Along with its output and ease of changeover the machine's positive plugging and capping system was among the main reasons the monobloc was selected.
"The pick-and-place heads that install the tips and caps really work well" Bishop states. "We preferred this type of application but there weren't many machines in the market that had this feature. Most other machine builders use live tracks to feed the components to the application heads.
"We've had bad experiences in the past with vibrating tracks because the components seem to want to shingle over each other and they can become jammed. National designed this system so that it feeds from a bowl direct to the pick-and-place station 'nests' where they're picked up and placed into the bottle. We remain convinced this is a more efficient method." The nests are stainless steel and are machined to handle the size and shape of the plug being used.
The vacuum pick-up arms are servo controlled. They pick up the part from the nest swivel over the bottles and insert the dropper tips. The plugging pressure is closely controlled at the Filamatic's menu-driven microprocessor control panel.
Capping is done in the same way. The cap nests are machine-notched to accommodate the cap diameter. Once the caps are placed on the bottles each is pre-torqued onto the finish threads. The bottles then index to a second station for final torquing. Individual servo-actuated chucks tighten the caps to a level preselected at the control console.
"Mechanical clutch-driven torquing isn't consistent" he says. "This system allows us to set the application torque at the computer control. It's so precise that you can actually see one chuck stop when it reaches the predetermined torque while the other one continues turning for a split second.
"We don't use cap liners. But this system would be very helpful for lined caps where component variation is especially common. Small variations in liner thickness are added to the variations of the other package components."
The Filamatic will automatically reject a cap that doesn't match the preprogrammed torque level. However Bishop says it's rare for a bottle to be rejected for faulty capping with this machine.