By David Reed, UT EditorSankt Augustin, Germany-Hennecke GmbH has introduced a gas-loading unit for use by makers of rigid integral skin foam products using reaction injection moulding (RIM). The device helps to create the extremely high number of gas nuclei required for the ultra-fine cell structure of such foams, and can be used with reinforced RIM systems, a statement from the German firm explains.The unit, designated Aeromat ST, allows the use of low-to-medium gas loadings below 25 percent and is fully automatic: All the operator has to do is enter the required density of the unloaded component and the desired gas-loading rate into the control unit - everything else is done automatically by the control system, Hennecke says.Gas-loading the polyol component is a widely used technique to yield good quality components when processing reaction injection moulded (RIM) and reinforced RIM systems, the German firm explains. During the reaction between isocyanate and polyol the gas produces a dwell pressure in the mould, thereby preventing the formation of sink marks, Hennecke said, adding that this considerably reduces trimming and finishing requirements.The ST unit operates on the same principles as Hennecke's long-established Aeromat GU unit, which is typically used at higher gas loadings, in the 50-70 percent range, the firm points out.The stand-alone modular unit can be operated in by-pass mode or as a system with an integrated pre-pump. In the latter case, the required admission pressure on the polyol metering pump is created by the Aeromat feed pump, rendering the installation of an additional feed pump unnecessary, Hennecke says.In addition, all assemblies are mounted on a separate base frame with an integrated, removable collecting basin, which allows for quick start-up and good accessibility of all modules for cleaning and maintenance purposes. The frequency-controlled circulating pump can be flexibly adapted to the operating conditions. The output of the circulating pump and the metering machine are adjusted to each other, Hennecke concludes."