Chelsea Milling doesn't advertise its home baking mixes to consumers. Instead, it relies on "our little blue boxes, as we like to call them," says Jack Kennedy, the Chelsea, MI, company's director of manufacturing operations. "The boxes are very much a part of the franchise of the Jiffy mix business."
And what a franchise it is. The company began producing a 40-oz all-purpose baking mix in 1930. Today it makes 19 different mixes on 17 packaging lines at the Chelsea plant, in five rooms, designated A, B, C, D and E. Room E houses four lines dedicated to Jiffy® corn muffin mix, which Kennedy says, "represents roughly 70 percent of our business."
One of the lines in Room E, however, was somewhat problematic. Specifically, an older two-scale weigher/filler had difficulty with the shortening that makes the mix somewhat clumpy.
"The machine was designed for more of a dry, free-flowing product," explains Chuck Elkins, packaging maintenance department leader. "The shortening sometimes caused the mix to 'ball-up.' So we were making the machine run something it really wasn't supposed to run."
Despite that, Elkins says, "We made the machine run for a lot of years, and it worked well for us, but we had to update it." The Michigan miller did just that in March, replacing the older machine on Line 17 with a Millennium 400 dual-lane, bulk-and-dribble auger filler from All-Fill (Exton, PA).
Chelsea is no stranger to packaging machinery and material upgrades. In the past two years, the company has upgraded bundling and tray packing equipment and added ink-jet printers for its corrugated shippers (see Packaging World, August '98, p. 58, or packworld.com/go/chelsea).
For this specific application, Chelsea's addition of the All-Fill machine wasn't done just for updating's sake. "The older machine we had been using needed regular attention," Kennedy notes. "And our product giveaway rate was about five grams per box. That's a lot on a 240-gram package. And the speed wasn't quite where we wanted it to be."
In looking for a replacement for the older filler, Kennedy says Chelsea "considered several options, including rotary fillers, but all-Fill was the only one with a performance guarantee of their speeds and accuracies in the straight-line filling system that we needed."
Chelsea's system was displayed by All-Fill at the supplier's booth at Pack Expo in Chicago last November. The machine was installed later at Chelsea's plant.
As this issue goes to press, Chelsea was in the early stages of commercial production on the machine, running it at a little more than 120 cartons/min. That's about 20/min more than the previous machine. Chelsea expects the filler to reach faster speeds in the near future. Besides speed advantages, the machine has already shown that it will reduce product waste. "Our giveaway is about half of what it was," confirms Kennedy.
Bulk-and-dribble
The key to the filler's accuracy, Kennedy believes, is its bulk-and-dribble feed system. "The fill occurs in two steps," he says. "At the bulk station, most of the package's 240-gram declared weight is filled. Then the carton moves onto an All-Fill checkweigher that feeds the weight information to the system's computer that tells the dribble feeder how much to add at the second fill station.
The line begins upstream as a double-package-making (DPM) machine strips off a small section of waxed paper from a roll and forms it around a heated mandrel that seals the bottom. The machine also picks off a carton blank and erects it around the formed wax paper inner liner. The bottom carton flaps are closed and sealed shut with cold glue, creating the "double package."
Converting by Chelsea
The cartons for the 81/2-oz Jiffy products are converted by a division of Chelsea, C&S Carton (Marshall, MI). C&S also supplies the corrugated shipping cases that hold these cartons. For these smaller Jiffy cartons, C&S offset-prints in five colors the 17-pt white clay-coated one-side recycled board from Smurfit-Stone (Clayton, MO).
Once the cartons with their inner liners are set up on the DPM, they are conveyed with little or no space between them down two infeed chain conveyors to the dual-lane filler. A timing screw delivers cartons through bulk filling, weighing, dribble filling and weighing stations on both lanes. Using the screws eliminates the need to use mechanical devices that could have damaged the tightly spaced cartons.
