Gypsum Board Production Line

Overview

A gypsum board production line turns powdered calcined gypsum, water and two paper webs into finished wallboard in one continuous run. Stucco and gauge water meet in a fast mixer, the slurry is sandwiched between a face and a back paper, and the ribbon of wet board travels along a setting belt while the gypsum rehydrates and stiffens. A flying knife cuts the ribbon into panels, a dryer drives off the water left over from mixing, and the dry boards are trimmed, printed and bundled. The line runs without stopping for hours at a time, so every station has to hold its setpoint while the board moves under it at up to 200 metres per minute.

The line is organized as a wet end and a dry end. The wet end covers the Stucco and Slurry System system, the Forming Station, the Setting Belt and the Wet Cut-off Knife. The dry end covers the Wet Transfer and Turnover, the Board Dryer and the Finishing Section section. A Line Control System system ties the two ends together so the whole line behaves as a single speed-locked machine.

Mixing the slurry

Board quality starts in the Stucco and Slurry System system. Calcined stucco sits in a Stucco Surge Bin and is metered out by a pair of Stucco Screw Feeder units that weigh the mass flow as they run. Tempered water comes from the Gauge Water Skid, where a Gauge Water Pump and a Magnetic Flow Meter hold the water-to-stucco ratio, the single number that most affects board weight and strength. A Foam Generator whips foaming agent into stable bubbles that lower the finished density without weakening the core, and several Additive Metering Pump units dose accelerator, retarder and starch in small amounts. All of it enters the Pin Mixer, whose Pinned Rotor Disc spins on a hardened Mixer Drive Shaft driven by the Mixer Drive Motor. The mix spends less than two seconds in the mixer because gypsum starts to set the moment it gets wet, so the slurry must reach the paper before it stiffens. The blended slurry leaves through the Slurry Canister, which splits it into a face stream and a core stream.

Forming the board

In the Forming Station the slurry is laid onto a moving paper web. Two Paper Unwind Stand units pay out the face and back papers under steady tension, each with a Reel Shaft, a Dancer Tension Roll and a Flying Splicer that joins a fresh reel without stopping the line. A Face Paper Creaser scores the face paper so it folds cleanly around the edges, and a Roll Coater skims slurry onto the back paper for bond. The slurry pours onto the face paper, the back paper drops on top, and the sandwich passes under the Forming Plate that sets the wet thickness. A pair of Edge Forming Guide units fold the face paper to form the long edges, square or tapered depending on the product, and the Master Forming Roll pulls the wrapped board out at line speed.

Setting and cutting

The board is still soft when it leaves the former, so it rides the Setting Belt, a conveyor a hundred metres or more long. The Conveyor Belt runs on dozens of Idler Roll supports and is driven by the Belt Drive Pulley through a Helical Gear Pair in a Gearbox Housing, with a Belt Tracking Unit unit keeping the wide belt centered. Over this distance the gypsum crystals interlock and the board gains enough green strength to be cut and handled. At the end of the belt the Wet Cut-off Knife cuts the ribbon into panels. Its Flying Carriage rides on a Linear Guide Rail pair, driven by a Carriage Servo Drive and a Ball Screw, and matches line speed so the Cut-off Blade cuts square ends while the board keeps moving. A Length Encoder on a measuring wheel triggers each cut at the ordered length.

Drying

Cut panels still hold the free water that was added for mixing, so they go through the Board Dryer. First the Wet Transfer and Turnover section opens gaps with Accelerating Belt runs and uses a Board Turnover to flip panels so their good faces stay clean. The dryer stacks several Dryer Deck conveyors so many boards dry at once in a short building. A Air Heater Burner heats the air through a Heat Exchanger kept safe by its Gas Safety Train, Circulation Fan units blow it across the boards, and Exhaust Fan units pull the moist air out. The dryer runs hot at the inlet and cooler toward the outlet so the board does not overheat once its surface is dry, since driving the temperature too high would calcine the gypsum back to powder and ruin the panel. A Pressure Sensor watches gas and air pressure throughout.

Finishing and use

At the dry end the Finishing Section section squares the panels with an End Trim Saw pair, marks them with the Back Printer, and pairs them good face out at the Board Bundler before a Bundle Taper and a Stacker make them ready for the forklift. The whole run is coordinated by the Line Control System cabinet, where a Line PLC keeps every Conveyor Drive locked to the master speed and a Operator Station lets the operator load a product recipe.

Standard wallboard suits walls and ceilings; variants change the additives and paper for moisture resistance, fire rating or impact strength, but the line stays the same. Because the process is continuous and the gypsum cures in minutes, a single line supplies tens of millions of square metres a year for the drywall that most interior partitions are built from.