To make EPS foam blocks from these small, rough beads, they must be "puffed" into larger beads, about 50 times their original size. This is known as a pre-expansion process. Depending on the required density, the pellets are blown with the help of steam in a device called an expander or evaporator. You can also get services of foam coolers in Hawaii from online sources.
An extender can be a simple manual machine where workers place raw materials and then ignite the steam. Or it can be an automatic machine where the material is blown and flowed automatically. At this point, the balls – up to 50 times their original size – are known as pellets and are ready to be printed.
The continuous pre-expanders are operated without pressure and equipped with an open tank where raw materials are continuously fed from below via an adjustable screw conveyor. Steam is also fed continuously into the pre-expansion chamber via an opening directly above the tank.
Regardless of the pre-expander used, they pour all the expanding granules into what is called a fluid bed dryer, where they are dried and stabilized before being transported to the storage silo.
The next step is to form the elongated kernels. There are two form options. Printing machines are used to shape the foam of the appropriate shape and size as needed. Others use a block forming machine that makes 3 x 2 x 8 foam blocks or panels to 5 x 5 x 24 inches.