At National Custom Hollow Metal Doors and Frames, our fire rated doors and frames are subjected to rigid manufacturing standards, earning the label of Warnock Hersey Fire Doors and Underwriters Laboratories (UL). We use the industry standard galvanneal (steel with a galvanized coating that has been annealed to better accept paint) or stainless steel which is first cut to the specific size needed for manufacturing.
Then, the components have hardware openings precision cut on a Turret punch press to take door hardware and accessories such as hinges, locks, light kits and louvers. A Break Press is then used to form the door edges, ensuring precise fit inside the door frame.
After the forming step, hinge, closer, and lock reinforcements are spot welded into place, along with stiffeners if a steel stiffened core. Now it’s time to add the core.
Polystyrene, due to its light weight, insulation properties, and compatibility with many types of door constructions has become the industry standard in fire rated doors due to its ability to withstand high temperatures and block the spread of flames. Honeycomb, lead lined and steel stiffened cores are available.
At last, the two door halves are joined together and edge welded to form a single door and the completed assembly is taken to the finishing room where the welds are ground smooth and the doors are inspected, painted and labeled.
Labels provide information about the materials used in the door, fire rating, and other details to inform installers, building owners, and inspectors of the door’s properties.
At the site the doors are mated to fire rated hollow metal frames which are precision engineered for an exact fit.
We are proud of the precision, the durability, and the beauty of our fire rated doors and frames manufactured here at NCHM in Little Rock, Arkansas. Our rigid adherence to industry standards for fire resistant doors has earned our doors the label of Warnock Hersey Fire Doors and Underwriters Laboratories.