ITASCA, ILL. — Flip-top and dispensing closures are tricky precision-molding jobs, and it's important to have good part design up front, Arrow Development Group President Dieter Lay said at the Plastics Caps & Closures Conference.
“Part design has a direct impact on total cost,” he said.
Lay said the closure mold maker is the key.
“It's really important to have a conversation with the molder and the mold builder” during the design phase. Those plastics experts will know if new technologies make it possible to mold a closure today that may have been impossible five years ago, he said.
He got into design elements of a flip-top closure, telling conference attendees how things like shrinkage, sink and other molding problems can hurt.
The hinged flip-top cap has a male part on the top section, called a spud, which must match up perfectly with the orifice on the bottom section.
“When plastic shrinks you can end with an oval orifice, and now you're putting a round spud into an oval orifice,” Lay said.
The spud and orifice must make right contact for the full 360 degrees. If the spud is too long it can interfere with the front of the orifice, requiring an artificially high amount of opening force.
Arrow Development Group is based in Dousman, Wis.