Tips for Cutting Foam

What is a hot wire cnc foam cutter used for?
Hot wire foam cutters will cut different types of foam, from insulation to fabrication, from logos, surfboards and signs to crown moldings and concrete molds
Hot wire foam cutters are designed to cut different types of foam
1. EPS – expanded polystyrene
2. XPS – extruded polystyrene
3. EPP – expanded polypropylene
Not to be used for cutting polyurethane – will result in toxic fumes

What are the main components that a foam cutter is made of?
1. The software is divided into two sections – design software to design the shapes to be cut, and the cutting software that controls the machine
2. The hot wire tensioning mechanism
3. Effective cutting sizes for the horizontal, vertical and the wire length
4. Number of axis – a 4 axis machine will be able to cut tapered shapes (like a cone or a jet wing)

Here are some features to look for in a hot wire foam cutting machine:
For production of crown molding:
1. Multiple wires – from 3 to 8 wires will increase the cutting capacity from 2 to 7 times
2. 8 foot effective wire length – don’t settle for a 4’ machine
3. If primary use of the machine is to cut logos and signs – a smaller machine will do the job
4. Cutting speed – mostly material dependent – as a rule of thumb: the higher the foam density – the slower the cutting speed

Foam cutting machines have many applications. They can be used to cut architectural shapes, for packaging, building, construction, hobbies, RC Planes, sculptures, monuments, theme parks, props, aeronautics, aerospace and much more.

Hot Wire CNC Foam Cutter prices:
CNC foam cutters will range from $1500 to $50,000. The price is a factor of the machine size, the number of wires, the way the wires are kept under tension.

Other foam cutting machines:
Another way to cut foam is with a CNC router – this is mainly for machining the foam and not for cutting.
CNC routers for foam are mostly used for 3D shapes seen in Las Vegas, theme parts and even signs

Foam coating: EPS and XPS will melt if painted with oil-based paint. Painting is composed of two steps:
1. Preparing the foam for coating – a primer should be used to prevent the coating material to penetrate the EPS beads
2. Coating – Coating is usually Epoxy (usually brushed) or Polyurethane (brushed or sprayed)
Once the foam is coated – it can be painted with any type of paint.

Cutting EPS Foam:

Expanded polystyrene is very easily cut with a hot-wire foam cutter, which is easily made by a heated and taut length of wire, usually nichrome due to nichrome\\\\\\\'s resistance to oxidation at high temperatures and its suitable electrical conductivity. The hot wire foam cutter works by heating the wire to the point where it can vaporize foam immediately adjacent to it. The foam gets vaporized before actually touching the heated wire, which yields exceptionally smooth cuts.
Polystyrene, shaped and cut with hot wire foam cutters, is used in architecture models, actual signage, amusement parks, movie sets, airplane construction, and much more.
Such cutters may cost just a few dollars (for a completely manual cutter) to tens of thousands of dollars for large CNC machines that can be used in high-volume industrial production.
Polystyrene can also be cut with a traditional cutter. In order to do this without ruining the sides of the blade one must first dip the blade in water and cut with the blade at an angle of about 30º. The procedure has to be repeated multiple times for best results.
Polystyrene can also be cut on 3 and 5-axis CNC routers, enabling large-scale prototyping and model-making. Special polystyrene cutters are available that look more like large cylindrical rasps

Resources

foamlinx.com
www.8linx.com
www.wecutfoam.com