INNOVATION | OPTICAL MOULDING


Above: In a development by Arburg, the quality of transparent components can be significantly improved by flushing the material feed zone with nitrogen, especially in medical technology and optics


perennial issue. In order to manufacture optical products efficiently and reproducibly to a consist- ently high quality, it is necessary to master the complete process chain from careful material preparation to safe component demoulding. This requires a correspondingly advanced level of expertise in injection moulding.” Müller highlights the usefulness of smart functions


Right:


Automotive matrix lights moulded with precision on Sumitomo (SHI) Demag’s new LSR package


in the Arburg Gestica control system. The aXw Control ReferencePilot assistance function, for example, ensures precise holding pressure and constant shot weights. In conjunction with pressure sensors in the mould, the software feature uses reference curve control to ensure an even pressure profile in the mould and thus consistently high quality of the moulded part. Another assistance function of interest for the optics sector is the aXw Control PressurePilot, which enables “bionic” transition from injection to holding pressure. Both functions require the aXw Control ScrewPilot for precise screw move- ments and a constant injection process. At Chinaplas 2021, Arburg presented an LSR version of an Allrounder from the Golden Electric series for the first time. The electric machine was designed specifically to meet the demands of the Asian market. Integrated into a turnkey system with two robots, the exhibit manufactured sophisticated lenses for the automotive industry, such as those used in the matrix headlights of passenger cars. Each moulded part was 100% traceable. Parts of this kind must be designed with high precision in order to collect the light from the individual LEDs and deflect the light beams in a targeted and glare- free manner for a defined light distribution. Arburg now offers a turnkey solution for its


Allrounder injection moulding machines for flushing the injection unit’s material feed zone with


26 INJECTION WORLD | July/August 2021 www.injectionworld.com


the inert gas nitrogen. This prevents degradation processes due to oxidation during melt prepara- tion, which could lead to black spots or yellow discolouration. Particularly in the case of transpar- ent components, defects of this kind would be significant knock-out criteria for product quality. The nitrogen feed system is designed as a compact unit with integrated flow measurement. This enables the desired gas quantity to be easily and precisely adjusted via a pressure regulator. To cover a wide range of applications, the Selogica and Gestica machine controllers offer four selecta- ble functions. Nitrogen flushing is recommended for oxidation-sensitive melts – when processing PC and the COC and COP glass substitute materials, for example. The global silicone market size is projected to


grow from $16.7bn in 2021 to $23.4bn by 2026, at a CAGR of 7.0% from 2021 to 2026, according to a silicone market report by Markets and Markets. Sumitomo (SHI) Demag says that this rapid growth reflects the fact that LSR is fast becoming the material of choice for specific applications in the digital electronics and automotive segments. Other end-use industries include building and construc- tion, industrial and mechanical processes, aero- space, personal care and consumer goods, healthcare and transportation. “The increasing popularity of LSR can be attrib- uted to the thermal properties and the high level of design freedom it offers,” says Nigel Flowers, Managing Director, Sumitomo (SHI) Demag UK. “The pandemic has significantly impacted the market due to fluctuating demand from Tier 1 manufactur- ers, although this is anticipated to swiftly accelerate.” He says LSR is especially well suited for injection moulding but producing optics nonetheless requires high precision in mechanical engineering, tooling


IMAGE: ARBURG


IMAGE: SUMITOMO (SHI) DEMAG


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