LOSSBURG, GERMANY (May 30, 1:30 p.m. ET) — Production efficiency was the focus of this year's Technology Days event, organized in March by injection molding machinery producer Arburg GmbH + Co. KG in Lossburg.
Arburg defines production efficiency as an overarching “meta theme” determined by eight key elements; injection molding machine technology, mold technology, ancillary equipment (peripherals), equipment configuration, process integration, process control, production planning and product design.
The company's four-day open house in March attracted over 5,200 visitors, 43 percent of which were from abroad, with 200 from Switzerland, around 160 each from France, Poland and Czech Republic and 140 from the US.
Some 2,700 visitors attended presentations by Arburg (on production planning), University of Leoben in Austria (on injection molds), BASF SE (on its easy-flow Ultramid B High Speed grade of nylon, and FPT Robotik GmbH + Co. KG (on inline printing).
The inline InkBot process presented by Amtzell, Germany-based automation specialist FPT Robotik was also shown running live, producing two-part, individually printed polystyrene name badges with 20s cycle time for two badges in a 2+2-cavity mold.
A 60-metric-ton Arburg Allrounder 370E 600-170 electric-drive injection molding machine, which was equipped with a Kuka 6-axis articulated “industry” robot integrated with Arburg's Selogica control system, were key elements of the production cell, as was the integrated inline printing system.
FPT Robotik developed InkBot in 2010 and previously showed a similar version running at Fakuma 2011.
Arburg said: “The integrated finishing process for the plastic parts means injection molders can increase added value and respond quickly to new demands in relation to changes of motif, thus giving them a competitive edge.”
In the presentation by FPT, the InkBot process was described as giving “naked” plastic parts — not only an individual “face,” but also a more pleasant tactile feel.
InkBot uses the Cyconjet UV curing combined primer, four-color ink and topcoat developed for industrial inkjet processes by Mankiewicz Gebr. & Co. GmbH & Co. KG of Hamburg, Germany, as used, for example, in Konica Minolta KM512MH print heads. The margin-free 600-dpi resolution printing can be applied as four available drop sizes in 4- to 4-pica litre sizes, with height difference up to 6 millimeters, as with the curved name badge.
Print motif selection can be made up to 500 milliseconds before printing and up to 250 megabytes of digital data can be transferred to the print heads within 500 milliseconds. Overall capacity is 1.8 GB for a maximum 1.5m2 image.
With printing speed of up to 0.8m/s, the inline system at Arburg ran at 50m/min inline with capacity of 250m parts/year. But InkBot inline systems can work up to 100m/min and can be dynamically adjusted. FPT Robotik says that InkBot production cells may also integrate labelling, assembly, packaging and quality assurance processes.
In the presentation of Prof Clemens Holzer of the University of Leoben on waste minimization, he said this is only really possible with sensors. But expensive pressure and temperature measurement sensors need to be further developed to reduce costs and encourage greater use for closer tolerance control.
New sensor types should also monitor other process variables. These could include sensors for viscosity and shear stress such as the PolySens sensor developed with project support under the Research Studio Austria scheme.
Holzer described a concept for installing ultrasonic acoustic sensors in existing mold tools to send melt-front data by wireless. He also recommended actuators close to the mold, such as the Priamus-Fill actuator, to reduce waste and obtain more consistent part quality. This is achieved through compensation of filling differences, maximum pressure limitation, targeted valve gate nozzle opening and simultaneous volumetric filling.
Such “intelligent mold” techniques should enable processors to cope better with the tendency of biopolymers to have more widely fluctuating characteristics than conventional polymers, Holzer suggested.
He said improved demolding of microstructure moldings can be obtained with mold coatings chosen depending on the polymer used, as well as by use of variotherm dynamic temperature control. Aside from other known advantages of variotherm molding, such as higher gloss surfaces, hiding weld lines and reinforcement fibres on surfaces, Holzer referred to other benefits, such as reduced shrinkage and warpage, faster cycle time for thick-wall parts, higher strength and easier molding of thin-walled components.
In particular, a peripheral wall of up to 250µm becomes a problem in microstructure surface replication, due to high temperature differences between the melt and mold wall, and this can be solved by variotherm processing, said Holzer.
Showing examples molded by Arburg, Holzer advocated core back molds for multi-component molding. Polymers are overmolded without opening the mold by simply using hydraulic sliders to open and close part of the mold cavity. Greater energy efficiency is obtained this way by eliminating mold opening for the secondary components.
He rounded off his presentation by advocating the use of nano fillers in plastics to increase thermal conductivity, enabling faster molding time for thick-wall parts through faster cooling.
Also in materials technology, Reinhard Jakobi and Rie Kaneko of BASF presented the company's high-speed nylon material. This material is able to reduce melt temperature by around 40° F for the same flow rate, and cut cycle time with faster cooling, leading to lower energy consumption. Lower injection pressure reduces wear and lengthens mold life, and offers the potential to use a less-expensive, lower clamping force molding machine.
Better flow brings greater production efficiency through simpler gate design and easier filling of thin walls, with associated lower scrap rates in complex parts. Examples shown at the Arburg event included an automotive clutch pedal in the B3WG6 grade and the Freund-Victoria Profiline axe handle in B3ZG6. Another five Ultramid B High Speed grades are available for sampling.
Arburg equipment innovations on show included the Arburg Energy-saving System (AES) for Golden edition machines. Variable speed pump drive and a water-cooled drive motor cuts energy consumption by up to 20% through continuous adjustment of motor speeds by a frequency converter. The variable speed pump drive enables higher speeds, resulting in higher pump output, and reducing dry run time by around 5%, as well as cutting noise, heat and dust emissions.
A new servo-electric driven twin-screw “Injester” was shown for more effective feeding of high-viscosity and pastelike compounds, such as moist polyester bulk molding compounds and solid silicone (HTC). Another benefit is simpler and faster cleaning. A classic design BMC ashtray was molded on an Allrounder Alldrive 470A 1000-400 with an Injester feeding unit.
No Arburg technology days event is complete without in-mold labeling, demonstrated this year with Viappiani and Verstraete labels in a mold from Van den Brink on a 720 H 3200-2100 hybrid drive machine.
In other demonstrations, wood plastic compound was molded on an Allrounder 570S 2200-800 hydraulic machine, and Trexel's MuCell microcellular physical foam process was shown in the molding of pizza cutters with a black foam handle and a compact yellow plastic cutting wheel on a 470S 1100-290 machine.
Aside from micromolding, precision molding was also represented by production of a Lamy fountain pen ink supply channel. This was produced in a four-cavity Lamy Werkzeugbau mold on an electric drive Allrounder 370E 600-700, fitted with an Integralpicker V vertical linear part removal robot. Cycle time was 22s for the 0.68g filigree structure black ABS ink channel parts. Lamy Werkzeugbau says it specializes in production of “rotational symmetric hollow parts with internal and external threads in combination with design oriented surfaces and invisible sprues”.
Optical part molding was covered by production of Fresnel lenses in a Momentive LSR material, as well as injection-compression molding of thick polycarbonate lenses. A medical application shown was a syringe housing molded in a 48-cavity Tanner hot runner mold in LyondellBasell's Purell HM671T grade of PP, achieving 13s cycle time for the 30-ml parts.