Abstract: The process of molding thermal insulating blocks and electrical heating units with a mold having a horizontal filter screen in which a slurry containing a mass of inorganic fibers, water, and a binder is mixed to randomly orient the fibers and thereafter poured into the mold to divide the liquid component of the slurry into a first portion and a second portion, the first portion of the liquid component of the slurry being drained through the screen and the second portion remaining with the fibers, thereafter vibrating the screen and mold to drain a portion of the second portion of the liquid component of the slurry through the screen to produce a filter mat, thereafter drying the filter mat to remove the remaining liquid component of the slurry from the mat, and thereafter heating the filter mat to bond the fibers to each other. An electrical heating element may be mounted on the mold before the slurry is introduced into the mold.

Abstract: The process of molding thermal insulating blocks and electrical heating units with a mold having a horizontal filter screen in which a slurry containing a mass of inorganic fibers, water, and a binder is mixed to randomly orient the fibers and thereafter poured into the mold and a first portion of the liquid component of the slurry drained through the screen, thereafter vibrating the screen and mold to drain a second portion of the liquid component of the slurry through the screen to produce a filter mat, thereafter drying the filter mat to remove the remaining liquid component of the slurry from the mat, and thereafter heating the filter mat to bond the fibers to each other. An electrical heating element may be mounted on the mold before the slurry is introduced into the mold. The products produced by the process have densities in excess of 30 pounds per cubic foot.