... before extrusion. parameters:dimension of the rapid heating furnace: 4", 5" , 6", 7' , 8"total length of furnace equitment:21000mm,21500mm,21500mm ... ,18kw,18kw,18kw,18kwpower of combustion-supporting fan:4kw,5.5kw,5.5kw,5.5kw,5.5kwheating time:from20 to 520 degree celsius needs ...