How Metal Doors are Made

Egyptian DoorsThe earliest recorded mention of doors are represented in the paintings of the Egyptian tombs. And while the Egyptians believed doors to be the portal to the afterlife, more modern people have been building doors to stay alive! In this month’s blog post we discuss our metal door and frame supplier Mesker Door, and how they invented and construct metal doors.

A Brief History of Doors

First the Earth cooled, then the dinosaurs came, and in 1864, the Mesker Brothers began producing metal doors.

The Mesker Brothers’ breakthrough designs were fundamental to improving building standards and safety, becoming the predecessors to the modern hollow metal door and frame units we see today. Mesker’s doors and frames frequently exceed Steel Door Institute and Architectural Design specifications.

As the inventors of the Hollow Metal Door and the oldest manufacturer of hollow metal doors and frames in the United States, Mesker is proud to manufacture innovative products. Mesker uses the strongest American recycled steel in the construction of their doors and frames.

Quality to the Core

Metal door core designsThe core of the metal door gives it the unique characteristics that set our doors apart from others that may appear identical on the surface. The doors we stock come with cores of either the standard treadcore full polystyrene, flatcore full polystyrene or HDP flatcore polystyrene. A hollow metal door can only perform properly if it has the right type of core, made of the right materials, properly constructed, finished and installed within the door by the manufacturer.

Laser Cutting

Mesker incorporates a laser-cutting machine to precisely cut out flat shapes of the frame, or “blanks”, from flat steel sheets. Operators then position the metal between the upper and lower components of a die set, usually consisting of a lower stationary “die” and an upper movable punch. The punch and die are machined so that they fit together with close clearances and are designed to produce the desired configuration with a single hit.

Brake Forming

Brake forming is the method of forming steel on a machine called a press brake. Only straight-line bends can be made on the press brake. This is how the bends of the frame jambs are made. Brake forming is an economical method of forming straight-line bends.


There are three types of welding used by our manufacturers, fusion, spot and projection Welding. Fusion welding or metal-arc, uses a consumable flux coated rod, is commonly used to weld the miter and butt joints at the frame corners. This method of welding is fast and provides strong joints. Spot welding is a type of resistance welding commonly used in the industry to join two overlapping pieces of metal, face to face. It readily permits the joining of different thicknesses of metal without problems of warping or buckling. Projection welding is another form of resistance welding. The part to be attached by projection welding must first have a small projection of the proper size formed on it wherever the weld is to be made. Several welds can be made simultaneously at each such projection. This type of welding is used to fasten hinge and strike reinforcements on doors and frames, and floor anchors to the frames.

Hollow Metal Door Assembly

mechanically interlocking door designB&M’s metal doors are assembled with a pan and lid design and the steel sheets mechanically interlock together.
The core is used to provide a more rigid door, and also allows for additional features like energy efficient door insulation and sound proofing.

The three types of metal door cores are: honey comb, steel stiffened and polystyrene. After the doors are assembled workers inspect them for quality before entering the painting booth.

Metal doors are typically painted with a grey water based primer finish. This paint has a low VOC, meets the lead free paint requirements and is tested to meet the ANSI spec 25010 for prime paints. This primer finish allows customers to easily paint the door to any desired color after it is installed. Lastly before shipping is to label the door. The label is used to inform installation crews, building owners and code inspectors’ about the fire rating.

Have Questions?

We hope you have enjoyed this month’s blog, making hollow metal doors and frames.
If you have any situations during renovations or have new construction and you have any questions about metal doors and frames don’t hesitate, call us today! We will be more than happy to come out to your project and see what your Estimate requires.

Have questions about metal doors?  Contact us today!