combustible materials , including plastic sheets , plates , and blocks , also leather and all varieties of wood , may be cut along predetermined lines by engaging same with a heated reciprocating wire at temperatures which vaporizes the material rather than melting same . the machine providesa reciprocating wire which is heated by electrical resistance . a system of air quenching of the wire above and below the cutting zone is employed in order to attain incandescent temperatures at the point of cutting .