Published on the Packaging World Web site
| March 6, 2012
Controls optimize machine speed relationships
Ken’s Foods recently installed a new bottling line in its Las Vegas plant for, among other things, Sweet Baby Ray’s barbecue sauce, the world’s leader in the category.
Ken’s Foods recently installed a new bottling line in its Las Vegas plant for, among other things, Sweet Baby Ray’s barbecue sauce, the world’s leader in the category. Process & Production Controls, an integrator based in Norwood, MA, designed the controls package for the new line, and I had a chance to talk with that firm’s Erik Ekwall about the new line as well as about packaging line controls in general. Here are some of his observations:
We integrators are kept busy partly because most of the automation guys seem to be leaving factories and going out into the field on their own. So the base of knowledge that used to be in the manufacturing plants isn’t really there in those plants anymore.
Where Ken’s Foods needed help before we got involved with their packaging lines is in maintaining speed relationships among pieces of equipment. They’re buying good equipment and they are generally sizing it correctly, but they needed help on doing controls on the line. It’s a basic tenet of packaging line design that the filler must run at design speeds as much as possible. To do so it’s got to have equipment ahead of it that won’t starve it and equipment after it that is 20-30% faster so that it can draw out whatever the filler produces. Like other manufacturers, Ken’s Foods needed help coming up with the controls that could enforce those speed relationships. With this new line on the horizon, they came to us and said, hey guys, how do we make this line run better?
We have a database running on this new line that really dictates the speed of every major piece of equipment on the line. So an operator goes to, in this case, a Wonderware interface that we’re running, though you can use Rockwell stuff, too. We have a database loaded for every package size that they run on the equipment. They will select the bottle and it will load all the critical values into the PLC. By those I mean the optimum filler speeds, the high/low/medium speeds for the labeler, and the high/low speeds for the packer--all the changes that historically the operators have had to make. The problem with the operators making these changes themselves is that they don’t always get it in the sweet spot. So for the first day or so of production you’ve got this labeler that’s not exactly pulling bottles away from the filler the way it should be. Then the filler doesn’t run as well as it should because of that. So what we’ve done is we’ve more or less taken the human element out of the equation. Folks in the plant don’t have to make those changes. When they make a bottle selection it’s all driven through the machines by the controls systems.
We developed all the software for the line controls and all the graphics software. We happen to be using Rockwell PLCs and Rockwell motor controls. We used a Wonderware InTouch system out here for Ken’s Foods because that’s their preferred SCADA software in all their plants for process control. We have implemented similar systems with Rockwell FactoryTalk as well.
The entire conveyor layout, the entire production line layout was designed again based around the optimum filler speeds. So Ken’s Foods basically says that this is what we want to run our filler at and then works backwards and forwards from the filler. The unscrambler is rated for minimum 30% more than the filler is. With the labeler it’s the same thing. It was designed around a minimum 30% more than the filler can run at. It’s all based on machine speed relationships.
When you start with a ground-up design as we did here, you have a better opportunity to get it right. You are still limited by the equipment that you can buy and what’s commercially available. But what we have done is work with that new packaging equipment and then design the production line so that we can have, for example, the accumulation in the right spot. Then we design the controls to try to leverage those speed relationships.
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