Injection Molding: Faster, Smarter, More Efficient Machines Tackle Sustainable

A profusion of new and upgraded injection machinery at K highlighted twin themes of Circular Economy and Smart Manufacturing. While presses keep getting faster, they also grow ever more energy efficient in kWh/lb of plastic processed. The vast majority of injection machines at the show were all-electric, hybrid, and/or servohydraulic. This year’s exhibits featured machines equipped to process large amounts of post-consumer recycle (PCR) or biobased materials.

Reducing waste and downtime also contributes to more efficient and therefore more sustainable manufacturing. In that vein, K 2019 saw a continued push toward greater self-regulation in processing, greater connectivity between machines, and improved communication between humans and machines as milestones along the road to Smart Factories and Industry 4.0.

The following report presents news not covered in our September show preview and elsewhere for a more complete picture of injection molding news at the show. See also Keeping Up and Starting Up sections of this issue for additional K-related news. A report on robots will come next month.

Going for the ‘Green’

Our September show preview highlighted several exhibits of machines from Arburg, Engel, KraussMaffei and Wilmington Machinery tailored to handle large amounts of regrind or PCR, in some cases through foaming and/or sandwich molding.

Other examples at the show included Boy Machines processing wood-plastic compound (Fibrolon from FKuR) on a Boy 125 E. Husky highlighted the ability of its newest HyPET HPP5e system to mold PET bottle preforms from 100% PCR with no sacrifice of cycle time or product quality (e.g., color). What’s more, the Husky machine can take molten PET reclaim directly via melt pipe from Erema, NGR, or other recycling systems, thereby eliminating pelletizing, crystallizing and drying steps and saving large amounts of energy. Husky says customers prefer this approach to feeding reground flake. This “RMTP” capability is expected to be commercial mid-to-late this year.Machine capabilities to process large amounts of recycle or bioplastics supported the “green” theme of K 2019.

Chen Hsong demonstrated three-layer sandwich molding with recycle in the core. It utilized a second injection unit and an adapter plate to divide the two streams. And Milacron showcased its M-Powered integration of iMFLUX low-pressure molding technology, which is said to adjust automatically for large variations in melt viscosity, a potential risk in processing PCR. Milacron’s multi-nozzle low-pressure injection molding machine (LPIM) technology for structural-foam and structural-web molding is already to handle up to 100% regrind, and testing is underway with iMFLUX on LPIM machines.

Another “green” thrust in molding exhibits involved processing of biobased materials. One impressive demonstration in this vein was Nissei’s production of champagne flutes from PLA bioresin. Nissei says PLA has poor flow characteristics, but was able to mold this deep-draw drinkware with what it claims is the thinnest wall ever molded in PLA—as thin as 0.65 mm over a flow length of 125 mm. To accomplish this, Nissei came up with a new way to inject supercritical CO2 into the melt to improve the fluidity of the material. Remarkably, the glassware is crystal clear, owing to the use of only 0.5% CO2 and the microscopic size of the gas bubbles.

The glasses were molded in two parts, a base and cup in a cell utilizing two presses with Cartesian robots that deliver parts to an assembly station with a Kawasaki DuAro two-armed collaborative SCARA robot. The machine were Nissei’s brand-new, all-electric NEX 280V-71E (details below). One press molded the 185 g cups in eight cavities in 37 sec, and the other molded 108 g bases (o.74 mm thick) in four cavities in 72 sec. (Nissei will be speaking about this application in the Green Molding session at the Molding 2020 Conference, March 17-19 in Lombard, Ill.)

A new option on J-ADS all-electric auxiliary machinery from JSW is said to be advantageous for molding thick-wall parts from PLA and other resins. The optional JS servo drive is said to enable extended hold times together with fast injection and high responsiveness.

Another unusual demonstration at K was the debut of a machine and material for molding a new kind of eco-friendly products. Zeroplast is a patented material from a Polish company of the same name (zeroplast.com) that is composed entirely of mineral and nonfood plant-derived waxes, fibers and fillers (including rice hulls and calcium carbonate). This “plastic-free” material is compostable and biodegradable in natural environments. It is also recyclable without any loss of properties, the company says. The material is said to be heat stable to greater than 200 C (392 F) in processing and to 70-75 C (158-167 F).

Zeroplast worked with Wittmann Battenfeld on an exclusive basis to develop a bowing molding machine process for this material. The result is a specially modified, all-electric EcoPower 240 press (240 metric tons) with a special injection unit, heating system, and processing software. According to Wittmann sources, this system was adapted to the Zeroplast material’s sharp transition from solid to liquid and the resulting narrow process window.

At the show, Wittmann molded a thick-walled cosmetic jar and cap with the heavy feel of glass, molded in two colors in 4 + 4 cavities, with a paper in-mold label (uncoated for biodegradability) and automatic assembly of jar and lid in a screwing station outside the press. (Wittmann Battenfeld will present this innovation in the Green Molding session at the Molding 2020 Conference.)