Fast Food for Thought
A custom machine enables a Kentucky food processor to strip plastic film off chubs of meat before slicing into patties
October 1, 2019
by DAVID GERSOVITZ
Here’s something to ponder while you’re eating that breakfast sandwich at your favorite fast food joint. Imagine how that pork patty got to your bun. You might think that perfectly round patty travelled an unbroken path of automation from the meat packer to your restaurant.
Yet, as Toronto machine builder Nuspark discovered, there are gaps, like removing the plastic film manually from log-like chubs of processed meat before they’re sliced into patties.
The lack of an automated solution isn’t because of technical constraints; stripping chubs isn’t rocket science.
There are machines that do high speed stripping of hot dogs and sausages, but a Kentucky food processor couldn’t find one for stripping three-foot-long, four-inch-diameter chubs of processed meat for its patty supply operation.
At the customer’s behest, Nuspark designed and built a custom machine, which uses Festo’s stainless steel CRDSNU pneumatic cylinders to actuate most of the functions.
As Nuspark general manager Boris Motskin recalls, it wasn’t a job the Canadian machine builder was looking for when it first approached this customer––it’s well outside the former’s core business; in food and beverage, that’s end-of-line packaging applications.
“We went in there to look at some packaging automation, and the project we were discussing just kept getting put off and put off,” he says.
“Eventually, we asked them what bigger priorities they had, and they introduced us to this application.”
Nuspark scoured the automation marketplace to verify there wasn’t an existing solution that would meet the customer’s needs, and then proposed a custom one.
“We felt this would be a good R&D project for us and a good first project with this customer to try to get us into more standard applications.”
The customer also accepted that it would be an R&D project. It took about a year to develop, build and test the machine before it was installed last fall.
Stripping and slicing chubs is done in a cold room. These are unpleasant jobs for staff, especially the manual stripping, which necessitated rotating workers in and out throughout the day.
The first step for Nuspark engineers was to understand how an automated process might work.
“We knew how quickly specific devices work,” says Motskin. “But at the outset, we didn’t know how many devices we would need to incorporate.”
The customer’s specification called for stripping about 15 chubs a minute in continuous operation. Nuspark’s challenge was to achieve that without doing inordinate damage to the product.
“That means starting the peel, maintaining the integrity of the product so it still is a sellable piece of meat, then peeling it continuously throughout the entire length so there isn’t any remaining skin on the chub––we had to get all that right,” says Motskin.
A batch of chubs from the freezer is loaded manually on to a step feeder. The machine positions a pair of them for stripping along parallel pathways, then pushes them forward to the stripping mechanism.
Industrial sized pins are inserted into each end, which prevents the chub from rotating as a pair of jaws are lowered to make the initial incision at the top.
The front pins drop down, pulling the film with it, as the chub is pushed forward and out of the casing.
Although Nuspark had to make the incision as minimally invasive as possible, there was no avoiding some damage.
“You have to get underneath the film to begin removing it. That was something we had to work with the customer to understand––what amount of damage would be acceptable,” Motskin explains.
The rounded chub ends, in which the pins are inserted, aren’t suitable for restaurants, and are discarded. There is no discernible imprint of the stripping process on the patties, so the folks in Kentucky are comfortable with the finished product.
The throughput speed reflects a balance between the downward motion to cut the film and the forward motion to remove it––so there is just the right amount of slack, which assures there is no damage or film left on the chub. A pair of servos manage the speed throughout the peeling sequence.
Keeping everything clean is another challenge. The machine has to be washed down multiple times a day. The chubs begin to thaw as soon as they come out of the freezer, and the more the surface warms, even just a degree or two, the more fat and meat residue sticks to the machinery.
The Festo CRDSNU stainless steel cylinders and complementary tubing and fittings were designed for extremely easy wash down and extremely long, uninterrupted service life in sectors like food and beverage.
“Our main concern in selecting these cylinders was to have this in a cold room environment where they will be exposed to a rigorous cleaning on a continuous basis and make sure we don’t have them failing,” says Motskin.
“We have them in various sizes, actuating practically all functions – essentially everything from the initial infeed to the actual stripping, to the final push to remove the rear clip and release the chub to the discharge table.”
The newest CRDSNU variants offer features like self-adjusting end cushioning and long-life dry-running seals.
The cylinders on the Kentucky machine include the self-adjusting cushioning option, which means they never need the periodic adjustment required of manually adjusted cylinders.
If there is a larger market for it, the machine builder will likely have to adapt it to other sizes of chubs–– there is no standard chub size supplying the fast food market.
Some food processors might require a machine with the flexibility to handle multiple sizes or different meats, like hamburger or minced chicken.
But right now, that’s only food for thought.
Down in Kentucky, Nuspark’s pioneering machine is stripping almost 14 chubs a minute in continuous operation. Each chub yields 24 patties, so a minute’s output is sliced into over 330 patties. If you happen to be having breakfast in the Bluegrass State, you may be eating one.