Rethinking: Injection molding with low constant pressure
How the P&G subsidiary Imflux turns the basic principles of injection molding on its head
With a new injection molding process, Procter & Gamble has realized a paradox: faster cycle times can be achieved despite slower filling. For years kept behind closed doors, the P&G subsidiary Imflux now reveals more details about its injection molding process of the same name and opens the door for injection molders outside the Procter & Gamble environment. How does Imflux work? What are the advantages of the new process? Who can use Imflux? What are the requirements? How is it distributed on the market? K-PROFI spoke with Gene Altonen, co-inventor and now CTO of Imflux, at Fakuma.
Text: Dipl.-Ing. (FH) Sabine Rahner, Editor K-PROFI (German original)
For decades, we have learned that the melt is injected into the mold cavity at high pressure and high speed in order to compensate for the shrinkage of the solidifying mass by changing to holding pressure before the component leaves the mold. With Imflux, P&G has turned these basic principles upside down: the mold is slowly filled with a constant low pressure. This means that instead of conventional volumetric filling with constant injection speed, Imflux controls the injection process via a low, constant melt pressure profile. In this way, a variable filling rate is achieved that automatically adapts to the part geometry. The melt cools and compresses continuously, eliminating the holding pressure phase. Overall, a shorter cycle time is achieved despite a lower filling rate. Nevertheless, Imflux Inc. does not primarily focus on time savings, but on the interrelations resulting from the completely new process.
According to Imflux Inc., these are as follows: “High shear and pressure fluctuations are the reasons for high stresses, shrinkage differences, process instabilities, long cycle times and oversized systems. Low constant pressure creates optimum conditions in the mold that allow the melt to flow more uniformly and shrink more evenly. Distortion due to compressive/tensile stress fluctuations is eliminated. Lower pressure corresponds to lower closing forces. Temperatures and cycle times can be reduced, new design freedom in the cavities is opened up, smaller injection molding machines can be used and energy costs can be reduced”. Imflux Inc. puts the reduction in the required clamping force at up to 40 %. According to the supplier, the use of Imflux also results in improved overall system efficiency and quality, increased material flexibility, easy to implement thin-wall technology, sustainability through the broad application of recycled materials, more freedom in the design and choice of materials for the injection molds, and more.
Debut at Fakuma 2018
The process goes back to a development within Procter & Gamble, Cincinnati/Ohio, in the early 2010s. Gene Altonen, who holds several dozen patents, is a central figure of the then and now development team. When Procter & Gamble spun off the new development business as an independent wholly owned subsidiary in 2013, Gene Altonen followed as CTO of Imflux Inc. based in Hamilton/Ohio. The initial goal of Imflux Inc. was to establish the new technology within the injection molding world of P&G before it was widely marketed. In a first step, Imflux Inc. focused on P&G plants and suppliers to the group and held back with publications. Public appearances were limited to a few lectures at technical conferences or, for example, an open house event organized by KraussMaffei in Florence/Kentucky in October . 2017.
At Fakuma 2018, Imflux Inc. presented its process to a wider audience for the first time as a partner exhibitor at Milacron’s booth. “It’s our first show in Europe, but it’s also our first ever show. We have chosen the Fakuma because we have built a very strong partnership with Milacron in recent years and are continuing to move forward. Here we have the opportunity to present our process and talk publicly about it, including what we can do within this partnership,” commented CTO Gene Altonen to K-PROFI.
Imflux can be retrofitted to all injection molding machines
The use of the Imflux process is not limited to injection molding machines from a specific manufacturer. “We retrofit existing injection molding machines and tools for Imflux. The heart of Imflux is the software and a pressure sensor for the nozzle, which we provide in the form of a customer-specific adapter between cylinder head and nozzle. We have our own human-machine interface and our own hardware that can be adapted to any machine, regardless of its brand and whether it is a hydraulic, electrical or hybrid”.
A further important aspect for the Imflux process is the recording of the complete filling. The company has developed three different approaches to this, as Gene Altonen explains: “We have three basic strategies. Option one: we use a cavity pressure sensor in the cavity. Even for multiple molds, we only need one sensor. This variant has certain advantages, but is not always feasible. Then we have option two: the Nighthawk is a technology we developed with a sensor mounted on the outside of the mold that measures strain and has other advantages. This provides the processor with information on the spread of the flow front and supports the setup of the process and immediately detects any damage to the tool and stops it in real time. And then we have currently developed a third approach that does not require any sensor at all in or on the mold. This is a real breakthrough, because we still get feedback from the mold about the progress of the melt front. We can respond in real time without the need for a sensor. This is an enormous simplification. We don’t have to design a sensor into the mold; we save on installation costs and maintenance for the entire service life – that’s one of our biggest breakthroughs in recent years.”
Real-time control is at the core
In Imflux injection molding, the cavity is filled with a constant low pressure, usually between 25 and 50 % lower than with conventional injection. The process is controlled in real time by the melt pressure in the nozzle and the information from the mold. The instantaneous response to pressure variations in the cavity is essential for the Imflux process. Therefore, the algorithms used to describe these relationships play a central role in the Imflux software. “Ultimately, we sell software and sensor technology”, summarizes Gene Altonen.
