The most common tube problem on a winding line is deformation: the tube going oval, its ends being crushed, or the wall collapsing. In this article we look at which cause comes to the fore in which situation.
Where does deformation appear?
It appears at three separate points, and the cause is different in each:
- During winding
- In handling and transport
- While waiting in storage
To solve the problem, you first need to establish which of the three it is. If an empty tube is sound when it comes out of the box but oval after winding, the problem lies on the winding side.
Deformation during winding
Winding tension
Yarn is wound onto the tube under tension, and every layer applies inward pressure. As the number of layers rises, the total pressure accumulates. If the tension exceeds the wall strength of the tube, the tube goes oval.
Symptom: the tube is oval when winding finishes; the winding surface is uneven.
What can be done: check whether winding tension can be reduced; if it cannot, increase the wall thickness.
Spindle fit
If the inner diameter is loose on the spindle, the tube drifts off centre throughout winding. That drift creates a one-sided stress.
Symptom: the winding has shifted to one side; the centre of the package does not coincide with the centre of the tube.
Moisture
Paperboard that has taken up moisture loses strength. The same tension that causes no trouble in a dry tube leads to deformation in a damp one.
Symptom: some tubes of the same size cause problems and others do not; the problem ones usually come from a particular batch or a particular storage area.
In handling and transport
Empty tubes are light and therefore vulnerable to knocks. The most common damage is crushed ends. A tube with a crushed end goes onto the spindle with difficulty, and even when it does, the first winding layers do not sit correctly.
Measures that can be taken:
- Tubes should be packed tightly and upright in their boxes
- Boxes should not be laid on their sides
- Forklift forks should not come into direct contact with the boxes
In storage
Two factors come to the fore in storage: moisture and stack height.
Moisture directly lowers wall strength. Direct contact with the floor, positioning against walls, and areas prone to condensation all carry risk.
Stack height determines the load on the tubes below. A tube kept under high load for a long period may not fully recover its shape once the load is removed.
Checklist
If you are experiencing deformation, work through the following in order:
- Is the empty tube sound when it comes out of the box?
- Is the storage area dry and enclosed, and are the tubes raised off the floor?
- Is the inner diameter right for the spindle, or is the tube moving on it?
- Has winding tension changed, or has a new yarn type been introduced?
- Has full package weight increased?
- Has stack height increased?
The answers to these questions usually explain the problem on their own.
When a change of dimensions is needed
If the source of the problem is a change in winding conditions — heavier packages, higher tension, a different yarn type — the tube dimensions may need updating too.
At Kafkas Masura we produce our tubes in custom sizes, to order. Share the problem you are experiencing and your working conditions, and we can determine the right dimensions together.