At the bulk-fill position on each lane, a pneumatic lift raises two open-top cartons toward the filling nozzles. According to All-Fill, the lift works in conjunction with a bag-opening mechanism that's mounted to the end of the discharge nozzles. The bag opener spreads the liner open to ensure that the mix will drop into the liner properly.
Minding the mix
Kennedy explains that the corn muffin mix is prepared in 8ęŻ -lb batches that serve all the lines in Room E. The mix is then dropped by gravity into a steel feed hopper. The hopper feeds the mix to an overhead covered conveyor that continues about 200' to a cone feeder on top of the All-Fill machine on Line 17.
To break up clumps in the mix, All-Fill installed rotary agitators to the bulk-fill hoppers that perform an alternating 180° reciprocating motion. The machine's augers were modified to help carry the mix down at higher speeds.
Another design change for the Chelsea application is the machine's bag-opening device. The carton's narrow 11/2" width was challenging enough, but the varying heights of the waxed paper liner could have been especially vexing during the fill. That's because the liner height varies up to 1/2" from carton to carton. All-Fill incorporated a 1" container lift to compensate for any height difference.
Bulk-and-dribble fill
Twin-head, servo-driven auger fillers dispense the mix. Chelsea specifies the number of auger revolutions for the initial bulk fill. Once complete, the bag opener closes and the pneumatic carton lift retracts to its original position. The two partially filled cartons are conveyed by the screw onto two platforms where each carton's weight is recorded. That information is communicated to the dribble-fill auger that delivers the second and final fill.
As with the bulk fill, the dribble fill uses a pneumatic lift that raises two cartons to two fill nozzles. A bag-opening device identical to that of the bulk-fill station works in harmony with the lift. The information from the checkweigher automatically adjusts the dribble-fill auger to provide an accurate fill.
After the dribble-fill, the bag opener closes, the lift retracts and the two cartons are advanced by the screw onto two platforms where they're weighed again.
Acceptable weights are predetermined by Chelsea. Cartons whose weights are outside of this acceptable range are rejected.
Cartons in the acceptable weight range are conveyed from both lanes to in-line top sealers that fold down the top of the liner before hot melt gluing the top flaps closed. The top sealers run slightly faster than the upstream fillers to prevent any potential build-up of cartons as they discharge from the fillers.
Kennedy says that Chelsea "is slowly converting [from other adhesives] to hot melt adhesive for top sealing because it allows the lines to run at faster speeds [than other sealing methods], requires less compression and provides better seals." He says the hot melt applicators are supplied by Nordson (Duluth, GA).
Cartons are then indexed to an accumulation system that handles the output of the four corn muffin lines in Room E. Cartons are packed into corrugated cases on semi-automatic equipment, then conveyed to a warehouse for palletizing, stretch wrapping and storage. The plant employs both its own fleet of trucks as well as common carrier vehicles to ship the baking mixes to retail centers nationwide. Kennedy says that the 81/2-oz packs retail for about 40¢.
Justification
Kennedy says the All-Fill machine on Line 17 runs 24 hours/day, five days/week, on three daily shifts. In late summer the line (and the plant overall) will likely shift to six days/week production for autumn and winter sales. He anticipates that the line will run 50 weeks of the year and produce 1.75 million 24-count cases.
He also notes the filler can handle other Jiffy mixes, too. But for now the company is delighted with its performance in packaging corn muffin mix. "We're filling at more than 120 boxes a minute, with repeatable accuracy, while reducing our product giveaway and the amount of maintenance. When we determine our payback, we look at the increased speeds of the new machine, less downtime for maintance, related labor savings and the ability to produce more product on fewer shifts. All those things add to overall productivity savings for us, says Kennedy.
In the company's payback analysis, Kennedy explains that a 100% return on investment would mean that the savings from the new machine would have to pay for the machine in one year. He says the payback time period Chelsea is forecasting for this machine is 1.4 years. "If you were to ask why we picked the All-Fill, the answer's right there," he states.
