Lightweighting, additive manufacturing in spotlight for Arburg

ROCKY HILL, CONN. — Arburg Inc.'s dedication of its new headquarters in Rocky Hill drew 160 attendees June 16-17, and after the ribbon cutting and speeches, they learned about lightweighting and additive manufacturing, and heard a 101-type explanation of hydraulics and pneumatics to power press movements.

Arburg also ran parts on five injection molding machines in the glass-walled showroom at the new 27,000-square-foot building, off I-91.

Heinz Gaub, managing director of technology and engineering at parent company Arburg GmbH + Co. KG, talked about lightweight parts.

Gaub said to make lighter parts, you have to optimize product design, materials and processing — which means a molder needs to work with good partner companies.

One way to do it is reducing wall thickness, or the part dimensions. He gave the example of the low-profile bottle caps, which are narrower and thinner than caps just a few years ago.

To reduce material usage, a molder can use foaming. Gaub said Arburg has developed a foaming agent added to the plastic granulate, which releases the gas upon injection. Another method is to use Aburg's long-fiber direct injection molding, which feeds fibers directly into the barrel, where the reinforcement is compounded into the melt.

Other lightweighting technologies include multi-material molding, particle-foaming and the use of fiber-reinforced organo-sheets to strengthen target areas of a part, Gaub said.

Grand opening attendees met Thomas Raymond, who runs the Freeformer laboratory in Rocky Hill.

Trevor Pruden, technical and engineering manager, said that, while injection molding is intended for mass production, the Freeformer is designed for smaller, batch manufacturing of production–ready parts, as well as prototyping. That concept of additive manufacturing matches up with several trends, for short product lifecycles and the need for more customization, he said.

Pruden said the Freeformer uses many of the same standard plastics materials a processor would use for injection molding. Traditionally, additive manufacturing machines required special, often expensive materials that had to be purchased from the equipment producer.

“The benefit is you have a wide range of materials to choose from. And standard additives,” he said. “You want to have the functionality comparable with injection molding.”

Gaub said Arburg began studying the additive manufacturing industry in 2004. The resulting Freeformer uses tiny droplets, built up layer by layer, to make a part.

The Freeformer looks like an office printer or a copy machine, with a smooth, rounded cabinet. Gaub said it marked the first time the machinery maker used an outside industrial designer for one of its machines. “Industrial design is a key part of new product development,” he said.

This year, Arburg has set up a dedicated assembly area to make Freeformers at its headquarters plant in Lossburg, Germany, Gaub said.

Arburg introduced the Freeformer at the 2013 K show in Germany, a model with three axes of motion. Company engineers are working on a five-axis Freeformer, Gaub and Pruden announced at the grand opening.

Pruden said Arburg will continue to add test new materials on the machine. “We will not stop developing this technology,” he said.

Hydraulics vs. electrics

Another speaker, Juergen Giesow, director of technology and engineering, explained hydraulics vs. electrics for machinery functions. With Arburg's Allrounder concept, he explained, a customer can mix and match the best power components on the same machine, he said.

Most machine functions are linear — such as mold open and close, carriage movement, ejector movement and core pull. Electric motors use rotary motion, so that must be converted to linear motion through belts and drives. Electric motors are naturally well-suited to screw drive, which also is a rotary motion.

Hydraulic power for injection molding presses has evolved from a single-circuit pump, which runs all the time and uses more power, to servo-hydraulics that allow the pump to stop if power is not needed, Giesow said.

Equipping the press with two pumps allows simultaneous movements — which can be enhanced with variable-frequency motors.

Giesow also addressed hydraulic accumulators, to give very fast and precise injection, hydraulic vs. electric core pull.

Which is the best? Giesow, who is based in Rocky Hill, said it depends on what type of parts the press will mold. “Step back for your company and look at your application,” he said.

Molding consultant John Bozzelli put a charge into the audience when he said that plastics, one of the largest industries, still has nobody working on the issue of melt temperature “on the fly.” “That's a basic premise to everything we do,” he said.

Companies conduct design-of-experiments mainly to check off a requirement from a customer, not to make better parts, Bozzelli said, adding that less than 5 percent of the time the DOE gets good useful information.

Presses running at the grand opening were:

An Alldrive with 165 tons of clamping force molding medical pipettes, with a complete Hekuma automation system, a 253-ton HiDrive doing in-mold labeling of lids, a 440-ton Allrounder 820 S molding parts with the direct-fiber compounding process, over an organo-sheet with a Kuka five-axis robot, a 170-ton Allrounder E injection press molding two-component silicone suction cups, and an Industry 4.0 demonstration with a 66-yon Edrive press molding components of toy cars. The Industry 4.0 system fully documents every step of production.