Upgrading a packaging operation with an automated bagger and robotic palletizer

A corn mill automates its bagging and palletizing line to improve production rates and decrease labor costs. Agricor Inc., Marion, IN, has been producing dry milled corn products since 1983. The company buys yellow corn from local farmers and grain elevators and mills it into degerminated corn grits, cornmeal, and corn flour. The products are packaged in bulk containers, such as bulk bags and hopper cars or 50- and 100-pound bags, and shipped to various US, Canadian, and international companies for use in food and industrial products. In the past, the company manually bagged and palletized the small bags. However, this method was inefficient, labor-intensive, and dusty, so the company decided to automate it.

Packaging Different Products

The company annually mills more than five million bushels of corn into corn grits, cornmeal, and corn flour. Because each product has a different bulk density and volume, the company uses three sizes of 100-pound bags and two sizes of 50-pound bags when bagging the various products.

Experiencing Bagging and Palletizing Problems

In the past, manually bagging and palletizing the products required four to six operators per shift, depending on the bag size being filled. One operator moved filled bags through a bag sealer, one to three operators stacked the filled bags on a pallet, one operator cleaned up any spillage and dust and refilled the bagger’s empty-bag magazine, and one operator drove a fork truck that moved full pallets to the warehouse.

When manually bagging and palletizing the various products, the company was able to produce 100-pound regular and cornmeal bags at 5 bags per minute, 100-pound flour bags at 3 bags per minute, 50-pound regular bags at 7 bags per minute, and 50-pound flour bags at 4 bags per minute. However, to maintain this production level and continue meeting customer demand, the company typically had to operate three shifts a day, six days a week, and hire up to two temporary employees per shift.

“We basically threw labor at the production problem,” says Jack Jones, Agricor warehouse and packaging supervisor. “For the 100-pound bags, we had one operator using a machine that assisted with the pallet stacking. For the fifty-pound bags, we needed two operators manually stacking them, and in busier packing periods we’d use three operators. To minimize the risk associated with manually handling so many bags, during each shift we routinely rotated the operators through the bagging and palletizing line’s operating stations. Looking back, we were very fortunate not to have had any ergonomic issues while manually handling so many bags, but it was always something we worried about.”

According to Steve Wickes, Agricor President, another problem was that “the bagger’s filling accuracy varied quite a bit, with the corn grits and cornmeal varying about one pound from the set bag weight and the flour varying considerably more than that. And since we typically erred on the side of overfilling the bags, we were losing product with nearly every bag we filled, which cut into our profit margin.”

The company needed to improve its bagging and palletizing operations, especially if it wanted to continue increasing its customer base. “We couldn’t increase production because we were already operating the packaging line at full capacity, so we were basically at a standstill,” says Wickes. “We also needed to improve bag-filling accuracy to minimize product loss, and we needed to decrease the number of operators and time required to bag and palletize the products. So we decided to completely automate the packaging line and upgrade the metal detection equipment to better guarantee product purity.”

Looking at Automation Options

Wickes and Jones contacted various bagging and palletizing equipment suppliers. “We told them we were looking for an automated bagger, bag sealer, and robotic palletizer that could handle all three products without requiring time-consuming adjustments between product runs,” says Jones. “We also told them that the packaging line’s equipment would be installed in an area with limited floor space and that they would probably have to custom-design the conveying line and equipment layout to fit everything in that small area. Additionally, removing the old equipment and installing the new had to happen within a very short timeframe because we had to maintain our production schedule. Basically, the supplier only had two consecutive weekends, or about ninety-six hours, to install the entire packaging line.”

Among the competitive bids, one stood out after Wickes and Jones compared the various elements of each proposal. “We looked at each supplier’s installation and equipment costs, equipment quality and system design, and project management philosophy and follow-up service and concluded that only one supplier had the package best suited for our application and budget,” says Wickes. “Before we made our final decision, we sent all three products to the supplier’s test facility for testing, and we visited one of their installations in Toronto and talked with another one of their customers in Saskatchewan. The tests showed that their bagger could easily handle our three products, and we only received positive feedback from the customers we talked with, so we decided to purchase one automated open-mouth bagger with an automatic bag sealer and one programmable robotic palletizer from the supplier.”

