Nozzle Shutoff Shuts Down Drool

When nozzle drool forces production pauses every couple hours and is measured in dozens of pounds a day, it has reached an unsustainable level. Klein Tools Inc. in Lincolnshire, Ill., a family-owned maker of premium hand tools, came to that realization when its vertical overmolding cells, which produce polycarbonate screwdriver handles with a soft-touch grip, began drooling to the tune of 7 to 10 lb after each shift. In addition to representing a waste of resin, the drool would collect and harden among the molding machine’s water lines, leading to leaks, damage and more downtime.

At Klein Tools’ production facility in Mansfield, Texas, each of the three screwdriver cells contains two vertical molding machines and a transfer system in which screwdriver handles are molded out of polycarbonate in the first machine and then overmolded with a softer cushion grip material in the second machine.

After some research, Jason Burcicki, manufacturing engineer at the Mansfield plant, settled on Melt Design Inc.’s Machine Nozzle Shut-Off device. Melt Design manufactured its shutoff device to be installed on the molding machine nozzle, giving processors added control of the flow of material into the mold and greatly reducing any drool.

Melt Design says this is especially applicable to insert molding, where the nozzle must back away from the hot-runner intake in each cycle. The company initially developed the concept behind the device to resolve issues a customer was having with a stack mold. Melt Design applied knowledge gained from that project—the patented Anti-Drool Sprue Bar Device—for this new device. The Anti-Drool Sprue Bar device stops material flow and prevents leakage from the sprue bar.

Klein Tools set a goal of reducing drool by 25%, but since the Melt Design device was installed in early April, the company has seen drool drop to less than 1 lb/shift, or better than 90%. Klein notes that the only material drool it still sees comes from the hot-runner side, not the machine nozzle. The device has also meant that Klein Tools’ molding technicians no longer must stop production every hour or two to clean out the drool, waiting instead until the end of each 8-hr shift. Ultimately, Klein Tools went from losing an average of 24 lb of drool per day at a cost of $2171.52 per month to losing only about 2.1 lb of drool per day at a cost of only $190.01 per month.

“Right away we noticed that there would be less scrap and less purge coming out of the nozzle,” Burcicki says. “Polycarbonate was the biggest hitter financially on our list of material scrap.” Because of the success with the first Machine Nozzle Shut-Off device, Klein added two more in May and June to outfit the other two screwdriver cells. “The financial impact of adding these nozzles was high,” Burcicki says, “and I am glad that we decided to try this method out.”