Understanding the Problem
Gypsum boards are manufactured in a continuous production process starting with gypsum slurry, which is spread in a uniform stream onto a moving sheet of paper. This forms the front face of the plasterboard. The ‘back face’ paper is then applied to the slurry and at this point the front face paper is folded at the edges, producing an enclosed envelope of paper slurry.
Once formed, the long train of board travels the length of the production line to the shear, where it is cut into individual boards, which are then turned over for drying, during which, the excess water, which was required to form the initial slurry, is evaporated off.
During the drying process, the gypsum boards shrink but it is hard to predict exactly by how much they will shrink as this can depend on board dimensions, moisture, gypsum quality, paper properties and other factors, For this reason, the wet board is always cut over length to ensure an adequate safety margin to allow the boards to be trimmed to the desired length after they have been dried.
The LIMAB Gypsum Board Shrinkage Control Solution
By implementing a LIMAB length/shrinkage control system, it is possible to continuously and simultaneously measure the length of the wet boards immediately after the shear and the length of the boards at the exit of the dryer and then by comparing the two, calculate the exact shrinkage.
Once the exact shrinkage of the board is known, the over-length safety margin can be reduced without fear of cutting too short, which means the amount of board cut away after the dryer is reduced, saving both production costs and reducing waste.
Reducing the amount of board cut away after the dryer by just 2 mm, will save 0.08% of all production costs on a typical length board.
The LIMAB length/shrinkage control system can be supplied as a standalone solution consisting of two non-contact LaserSpeed Doppler length gauges, mounting brackets, laser photocells, cables, software integration, and site commissioning or it can be integrated into an existing GMS1100 gypsum board measuring system.
GMS1100 Software Integration
The length of the wet boards immediately after the shear (Avg. length knife) and the length of the boards at the exit of the dryer (Avg. length dryer) are displayed and length trend data is logged together with the other dimensional data for all boards produced.
The top screenshot shows the board profile, with average length at both the shear and the dryer. The bottom one shows the trends, including the lengths.
Benefits
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- Direct material savings
- Reduction in waste
- Use real data to improve the process
- Reduction in energy consumption
- Long-term dependability
- Easy installation
If you would like to find out how implementing a LIMAB gypsum board shrinkage control system could benefit your company, please get in touch.
