1. Laminating tension
Generally speaking, there are two main types of label curl after lamination: upward curl and downward curl. If the label is curled upwards, it indicates that the film tension is excessive; If the label is curled downward, it is an indication that the film tension is too low. During the production process, the tension of the film is constantly changing. In general, the tension of the film is relatively small when it is first uncoiled. The higher the coil is reached, the greater the tension of the film.
Therefore, during the lamination process, it is necessary to adjust the tension of the film, increase the tension of the film when uncoiling, and reduce the tension of the film when it is about to run out.
Here, I will teach you a way to check whether the laminating tension is appropriate: after laminating, use a utility knife to cut the laminating material into several pieces according to the size of the finished label, and then remove the label from the bottom paper to see if the label is flat.
If the label is flat, the membrane tension is appropriate. If the label is curled up or down, the membrane tension is not appropriate and the membrane tension needs to be adjusted on a case-by-case basis.
2. Equipment problems
The lamination device on some older printing equipment is relatively simple in design, and the laminating tension is not adjustable or has a limited range of adjustments. The equipment will bring certain troubles to the operator, due to the lack of equipment adjustment space, once the laminating tension is not suitable, it can not be effectively adjusted, which can easily lead to the problem of laminating curl.
At present, the laminating tension of many newly listed printing equipment is generally adjusted by servo motor, which can solve the problem well. Therefore, the choice of laminating equipment is also very important.