The case of the sparky conveyor

It was a ho-hum kind of day and I was relaxing with my favorite magazine, Packaging Digest. The phone bleeped and it was Sammy. He was just starting production on a new line. “KC, my inkjet printer keeps crashing! If we don’t get the product to market on time it will cost millions.”

I grabbed my hat and was out the door. The printer used H-P inkjet cartridges to print a lot/date code on the blister card. Twenty minutes after I go there, the printer controller went black. Rebooting brought it back but each time it cost 5 minutes downtime. A backup printer was installed with the same results.

It took a while but I finally saw what was going on.

“Fiddlesticks on a bad printer,” I told Sammy. “The aluminum conveyor chain is not grounded electrically. A static charge builds up, reaches the tipping point and, ZAP!, it discharges to the printer’s aluminum encoder wheel. It’s just like touching a doorknob in winter. This jolt feeds back to the printer and knocks it silly.”

A quick fix was simple. I bolted a piece of copper wire to the conveyor frame and arranged it to drag on the pallets to discharge the static before it built up. Adding an “O” ring to the encoder wheel to insulate it electrically from the conveyor provided a permanent solution.

I don’t get the big bucks for fixing things. This fix was pretty simple. I get them for knowing what things to fix and this was a toughie.