass the checkpoints travel up an inclined belt and continue overhead through the wall that separates the cold box from the palletizing room. Cases then travel down a decline belt and are transferred onto a belt-sortation system. They make a 180-deg turn, after which another bar-code scanner again reads which of the eight downline conveyors used to queue product for robotic pickup has been designated as the destination for that particular case.

If the bar code on a particular case is not readable or its designated downline conveyor is full, the case is directed onto a recirculation conveyor. Cases on this conveyor are accumulated, are reintroduced into the sortation process and then are either directed to the previously full down-line conveyor or diverted onto the manual "noread" line.

A Motoman robot at Aliment Putter's Food,Inc., Sainte-Sophie, Quebec, runs up to 12,000 cases of pickles per day, each weighing up to 20 lb. Read about it at www.packagingdigest.com/ info/putters

Normally, a case travels to its designated downline accumulation conveyor. Each of the two Motoman robots services four of these infeed accumulation conveyors, which are equipped with case-crowding mechanisms and bump-turn devices. Once enough cases of a particular sku have accumulated for a pick cycle, the system signals the appropriate robot that product is present. As soon as the robot is available, it moves to that line and starts palletizing the load according to the pre-programmed stacking pattern.

The robot generally grasps two cases per pick cycle. The custom paddle-style gripper is designed with two separate zones, providing an asynchronous placement capability. For example, the robot could be programmed to pick up two cases (one in each zone), and then release the case facing in one direction before reorienting and releasing the remaining case. "Right now, though, cycle times are such that we just have the robot pick up a single case and place it individually," Snoke says.

The robot palletizes cases of product onto one of four designated pallet-load/build conveyors and also adds the slipsheets and tier sheets from dunnage carts as required. These dunnage carts are loaded by an operator and locked into place within the palletizing cell. Spare dunnage carts allow the operator to have the appropriate stack of sheets available, reducing downtime during the replenishment process.

A common dual conveyor-bed transfer-car (T-Car) system shuttles empty pallets, singulated from an automatic pallet dispenser, into the robot-palletizing cell. Once the robot loads the pallets, the T-Car system transports full pallets to the stretch-wrapper infeed conveyor that leads to the Model S1501 stretch wrapper from Lantech.com, LLC (www.lantech.com). The stretch-wrapped pallets are automatically labeled with multiple copies listing the contents, and are then conveyed back through the wall into the cold box. There, loads accumulate and are removed by forklift truck for shipment or storage. Whenever a load is moved, a portion of the label is torn off. These ticket labels provide a simple way to track the movement of each pallet. One or two are always left on the load, so the customer has a receipt. The T-Cars, conveyors and automated pallet dispenser were supplied by Prime Conveyor, Inc. Hill Packaging Systems installed the robots, as well as all of the equipment supplied by Prime Conveyor. Industrial Electric Co., (www.i-e-c.net) did the electrical and control wiring for this project.

System controls include a two-door control panel in the cold box and a three-door panel in the palletizing room containing the Allen-Bradley CompactLogix PLC from Rockwell Automation (www.rockwell.com). Two Motoman MotoHMIs(TM) provide operator interfaces in the rooms. Each HMI includes an industrial PC running RSView ME software on the 15-in. color touchscreens. The overall system utilizes DeviceNet as the communication protocol between devices, as well as for communication with the two Motoman NX100 robot controllers. The MotoHMIs contain an Ethernet interface with the California Dairies' server that allows the introduction of new products as well as tracks the status of the system.

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Two robotic palletizers handle more than 170 skus of butter in case sizes ranging from eight to 55 lb.

Motoman also provided all cell guarding, including wire safety fencing, four dunnage access gates with positive-break safety switches, two light curtains separating the T-Car from each of the two robot cells and one set of self-muted light curtains at the stretch-wrapper infeed conveyor. Dual-channel safety hardware for access gates and light curtains meets the American National Standards Institute/Robotic Industries Assn. R15.06-1999 safety standard.

"Every 24 to 30 hours the production room goes down for a cleanup that includes a complete wash of the whole room," Snoke says. During that time, the robot-palletizing room gets swept and everything gets cleaned up and put away, Turlock is a shielded plant, which means that we have a resident USDA inspector. The production room is always under close USDA scrutiny, and the robot room is also inspected regularly."

California Dairies is very serious about bio-security and lot traceability. "The robot system allows us to track product by time and date stamp, so we can trace the production of each lot and sub-lot in great detail. Each operator has a code, so we can tell who was running the machinery at any given time," Snoke explains. "We actually do six mock recalls a year, which involve tracing back through every aspect of production—from where the lot originated, and where it was sent, all the way up through the distributor. All products are marked 'Hold and Ship.' The microbe count must come back within specifications before the butter can be shipped.

"I've been involved in building entire plants from the ground up and have been involved in a lot of automation projects, but I've enjoyed this one more than any I've ever done. I'm as proud of it as I've been of any installation. We work as a team here at California Dairies, so it was important for us to have all areas of the plant involved in the project. For example, Glen Dortch, our warehouse manager, put together all the information Motoman needed on the multitude of different boxes the robot system needs to handle. Tom Baldwin, our butter-production manager, provided critical in-formation about product consistencies, packaging, etc., that Motoman needed for gripper and system design. Jon Sylvia, our plant-maintenance manager, was directly in charge of the system installation. John Bos, plant manager, was key to getting workforce buy-in and in streamlining all of the organizational elements.

"Motoman is the most professional group we've ever worked with. They really impressed us right from the start, when they sent a group of eight extremely talented and dedicated people here to investigate every single avenue of the project. Right off the bat, we got a good feeling about what we could expect from them.

"Every aspect of the project, from concept through installation, programming and training, went extremely well, and we've been incredibly happy. Motoman did the initial robot programming and still provides support whenever we need it. For example, Motoman's regional support specialist has been invaluable in super-fine tuning the programs. If we need something, we just call, and he's right there."

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Each of the two robots services four infeed-accumulation conveyors, which are equipped with case-crowding mechanisms and bump-turn devices.

The plant is looking ahead to future automation projects. "We're considering replacing an existing, non-Motoman four-axis robot used to palletize bags of powdered milk, with a new Motoman palletizing robot that is smarter and much more user-friendly," Snoke says. "Additionally, we're talking about things that we're trying to automate at all of our facilities. Our new Visalia plant will be the most automated plant in our system. It will also be a bulk butter/powder plant and undoubtedly will use robots. Anywhere in the process where people potentially could get hurt, we're looking at using robots and automation."

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