Know-How
Better Screening - Tips and recommendations
How to screen even better. Our tips and recommendations.
Service life
A key issue for economical sieving and sizing. Correct tensioning and optimum positioning of the screen are important considerations for optimum performance. Experience shows that a screen should last (in mechanical terms) for 500 to 600 operating hours. If this is not the case, it is well worth investigating the reasons why not. Reasons for a reduced service life for steel meshes can include tensioning, installation, the machine itself or the screenings.
Tensioning screens
Minimum screen tensions given in the data sheets are approximate values. Screens tensioned in accordance with these values will achieve good service life on most machines. In order to maximise the potential of the machine, an individual assessment of the tensioning values may be necessary according to the separation data. Correctly and evenly tensioned screens can achieve exceptional service lives. The finer the mesh, the more sensitive the tensioning process.
| Mesh weight (kg/m2) | |
| below 0.4 | exact tensioning vital |
| 0.4 - 0.8 | control of tension vital |
| over 0.8 | control of tension recommended |
In Practice, the following guidelines have proved valuable:
- Bring the mesh up to the recommended tension in stages. Increase tension alternately in warp and weft directions, always beginning with the warp.
- When tensioning fine meshes, check the tension constantly during the process using a tension meter.
SCREEN BLOCKAGES
Blinding particles: Some particles are fractionally too large to pass through the screen, and become stuck. Increasing the mesh count by 5% can bring about a significant improvement.
Build up of particles: Partial or complete blinding of the apertures by fine particles, often in combination with moisture. As a corrective measure, install a mesh with a greater surface area as well as sieving aids such as beads or brushes. When installing sieving aids, ensure that the additional mechanical loading is minimised as far as possible
