Hot-wire foam cutter

A hot-wire foam cutter is a tool used to cut polystyrene foam and similar materials. The device consists of a thin, taut metal wire, often made of nichrome or stainless steel, or a thicker wire preformed into a desired shape, which is heated via electrical resistance to approximately 200°C. As the wire is passed through the material to be cut, the heat from the wire vaporises the material just in advance of contact.

The depth of the cut is limited only by the wire length. Width of cut is limited by throat, if any.

All thermofusible expanded foams. This means those materials that melt at a relatively low temperature:

A preformed wire is attached to a handle. The operator manually guides the wire through the foam to cut freeform shapes.

A short tensioned wire is attached to a handle. The operator manually guides the wire through the foam to cut freeform shapes.

Hot wire foam cutting tables can use a vertical or a horizontal wire, usually with a horizontal table used as a guide or for securing the foam work piece.

A table with a vertical wire is mainly used by hobbyists to cut small and complex shapes such as letters. Only prismatic members can be cut on this type of table.

Tables with horizontal wires are heavily used in construction and packaging. The cutting wire is attached to tracks on either side of the table enabling it to be moved up and down making cuts very exact. This table type can also perform angular cuts.

A horizontal-wire manual table that uses templates placed on each side of a foam block to guide a taut hot wire to form a prismatic or tapered shape. The hot wire, tensioned with a bow or by springs attached to a rigid frame, can be propelled through the foam by hand or with a cord and pulley mechanism connecting each end of the hot wire to a weight. This method is widely employed by hobbyists to produce foam cores for model airplane wings.

Template-guided cutter accuracy is highly dependent on operator skill at fixturing the foam and guiding the hot wire along the templates. Accuracy is also affected by the precision to which the templates are formed and proper assessment and handling of kerf.

A vertical or near horizontal frame contains a set of evenly spaced parallel tensioned cutting wires. Massive blocks of foam are pushed through the frame on rollers or by gravity, thus slicing them into sheets that are sold as "bead-boards" for general use in construction work etc. The blocks are guided so little skill is needed by the operator. The frame holding the wires is often a replaceable and or adjustable unit so the spacing can be changed.

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Wikipedia