Because so much shrinkage happens during the injection molding of semi-crystalline thermoplastics, these materials usually require longer hold times. In standard injection molding processes, applying hold pressure and dosing are usually performed as two sequential phases. A new In-Mold Hold Pressure (IMHP) technology from DuPont Performance Polymers combines these phases, so they can be done in parallel. This reduces overall cycle times by up to 30 percent.
In IMHP technology, mechanisms that provide both methods are integrated within the mold, one on each side. The first method, applying hold pressure, is conducted by a hydraulically operated piston on the movable side of the mold. The piston is immersed in a specially provisioned and appropriately dosed melt cushion.
DuPont's In-Mold Hold Pressure (IMHP) technology combines hold and doping phases to speed up injection molding
of semi-crystalline thermoplastics.
In the second method, dosing, the molten material is made available in the hot runner on the stationary side of the mold. This melt volume is fed by pressing it into the cavity using a mechanism that works like a needle valve. DuPont continues to test and refine both methods with the goal of minimizing the additional space required in the combined, two-method mold.
The amount of time that can be saved depends on the degree of material crystallinity and the shot volume. Time savings of as much as 30 percent can be achieved with relatively short overall cycle times or large shot volumes. For example, when molding DuPont Delrin acetal resin using traditional sequential injection molding methods, the hold pressure time comprises a large proportion of the overall cycle time, according to Ernst A. Poppe, European manager for application and processing technology at DuPont Performance Polymers.
"We have conducted numerous injection molding trials with different semi-crystalline thermoplastic grades at our Technical Center in Meyrin, Switzerland, and were able to demonstrate, on the basis of producing standard bars used for tensile testing, the potential efficiency improvements," Poppe says in a press release. "IMHP technology is particularly beneficial when molding DuPont Delrin acetal resin." Delrin acetal homopolymer resins are commonly used in automotive fuel systems, as well as in conveyor belts and chains for industrial assembly.
The trials also demonstrated that no significant changes occurred, in terms of dimensional stability and mechanical properties, between samples produced with standard injection-molded techniques and those produced with IMHP technology.
To answer your question, Beth, it appears that the technology has not yet been fully commercialized, since DuPont says it is still refining and testing the two methods.
I am a little confused on how this technology is used especially in regards to the moving side mold cylinder. Where does the dosed melt cushion come from on the moving side of the mold. I can sort of understand adding material through the hot runner, but this is still hard to grasp. In most injection molding applications, all of the fill, pack, and hold pressures are applied by the injection screw. The length of time for pack and hold are determined by the gate freeze off time. Some better description of what this technology does would help in applying it.
Like most innovations, the total cost of adoption is based on the predicted savings and the cost to upgrade. 30% time savings is really attractive in a high-volume process, but that will be balanced by the cost to modify or replace the existing tools. I'm going to guess that DuPont has done their homework and charted a path that includes the cost of tool upgrades. Otherwise this innovation will take a large time to permeate production floors as they replace older equipment or build new lines.
Seems like a really promising technology and one that could have significant ramifications for manufacturers given the widespread use of injection molding in production. Is this a technology experiment or is DuPont further along in terms of trials or early use case testing, or perhaps even gearing up to commercialize the technology?
By experimenting with the photovoltaic reaction in solar cells, researchers at MIT have made a breakthrough in energy efficiency that significantly pushes the boundaries of current commercial cells on the market.
In a world that's going green, industrial operations have a problem: Their processes involve materials that are potentially toxic, flammable, corrosive, or reactive. If improperly managed, this can precipitate dangerous health and environmental consequences.
With LEDs dropping in price virtually every year, automakers have begun employing them, not only on luxury vehicles, but on entry-level models, as well.
From Dell / Intel® New Paradigms in Design Work Scott Hamilton, vertical market strategist for Dell Precision workstations, 5/2/2013 3
Early in my career, I worked as a draftsman and remember the days of drawing on vellum with numbered pencils and Mylar with plastic lead. This was a fun experience in the sense that I ...
I've been using workstations for more than 10 years and love finding ways to get more performance from my system. With demanding professional applications that require more power each ...
A lasting memory from my first job as an engineer in an auto assembly plant is standing on hard concrete at six in the morning, vending-machine coffee clutched in hand, listening to ...
A quick look into the merger of two powerhouse 3D printing OEMs and the new leader in rapid prototyping solutions, Stratasys. The industrial revolution is now led by 3D printing and engineers are given the opportunity to fully maximize their design capabilities, reduce their time-to-market and functionally test prototypes cheaper, faster and easier. Bruce Bradshaw, Director of Marketing in North America, will explore the large product offering and variety of materials that will help CAD designers articulate their product design with actual, physical prototypes. This broadcast will dive deep into technical information including application specific stories from real world customers and their experiences with 3D printing. 3D Printing is
To save this item to your list of favorite Design News content so you can find it later in your Profile page, click the "Save It" button next to the item.
If you found this interesting or useful, please use the links to the services below to share it with other readers. You will need a free account with each service to share an item via that service.
Tweet This
3 
