INNOVATION | LIQUID SILICONE RUBBER
Right: A specially configured IntElect 130 machine was used by
Sumitomo (SHI) Demag at K2019 in an LSR injection moulding demonstration
the conference, Ursula Nollenberg- er, the group’s Product Line Director for LSR Components, presented a case study of the two-component solution Trelleborg devised for a customer needing to address a product problem. The existing product was a control valve with a spring-activated piston, moulded in glass-filled polyamide 66, sealed in an aluminium housing with two LSR O-rings. Trelleborg set out to analyse and resolve a leakage problem with the valve, and also to reduce friction and eliminate assembly issues with the O-rings. FEA analysis showed there was a misalignment
of the piston in the valve which was stressing one of the O-rings. Trelleborg proposed eliminating the two O-rings in a new design for the valve which would be two-component moulded in PBT and LSR. The company used Sigmasoft simulation before going ahead with production. This showed that to achieve good moulding results, it needed to reduce the connection bridges, balance the flow and add an overflow in the part. The K2019 exhibition provided a showcase for other companies to show LSR machinery. Elmet highlighted its enhanced TOP 5000 P pneumati- cally driven LSR dosing system which has a smaller footprint than its predecessor. It has also devel- oped a TOP dosing system with a fully electric dosing pump which is driven by a torque- and current-controlled servomotor. The focus is on minimising dosing fluctuations and maximising efficiency and simplicity of operation. Both versions are intended for the mass production of high quality parts with tight tolerances. They cover shot weights from less than 0.1 g up to several kilo- grammes and viscosities ranging from 9,000 mPas to 3,000,000 mPas even when the viscosities of the two components differ greatly. KraussMaffei included LSR has one of its many K2019 demonstrations. It showed a small all-elec- tric PX 25 injection moulding machine with a clamping force of 250 kN in a medical LSR micro- injection moulding display. A micro membrane with a shot weight of 0.3 g was produced in an 8-cavity mould in a 14 s cycle time. For this applica- tion, KraussMaffei developed a screw measuring only 12 mm in diameter for extremely low shot weights. The company said its APC Plus machine function showed its strengths in this process, ensuring high shot weight consistencies and, consequently, uniform component quality. Sumitomo (SHI) Demag highlighted its LSR
24 INJECTION WORLD | April 2020
IMAGE: SUMITOMO (SHI) DEMAG
know-how at K2019 by moulding a component for a matrix light on a specially configured IntElect 130 machine. The company said the latest IntElect series uses 20% less energy than competitor machines. The series has an improved drive system, which is geared towards dynamics, precision and repeatabil- ity, it said. The new motor design is shorter and features new types of spindles. The all-electric IntElect 130 configured for LSR
processing at K2019 was equipped with a special screw, a non-return valve, vacuum pump and toggle technology. The cell was developed in collaboration with a number of the company’s partners that are dedicated to the LSR marketplace, including Nexus. Nigel Flowers, Managing Director of Sumitomo
(SHI) Demag UK, explained how the moulding machine differed from a standard IntElect. “Special screws, measuring between 14mm and 45mm in diameter, with a sealing system at the shaft are adapted to the material and machine size. Currently, the LSR package is available on IntElect machines ranging from 50 to 180 tonnes. Other special features include a spring-loaded non-return valve to avoid uncontrolled backflow of material, a shut off system specifically designed for LSR, plus a pressure con- trolled vacuum sequence to extract air and to prevent flash occurring during the filling of the mould.”
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.hella.com �
www.silcos.com �
www.wacker.com �
www.momentive.com �
www.sigmasoft.de �
www.rico-group.net �
www.arburg.com �
www.trelleborg.com �
www.elmet.com �
www.kraussmaffei.com �
www.sumitomo-shi-demag.eu �
www.nexus-elastomer.com �
www.dow.com �
www.germanreprap.com
www.injectionworld.com
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