High-pressure equipment is used predominantly in applications that require measured “shots” to produce molded foams, insulation, and automotive components such as seats, instrument panels, carpet backing and fascia.
High Pressure Mix Head
The principle involves the impingement blending of chemical components under high pressure in the mix head’s mixing chamber.After metering a precise “shot” of chemicals, the plunger closes and cleans out the mix head. This system is self-cleaning and does not require flushing.
There are numerous styles of mix heads, each with associated options, depending upon the number of chemical streams involved and amount of mixing required. A straight mix head is adequate in closed-mold applications where chemical ratios are proportionate. For open-mold applications, in which the material flow is slowed and mixed further, an L-shaped mix head may be required. For additional mixing, pins may be added that interrupt the chemical streams.
The exact type of equipment required to deliver the chemicals at high pressure to the mix head depends upon the ratio and viscosity of the chemicals at the temperature they will be processed. Variable frequency drive (VFD) rotary piston pumps provide adequate pressure for relatively low-viscosity components. For high-viscosity and filled materials, lance-type cylinders are used. Since the quality of the finished, molded foam product is dependent upon the accuracy of the ratios of chemical flow, pressure, and temperature, the components of high-pressure metering machines are designed to maintain uniform flow, pressure, and temperature.