The supplier, Premier Tech's Industrial Equipment Group (IEG), Rivière-du-Loup, Quebec, designs and manufactures customized and automated packaging, palletizing, dosing, and stretch wrapping equipment and systems for handling dry bulk solids.

The Automated Bagger and Robotic Palletizing Cell

The PTK-1700 Series high-speed bagger bags powdered or granular materials—including minerals, chemicals, food, and animal feed—into open-mouth paper, PE, and woven PP bags at rates up to 25 bags per minute, depending on the bag size and material. The bagger has all stainless steel product contact surfaces and provides dust-free bagging with total bag control for hygienic and food-grade applications. It also provides quick and reliable transfer of filled bags to the automated bag-sealing system.

The bagger’s PLC has a user-friendly touch screen operator interface that allows easy troubleshooting and error code reading, and its self-diagnostic software has emergency stop interlocks to ensure operator safety during operation. The bagger’s integrated scale-control system consistently provides accurate material weighments, and its multiple-stack bag magazine allows fast reloading and quick bag-size changeovers.

The AR-200 Series robotic palletizing cell can simultaneously gather bags from up to four different product lines and palletize up to 28 bags per minute, depending on bag characteristics, pallet height, layout configuration, and other factors. For Agricor’s application, the supplier configured the palletizer to gather bags from only one product line because of the limited floor space.

A PLC with a user-friendly operator interface is located on the robot controller and shows 3D equipment and layout drawings for easy operation in manual mode. The interface also shows stored recipes that an operator can quickly access for changing the bag size and palletizing pattern.

The automated palletizer automatically places empty pallets and slip sheets, and its robotic arm has a finger gripper equipped with an automatic bag-width adjustment system. This allows it to easily handle bag sizes from 9 to 23 inches wide, 13 to 39 inches long, and 1.5 to 6 inches thick, and bag weights up to 176 pounds. The palletizing system’s PLC uses collision-guard software to prevent accidental damage to the robotic arm’s gripper and other equipment.

Installing the Packaging Equipment

The company hired a local millwright (Industrial Maintenance Specialists) and electrical contractor (Rex Collins Electric) to install the new equipment. On Friday night, February 15, 2008, the millwright crew, along with the supplier’s engineers and Agricor’s operators, began removing the old bagger from the plant. “We took out the old bagger and put in the new one,” says Jones, “and the next weekend we installed the robotic palletizer, conveyors, and the other equipment. We met our installation timetable both weekends and were up and bagging product each Sunday night. It was an impressive performance because everything had to be installed right on the money; we had no space to spare. In fact, there’s only three inches of space between the equipment and one of the walls; that’s how tight the whole system is.”

The company now requires only three operators per shift to run the packaging line: one watches over all of the machinery, one cleans, and one drives the fork truck. Currently, the company is bagging 100-pound regular and cornmeal bags at a rate of 9 to 11 bags per minute, 100-pound flour bags at 7 to 9 bags per minute, 50-pound regular bags at 15 bags per minute, and 50-pound flour bags at 8 to 10 bags per minute.

Improving the Company’s Packaging Operations

Since installing the new automated bagging and palletizing line, the company has significantly reduced its operating and labor costs. “The new packaging line bags the products so fast we only have to operate two shifts a day, five days week to maintain our production schedule,” says Wickes. “And the robotic palletizer has decreased our labor costs because we no longer need to hire temporary employees during the busy season to palletize 50-pound bags. It also eliminated potential ergonomic issues related to operators’ manually handling so many bags.”

The bagger’s weighing accuracy has improved the company’s profit margin by decreasing product loss. “We’re very pleased,” says Jones. “The bag-weight accuracy range is really tight, and our customers are happy because they get exactly the amount of product they order.”

Both Wickes and Jones have been satisfied with the supplier’s post-installation operator training and follow-up service. “The supplier’s engineers were very good about training our operators on the new equipment and really got us up to speed,” says Wickes. “And even though it’s been a huge learning curve because the technology is still relatively new to us, the longer we operate the system, the better we get at it. The supplier has also been easy to work with and very responsive. If something ever goes wrong, their tech support is available until ten at night, so we can call them up and get answers over the phone, and that’s been very helpful.”

Article modified from Powder & Bulk Engineering Magazine, March 2009