New Presses, Robots And Low-Pressure Process

At its annual Technology Days conference and exhibition in Lossburg, Germany, Arburg GmbH + Co. KG introduced its largest all-electric injection machine yet, available with optional hydraulic accumulator-assisted injection, as well as the company’s largest vertical hydraulic machine to date and a line of entry-level robots with enhanced programming functions. The April meeting also demonstrated Exjection, a new sliding-mold, low-pressure “intrusion” process that allows production of long parts not suitable for extrusion.

Arburg expanded its electric-driven Allrounder A series with a new 220-ton Allrounder 570 A model (570-mm tiebar spacing). It is available with the company’s largest size electric injection unit, capable of a 15.3-oz, 28.9-in.3 shot—or with Arburg’s largest accumulator-assisted hydraulic injection unit for higher speed (55 mm/sec) and shot sizes up to 29.1 g/55.1 in.3 The machine also has Arburg’s Selogica Direct touchscreen control.

Arburg expanded its Allrounder V line of vertical/vertical machines with a new 55-ton Allrounder 375 V model, the largest in this hydraulic line. It has a fixed lower mold platen and down-stroking C-clamp.

Meanwhile, Arburg rolled out entry-level, three-axis, top-mounted beam robots, called the Multilift V Select series. They are based on the Multilift V series with its cantilever design and ease of integration with Arburg’s press controls. But the new models have a predefined set of features so they can be offered at lower cost. Sizes are available for each machine in the Allrounder A and S series. They handle maximum loads of 13.2 to 33 lb.

They have pre-programmed sequences for removing and setting down molded parts, although user programming of other actions is possible. A new robot teach-in function on the Selogica Direct machine control eases programming. In this teach mode, the robot is moved manually in a step-by-step sequence, while the positions are recorded automatically by the controller. The Selogica Direct control generates the robotic sequence and integrates it into the machine cycle. Robot movements can then be fine-tuned through the controller.

EXJECTION IN ACTION
A new low-pressure process that can mold long, thin-walled profiles integrating functional or decorative geometries was demonstrated by co-developers IB Steiner engineering consultants and Hybrid Composite Products GmbH, both of Spielberg, Austria. Their Exjection process provides a means of incorporating discrete features into a long profile, which is difficult or impossible to achieve by extrusion, while also accommodating low clamp tonnage.

In Exjection, a long mold slides either vertically or horizontally past a stationary injection gate. The process fills the mold continuously from the side rather than from the end, keeping flow length short, as the gate is always just behind the melt front. This method, sometimes called intrusion molding, reduces clamp requirements and stresses in the part. Proprietary controls coordinate mold travel with injection speed to ensure part quality.

Exjection allows a small press to mold parts up to 1000 mm long with a cross-section up to 10 x 16 mm and wall thickness from 1.5 to 1.8 mm. IB Steiner sells a license for 40,000 Euro ($61,500) per machine, which includes the control software. Both Arburg and Engel offer machinery for the process (see Learn More). At Arburg’s event, the Exjection process ran on the new Allrounder 375 V vertical hydraulic press, which was modified with an electric injection unit for precise screw-position control, electric-driven mold carriage and core pull, plus cavity-pressure sensors at the gate and end of fill.