Low pressure injection molding technology offers faster cycles and better parts

The low-pressure injection molding technology developed by Procter & Gamble and now offered for license is intended to offer advantages in terms of mold productivity, part quality and freedom of design. iMFLUX Inc., Hamilton, Ohio, is a new subsidiary of P&G that was founded in 2013 to commercialize the technology. It grew out of a challenge from former P&G CEO AG Lafley, who asked why a company like Toyota could design and build a whole new car model so much faster than P&G could change the cap on Pantene shampoo. This resulted in the goal of building injection molds for P&G products in half the time and cost of traditional methods. The engineers at P & G identified the high pressure of injection molding as a major cost and time driver in mold construction and were pursuing ways to overcome this hurdle.

IMFLUX made its public debut at an open house in October organized by KraussMaffei Corp. in Florence, Ky. In a technical presentation, Gene Altonen, technical director of iMFLUX said that this low pressure technology offers economic benefits: 10-25% or more faster cycles, 25-50% or more reduction in melt pressure, up to 50% lower clamp tonnage and the ability to make thinner walls to shape without freezing and to increase the mold cavitation. Altonen showed two parts as 0.045 inches. and 0.025 inches. thick could be formed with the same pressure,
Save energy. The quality benefits of iMFLUX include lower potted stresses, more even filling of molds with multiple cavities, and the elimination of hesitation on the flow front for improved part aesthetics.

The iMFLUX process violates many of the rules of conventional injection molding. The key fills at a constant, lower pressure without the need for the usual shear thinning to facilitate flow. A slower filling without hesitation leads to faster cycles. This also allows for a cooler melt that can continue to flow through thinner channels. While in conventional injection molding the filling, packaging and cooling of the mold is divided into successive steps, iMFLUX combines all of them at the same time. “If you stop a quick shot, you’ll find it is fully wrapped and has a fully sculpted surface at every point during the filling,” Altonen said.

The proprietary software and controls use a pressure sensor in the machine nozzle as the primary control point to ensure even fill without hesitation in flow, based on sensing melt pressure every 1.2 milliseconds. Altonen showed a 3 “long runner that was only 0.030”. thick: “Any hesitation would freeze it.” A single cavity pressure sensor – regardless of how many cavities there are in the mold – is also used to sense the end of filling. This approach is intended to adapt immediately and automatically to any change in resin viscosity caused, for example, by changes in the quality or the percentage of the grist or by a change in color. Altonen said the cost of installing a cavity sensor could be saved by using an iMFLUX invention called Nighthawk, which is installed on the outside of the mold to sense strain and deflection as a proxy for measuring melt pressure inside the mold. Nighthawk provides all readings during filling, not just at the end like a cavity sensor.

Altonen cited the case of a mold with 16 cavities in which brief shots occurred at times. The addition of pressure sensors to each cavity showed a pressure range of 3439 psi at the end of the fill. With iMFLUX, this area shrunk to 1113 psi without changing the shape or the hot runner. Further examples of what iMFLUX has achieved are customers who have been able to switch a mold from a 700-ton press to a 400-ton press. Another reduces the cold runner volume by more than 50% while the cycle time is shortened. Resin consumption reduced by less than 25% with thinner walls than was possible with conventional technology.

iMFLUX can be installed on any existing mold and machine. iMFLUX also designs and builds molds to take advantage of its process technology.

Altonen will discuss iMFLUX technology at Plastics Technology’s Molding 2018 Conference 2018 from February 27th to March 27th. 1 in Long Beach, California. Information on the program and registration is available here.

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