How is the MgO board made?

The production process of MgO board (magnesium oxide board), also known as magnesium cement board, is a multi-step process that mixes magnesium oxide-based cementitious materials with reinforcing fibers and fillers, then undergoes molding, curing, and finishing. Below is the detailed industrial production process:
1. Raw Material Preparation
The core raw materials determine the performance of MgO board, and the ratio must be strictly controlled to avoid later deformation or cracking:
Main cementitious materials: Lightly burned magnesium oxide (MgO, content ≥85%), magnesium chloride (MgCl₂) or magnesium sulfate (MgSO₄) solution (adjusts the setting time and strength of the cementitious system).
Reinforcing materials: Alkali-resistant glass fiber mesh, plant fiber (wood fiber, straw fiber) or polymer fiber (polypropylene fiber) — to improve the board’s tensile strength and crack resistance.
Fillers: Perlite, fly ash, talcum powder, etc. — to reduce density, lower costs, and optimize thermal insulation performance.
Additives: Water-retaining agents, waterproof agents, anti-cracking agents, etc. — to solve the problems of MgO board’s easy water absorption and deformation.
2. Batching and Mixing
First, prepare the magnesium chloride/sulfate solution with a specific concentration (usually adjusted according to ambient temperature and humidity, with a Baume degree of 22–28).
Add lightly burned magnesium oxide powder, fillers, and additives into the solution in proportion, and stir at high speed to form a uniform magnesium cement slurry.
Add reinforcing fibers into the slurry, and continue stirring to ensure the fibers are evenly dispersed without agglomeration. The stirring speed and time are critical to avoid fiber breakage and uneven slurry mixing.
3. Molding and Forming
There are two mainstream molding processes for industrial production, adapted to different production scales:
(1) Flow-on Forming (Continuous Production, Large Scale)
The mixed slurry is uniformly spread on a moving stainless steel belt or PVC belt through a distributor.
Lay 1–2 layers of alkali-resistant glass fiber mesh on the surface of the slurry (or sandwich the mesh inside the slurry) to enhance the overall strength of the board.
Use a leveling roller to control the thickness of the board (common thickness: 3–25mm), and scrape the surface to make it flat.
(2) Mold Casting (Batch Production, Small Scale)
Pour the mixed slurry into a fixed-size mold (coated with a release agent to prevent adhesion).
Lay reinforcing fiber mesh in the mold, and vibrate moderately to eliminate air bubbles in the slurry and improve compactness.
Scrape the surface of the mold to ensure the thickness and flatness of the board are consistent.
4. Curing (Key Step to Prevent Deformation)
MgO board cannot be cured at high temperature; it requires gradient curing to ensure the hydration reaction of magnesium cement is complete:
Initial curing: Transfer the formed board (or belt with board) to a constant temperature and humidity curing room (temperature 20–25℃, relative humidity 50–60%), and cure for 24–48 hours. At this stage, the slurry gradually sets and hardens into a semi-finished board.
Secondary curing: Demold the semi-finished board and stack it in a well-ventilated area for natural curing for 7–14 days. Some manufacturers will use steam curing at low temperature (≤60℃) to shorten the curing cycle, but high temperature must be avoided to prevent the board from cracking or deforming.
Waterproof treatment: After curing, some high-end MgO boards will be soaked in waterproof agent or coated with a waterproof layer on the surface to improve moisture resistance.
5. Cutting and Finishing
Cutting: Use a CNC cutting machine or diamond saw blade to cut the cured board into standard sizes (common specifications: 1220×2440mm, 1200×2400mm) according to customer requirements. The cutting process needs to be equipped with a dust collection device to collect magnesium cement dust.
Sanding and trimming: Sand the surface and edges of the board to make it flat and smooth, and remove burrs and uneven parts.
Surface modification (optional): For decorative MgO boards, processes such as PVC film lamination, paint coating, or veneer pasting can be added to meet the needs of interior and exterior wall decoration.
6. Quality Inspection and Packaging
Conduct performance tests on the finished board, including density, bending strength, water absorption rate, fire resistance, etc., to ensure it meets national or industry standards.
Pack the qualified boards with plastic films or cartons, and mark specifications, production dates, etc., for storage and transportation.