Due to real-time control, the process automatically adapts to changing conditions. At Fakuma, Imflux Inc. demonstrated various possibilities using a 2+2-cavity mold for the production of round test discs made of PP or PE-HD with a shot weight of 56 g on a Milacron 1,550 kN Elektron Evo 155 injection molding machine. For example, some of the four cavities were randomly blocked by deactivating the hot runner nozzles. Result: Imflux compensated for the changes and the weights of the parts from the remaining cavities remained constant.
Automatically compensates for viscosity fluctuations
Furthermore, Imflux Inc. demonstrated at the Fakuma the real-time adjustment to strong viscosity fluctuations, a new feature implemented in the current software release 8.0 (from mid-January 2019). An example of this was a material change from white PE-HD with MFI 8 to red PP with MFI 20. Imflux automatically adapts the process via the filling rate to the changing melt density of these different materials. Here the melt pressure automatically goes from 530 bar for HD-PE to 250 bar for PP, without the operator having to do anything. All components are fully injected even during the changeover”. The Imflux process control realized the completely self-sufficient material change within a few minutes. In everyday production, an application could be the change from 100% virgin material to the addition of recycled material, which can change the melt viscosity. Usually, a machine operator has to adjust the process in several complex steps.
Premiere for fully integrated software solution
The Fakuma was not only a premiere for the public presentation of the Imflux process, but also for the direct integration into a machine control system. “This is the first time we have been able to offer Imflux in a fully integrated system,” says Gene Altonen and continues: “We have very good relationships with all machine builders, but with Milacron we have reached a different level in terms of both partnership and integration. This is by far the most seamless integration we have ever achieved with an OEM. Milacron has created a very elegant solution.”
Andy Stirn, Head of Application Engineering at Milacron USA, explains: “Our customers can subscribe to Imflux as part of the IoT package M-Powered, so that the license fees are covered.” The fully integrated software solution is expected to be available in the second quarter of 2019.
Hundreds of systems in use worldwide
So far, Imflux has only been used by retrofitting injection molding machines. “We already have hundreds of Imflux systems on the market, on machines from various manufacturers, but so far in the form of a retrofit solution,” reports Gene Altonen. The majority of Imflux systems are used in the USA, but there are also many systems in Europe, both within Procter & Gamble and with other global customers. Imflux Inc. does not provide exact figures or the names of licensees. “We have some, especially large, multinational customers working in a variety of industries, such as automotive, electronics, transport containers, etc., and we are very excited about the opportunities they offer. These are many different components, materials, part sizes, clamping forces. And we are successful across the entire range of industries and materials, Imflux works with both small components and large ones. We have already worked with clamping forces from 300 to 40,000 kN.”
One license per machine
According to Gene Altonen, the Imflux injection molding process is protected by hundreds of patents worldwide, in the USA alone there are around 80. Imflux Inc. opens up the use of the process by granting licenses per injection molding machine. “In the case of Milacron, Imflux can be used as a module within M-Powered as an annual subscription. According to Gene Altonen, this solution will be more cost-effective for the user than conventional licensing.
Finally, when asked whether the process reaches its limits with certain materials, Gene Altonen answers: “There is probably a limitation, but so far we have not discovered one.”
New Software Release 8.0
In mid-January 2019, Imflux Inc. presented a new release with the software 8.0 Suite. This includes the Auto Viscosity Adjustment presented at the Fakuma, according to the supplier a first step towards an autonomous injection molding machine. Another new feature is Precision Shot, which eliminates the need for a sensor in the mold. For the first time, the processor knows the exact shot volume and can control part weight and dimensions with greater precision. Process Navigator provides the operator with a new streamlined interface that simplifies operation and provides more real-time insight into what is happening in the mold. The fourth innovation is Auto Process Tuning, an automated function for fine-tuning the process to the tool, machine, material and environment.
Agreement between Imflux and Milacron
During Fakuma 2018, Milacron and Imflux Inc. announced the signing of a distribution agreement to fully integrate Imflux solutions into the control of Milacron injection molding machines. Milacron offers the option to integrate the M-Powered Imflux module directly into a customer’s new machine or retrofit most Milacron injection molding machines with an M-Powered Imflux upgrade. Milacron is the first machine manufacturer to offer this comprehensive integration solution, giving Milacron exclusive rights to offer the processing technologies patented by Imflux Inc. as a complete package. According to Imflux CEO Mary Wagner, the cooperation with the technology provider, which is also based in Ohio/USA, will start and at the same time the expansion of the work with the rest of the plastics industry will continue.
Gene Altonen (right), CTO of Imflux, and Andy Stirn of Milacron USA at Fakuma: “This is the first time we can offer Imflux in a fully integrated system.”
At the Fakuma, the Imflux process control realized a completely self-sufficient material change from white PE-HD with MFI 8 to red PP with MFI 20 within a few minutes.
Instead of conventional volumetric filling with constant injection speed, Imflux controls the injection process via a low, constant melt pressure profile. The variable filling rate automatically adapts to the part geometry. The melt cools and compresses continuously, eliminating the holding pressure phase.
Source: Imflux / graphic: K-PROFI
Imflux injection (bottom) fills the cavity with a constant low pressure, usually between 25 and 50% lower than conventional injection (top).
Milacron integrates Imflux solutions into the control of its injection molding machines. Customers can subscribe to Imflux as part of the IoT M-Powered package, which covers license fees.
According to Imflux Inc., hundreds of systems are already in use on injection molding machines from various manufacturers, always in the form of a retrofit solution.