Stock jumping

1. Most common cause of stock jump is foil angles are too high.
— check and correct.
2. Stock jump may be due to wake effect if rectifier roll is too close to slice.
— check roll position, hole size, and speed.
3. Stock jump is often generated through pitch or dirt accumulated at slice nip.
4. This is aggravated by dented, scratched, or generally damaged slice lip.
— improper slice adjustment can impart lateral velocity components.
5. Excessive breast roll discharge contributes to stock jump.
6. Stock jumps result from improper forming board adjustment creating disturbances at point of jet impingement.
7. Stock jumping is generally aggravated by higher machine speeds.
8. A slack wire can cause the stock to jump.
— adjust and check wire-tensioning device.
9. Stock jumps are generally reduced through use of grooved rolls, wet suction boxes and/or stationary drainage foils located between or in combination with solid rolls.
10. Usually, there are fewer stock jump problems with higher consistency forming.
11. Larger diameter table rolls and wider spacing of wire support rolls aggravate stock jump problems.
— shift to smaller diameter rolls, i.e., stationary core, anti-deflection rolls.