Munich, Germany-Polyurethane machinery expert Krauss-Maffei Kunststofftechnik GmbH has developed a metering system for liquids containing abrasive materials that it claims overcomes the disadvantages of single-piston metering systems.
Constant flow is hard to achieve with a single-piston system, so Krauss-Maffei's experts have developed a two piston Tandem Hybrid PUR metering machine which "provides a good way out of this dilemma," said a statement from the Munich-based company.
Mixes containing fillers, flame inhibitors and reinforcing fibres are abrasive, and this causes "enormous wear on pump components" in traditional metering systems, explained the firm.
But constant flow is often essential, for high productivity, for example in applications requiring protracted shot times, or to supply several mixing heads. In Krauss-Maffei's Tandem Hybrid PUR metering machine, the abrasive component is fed by two pistons, operating in tandem. While one piston is discharging, the other is filling.
As well as the tandem method, the approach utilises sophisticated controls to ensure constant flow, even during piston switchover, the company said.
Krauss-Maffei says its Tandem Hybrid machine is "the right solution" for handling many materials including glass-fibre (in reinforced reaction injection moulding) and abrasive flame inhibitors as well as fillers such as wollastonite, barite or chalk.
PIC: Tandem piston metering from Krauss-Maffei, clearly showing the dual pistons, centre."