KraussMaffei, world market leader in polyurethane processing machinery, has brought out new, optimized versions of its PUR mixing heads for the white goods sector. The new optimized PUR mixing head models have been developed in response to the increasing use of pentane as blowing agent. The very sticky reaction mix produced by pentane systems causes serious wear in processing machinery.
The company claims that the two transfer mixing heads, the MK 12/18-ULP-2KVVG and the MK16/25-ULP-2KVVG, have improved hydraulics for use in production of PUR rigid foam. These mixing heads can operate without cleaning between shots and supplied with a longer discharge tube (up to 120 mm) for easier access to hard-to-reach areas, deeper insertion and optimal positioning in the mould. These transfer head also use of a cap to keep the polyurethane components separate from the mixing head hydraulics. To mitigate the effects of sticky pentane systems, KraussMaffei engineers came up with a new solution for the metal surfaces in contact with the PUR. This is basically a friction-optimized bushing with a specially hardened surface and a patented spiral groove on the cleaning piston. When a pentane system is being processed, the foam moulds generally require cleaning with nitrogen. With these transfer mixing heads, the nitrogen can be discharged into the mould via the mixing head discharge tube.
The company's new version of MKE-3B linear mixing head has a special wear protection and operates on the 'T' mixing principle for outstanding mixing performance. One of the PUR components is pumped into the mixing chamber via two nozzles, the other component hits this component stream at right angles. Before pouring into the mould, any turbulence in the well-mixed compound is eliminated as it passes a series of calming pins. This quality engineering makes the MKE-3B the ideal choice for open pouring. Furthermore, it can be relied on to achieve six-figure shot numbers.
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