American Hotwire Machines: Foam Types and Coatings
The most common types of foam which are suitable for cutting on a hotwire foamcutter
are expanded polystyrene foam and extruded polystyrene foam.
However there are many other foams available, and some are well suited to being cut with a hotwire.
If you want to cut a particular foam, contact us to find out whether hotwire cutting is suitable.
Expanded Polystyrene Foam:
This type is used for coffee cups, coolers, insulation, packaging products, and more. It is made up of about 2% polystyrene and 98% air. It is manufactured by heating styrene pellets with steam so they expand rapidly within a mold and form a large block of low density foam. The expanded beads remain as air filled closed cells that resist the conduction of heat, and therefore are efficient insulators. The foam is light, usually 1 to 2 pounds per cubic foot, and inexpensive. No CFC's are used in creating the foam. It doesn't degrade under normal circumstances because EPS is inert and has a very stable molecule. Foam is increasingly being recycled, to the benefit of the environment.
Extruded Polystyrene Foam:
This foam is the same chemical product as expanded foam, but is manufactured using a different process which extrudes the foam, resulting in a denser, more homogenous product with much smaller air pockets. It is commonly found in sheets of 2 pounds per cubic foot density or higher, and is usually colored blue, green, gray or another color. Styrofoam is a registered trademark of Dow Chemical and is a blue extruded sheet readily available in local lumber yards and from building supply outlets. This type of foam is excellent for making signs and display products.
Coatings:
Both types of foam are easily coated with water-based paints like vinyl acrylics, the paint is absorbed slightly into the surface of the foam by capillary action, thereby giving it a harder surface. For high gloss in any color and thick coatings that have a 3-D look, there are epoxy based coatings from companies like Coastal Enterprises or Copps Industries. Cement based coatings are most commonly found in the architectural field, and polyurea coatings are used for their hard, smooth finish. There are also metal coatings from companies like Plate-All and LuminOre. The foam shapes you create can have any finish your customer desires and can be suitable for use indoors or outdoors.