Harlacher, Saati, Grunig, Sefar
Things to look for are low tension areas within the screen, making sure clamps move well during the stretching process and ensuring good contact between the mesh and frame for glueing.
- Improper jaw tension (pneumatic or mechanical) resulting in mesh slippage - uneven tensioning.
- Pneumatic clamp cylinders leaking air during the stretching process.
- Pneumatic clamp cylinders leaking air during the lifting and lowering process.
- Pneumatic clamps sporadically not pulling or pushing.
- Mechanical clamps not sliding properly on the stretching rails.
- Mechanical systems not pulling properly on a particular side.
- Mechanical systems not raising and lowering the frame properly.
There are 6 main problem corrections needed
- Improper jaw tension: Most systems have wear parts that can be compensated for by adjusting how tightly the clamp jaw holds the mesh. In some mechanical systems, exchanging a few simple parts will correct the problem. Uneven tensioning can lead to uneven emulsion deposits.
- Leaking pneumatic cylinders: Can often be fixed with seal kits. Leaking cylinders cause a drain on the compressed air supply and can also cause uneven tensioning.
- Pneumatic clamps issues: Clamps that sporadically don’t function properly may have issues with the compressed air supply to each clamp. Crimped airline, poor connections, or a bad supply system. All of which will cause some clamps to pull differently than others.
- Mechanical clamp issues: Most mechanical systems rely on the stretching clamps sliding along a rail during the tensioning process to ensure even tensioning. There are a number of issues that could cause the mechanical clamps to not travel smoothly. Worn bearings, worn clamp track and excessive glue in the travel path. All of which would cause uneven tensioning.
- Wear points: Most mechanical stretching systems allow the operator to pull on at least 2 sides of the frame. There are a number of wear points that can prevent proper/even pulling in any given direction. These wear points can cause system failure.
- Lifting jack wear points: Mechanical stretching systems use a number of lifting jacks to raise the screen into contact with the mesh once proper tension has been achieved. The lifting jacks have a few wear points that if left unattended will prevent good contact between the mesh and the frame. If the contact is jeopardized, the bonding strength of the glue will be substandard and may result in failure.