An industry veteran in Colorado, Rick Fitzpatrick, has developed a new type of injection molding machine that he calls “a clear departure from the reciprocating injection screw or traditional plunger machines.”
The press is small — current models have a shot size of 2 ounces. It's also low-priced, ranging from $12,000 to around $25,000. The press does not use much energy. Fitzpatrick is aiming the machine at companies that want to make a specific part, inexpensively, in-house, rather than outsourcing the work or sending the job to China.
He calls it the “part/machine” concept.
Fitzpatrick's molding machine uses a plunger running through the inside of a fixed, auger-type screw. The screw is used only to move resin pellets forward — it does not move and does not perform a heating and melting function, like traditional reciprocating-screw technology.
“The plunger moves, the screw is fixed,” Fitzpatrick said in a telephone interview from Berthoud, Colo.
He said his company, Koalesce LLC, is building and selling both horizontal and vertical models of the injection press, with shot sizes up to 2 ounces.
Fitzpatrick said his low-pressure process features highly accurate control of melt temperature. The auger screw pushes the pellets into portions of the barrel that are heated, using barrel heaters or cartridge heaters, aided by a special configuration of the inside barrel diameter, he said.
The plunger injects the melt into the mold.
Fitzpatrick has worked in the plastics industry since the early 1980s, as a mold designer and product designer, using everything from 72-cavity unscrewing molds to large, single-cavity parts. He has worked at injection molding companies such as Capsonic Group and DTM Products Inc., a company in Niwot, Colo., which was sold to Flextronics International Ltd.
Fitzpatrick explained the traditional thinking of plastics: big presses with high-cavitation molds, lots of electricity consumed and a major support structure.
“It's a subjective process and it takes many years of experience to get good at it,” he said.
But his process is easy to use “and will allow anyone to mold parts at a cost lower than competitors,” he said.
“It takes little experience to operate it effectively, because we define the process and marry it to a control system in a way that is not possible with existing machines,” Fitzpatrick said. “It's an amazing machine and the technology is scalable.”
Koalesce, based in Berthoud, has posted several YouTube videos demonstrating the injection molding machine. The company currently uses a toggle-clamping system, but Fitzpatrick said he plans to begin using a mechanical interlocking method later this year.