Patent ID: 8381381

Claim:
A manufacturing line to produce fire rated doors comprising: a first set of machines to cut two longitudinal interior channels into a back side of a door panel and two longitudinal interior channels into a back side of a second door-sized panel; a second set of machines to assemble a door slab by (a) inserting a spline in each longitudinal interior channel of the first door-sized panel, (b) attaching the back side of the second door-sized panel directly to (i) the splines inserted in the first door-sized panel such that the splines are also inserted into the longitudinal interior channels of the second door-sized panel and (ii) the back of the first door-sized panel using an adhesive, and (c) applying pressure to the door slab to bond the splines and the door-sized panels together; a third set of machines to cut a perimeter channel in each side of the door slab, and insert (a) an intumescent banding material in each perimeter channel, and (b) an exterior banding in each perimeter channel to conceal the intumescent banding material within the perimeter channel; one or more conveyors interconnecting the machines to move the door slabs; and wherein the fire rating for the door is achieved without a mineral core disposed between the first door-sized panel and the second door sized panel by (a) the intumescent banding material and (b) one or more of the following: (i) the adhesive is fire resistant, (ii) the first door-sized panel and the second door-sized panel contain an intumescent or fire resistant material, or (iii) the first door-sized panel and the second door-sized panel are coated with the intumescent or fire resistant material.