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The case of the durable string

KC Boxbottom untangles a string problem

“Hi, KC–my nozzles aren’t dripping and it’s a problem”

My buddy Sam was on the line.

“We have a new product and filling it is driving me bats,” she confided. “It fills fine but then just hangs there in a string. When the bottles index, the string pulls away from the nozzle and falls over the neck and side of the bottle. What can I do?”

“I’m on my way”, I told her.

When I got to the plant I saw the problem. The product was a viscous syrup. The filler was piston. Changing the valve timing for piston suck-back didn’t help.

“I’m near the end of my string, KC. The only way we can produce is to slow the filler way down. The plant manager is screaming for product and that’s not an option.”

“Fiddlesticks on stringing,” I exclaimed. “The problem is the viscosity of the product. One solution might be to reduce the viscosity by filling at a slightly higher temperature.”

“I thought of that, KC; Quality said no.” Sam replied.

“So we need to work with what you have,” I mused. “There are two ways to break the string each cycle. One is to inject a puff of nitrogen into the nozzle. An easier way in this case would be to use positive shutoff nozzles with a valve in their tip. As the valve slams shut, it jars the string, breaking it.”

We went with the valved nozzles.

No more stringing. Case closed.

KC Boxbottom, packaging detective, is on the case to solve tough packaging puzzles. He is the alter-ego of John Henry, CPP. Known as the Changeover Wizard, Henry is the owner of, a consulting firm that helps companies find and fix the causes of inefficiencies in their packaging operations. He produces a free monthly newsletter called Lean Changeover, which contains articles and tips on changeover and related issues. Reach him at [email protected].

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