Page 34 - Plastics News July 2018

FeAtures

A New Way to Mold Better Parts Faster and Easier

A new injection molding process ‘breaks all the rules’ by using low, constant pressure to achieve faster cycles
and better-quality parts.
GENE ALTONEN

rocter & Gamble is widely known as a consumer- Addresses common molding problems
Pproducts company but is perhaps less well known for
its R&D on improving the technology of plastics processing. The iMFLUX process addresses several challenges raised
P&G is itself a major consumer of injection molded by the conventional processing philosophy of using the
components for packaging, feminine-care products, rheology curve to establish an optimal filling velocity. This
toothbrushes, razor components, and other products. conventional philosophy generally results in filling the
mold very fast, to take advantage of the shear-thinning
P&G purchases many components from custom molders, properties of polymers.
and also manufactures internally within the Oral B
toothbrush businesses and the Gillette blades and razors However, this approach has several disadvantages, as it
business. P&G continually innovates in this space to generally results in very high molding pressures. Because
provide speed, cost, and design advancements the process uses a controlled filling velocity, the resulting
melt pressure is highly variable across different regions
Several years of the molded part. Figure 1 illustrates how pressure
ago, P&G varies throughout a typical part injection molded in the
recognized the conventional manner.
need to reduce
the cost and lead These differential pressures inherent in a conventional
time to launch molding approach result in multiple problems, including
new pl as tic differential shrink (or warp), dimensional variations,
part designs. flash, and the inability to accommodate wall-thickness
The goal was to transitions and part geometry.
completely rethink how injection molded parts are made The iMFLUX process resolves these issues by using a
in order to deliver breakthroughs in speed, cost, and constant low filling pressure, which results in uniform
quality. A company-wide research effort was launched pressures in the molded part. Rather than using a constant
and involved its injection molding technology experts. injection speed,
After exhaustive research, testing and pilot-scale the velocity is
demonstration, the team developed a breakthrough new allowed to vary to
technology utilizing low constant injection pressure. This maintain constant
new process enables thinking differently about how parts plastic pressure.
and molds can be designed. With this new discovery, P&G Figure 2 shows
decided to launch iMFLUX Inc. as a stand-alone, wholly how velocity varies
owned subsidiary. throughout an
The new iMFLUX injection molding process involves a iMFLUX process.
specialized controller that enables filling a mold at a lower, Filling slower yields faster cycles
defined melt-pressure profile, allowing a variable filling
rate that adapts automatically to the part geometry. The The iMFLUX technology controls the molding process by
advantages include improved part quality, new part and plastic pressure, rather than the conventional approach
mold design possibilities, sustainability improvements, of filling a mold according to a volumetric flow rate (also
and reduced capital expenditures. referred to as velocity filling). Controlling the process by
plastic melt pressure enables the melt to flow through a
The biggest breakthrough, which was unexpected and melt-delivery system and mold cavity without the potential
highly counterintuitive, was discovering that filling slowly
resulted in faster cycle times.

Plastics News July 2018 34