ELMET: New Dosing Systems Boost Cost-Efficiency in Liquid Silicone Rubber Processing

At the K 2010 trade fair ELMET focused on its role as an internationally active full-system supplier for the entire field of liquid injection moulding (LIM) of two-component liquid silicone rubbers (LSR). In the related field of multi-component dosing, users can now select between two high-performance equipment versions adapted to different tasks.

A newcomer to the ELMET product range is the TOP 1000 pneumatic dosing pump, which combines high reliability in rough day-to-day service with an attractive price. The unit is purpose-designed for moulding high-quality parts in standard high-volume manufacturing applications, and can operate on both 20-litre and 200-litre drum kits. At the fixed 1:1 mixing ratio, it is capable of delivering up to 2.5 litres per minute, depending on the viscosity of the liquid silicone material. Colorants can be admixed in three pre-selectable stages.

The same compact 1,250 mm x 1,050 mm footprint also accommodates the TOP 3000 dosing system, which is of essentially identical design but comes additionally equipped with a patented closed control loop. It is thus capable of providing constant, and documented, dosing precision with synchronous emptying of both LSR drums at the 1:1 mixing ratio pre-settable via the software. This ensures that the residual content in the drum will not exceed 1% upon a changeover, so that each raw material will be utilized to the maximum extent. All relevant process data such as filling levels, kit-change time, pressures, volumes, and colorant admixture data are monitored and recorded by the electronic system. The integrated programmable logic controller (PLC), sensitive sensors, and fast-responding actuating devices form a closed-loop control system guaranteeing constant high product quality. Process data required for quality assurance and documentation purposes are continuously logged and documented, and can be read out via an USB port. For use in global markets, eight operating languages are implemented as standard, but others can be added upon request. The TOP 3000 metering system can be configured in tandem for uninterrupted production.

For admixing colorants, ELMET colour lines are available in diverse configurations. They consist of a dosing valve combined - according to user preference - with a 0.7-litre pressure vessel with pressure monitoring unit and controller, a 4-liter pressure vessel or a 20-liter colorant pump, equipped in each case with a paddle mixer and level sensor.

Beyond cost-saving dosing systems, the ELMET range of products and services extends from fully automatic high-precision injection moulds (the company´s core business), to electronically adjustable valve gate cold decks and peripheral items such as check valves, diving nozzles, filter units, etc. At the customer´s request, ELMET will combine these products with customer-owned injection moulding machines to form turnkey, fully tested manufacturing cells incorporating perfectly matched components. Moreover, the company supplies pre-production (pilot) and low-volume production runs to customer specifications where specimen mouldings must be made available at short notice.