Cold glue labeling machine

Labeling machine

Application example: Wine bottles labeled with cold glue labeling

The job of a cold glue labeling machine is to apply pre-cut labels to many types of containers. The beverage industry is an important field of application. Here, high-performance machines with an output of 60,000 bottles per hour and beyond are preferably used. Other labeling stations, such as stations for hot glue or adhesive labeling, can often be attached to the machine table of a cold glue labeling machine and can thus be combined with cold glue labeling.

Labels

Direction of grain for paper labels

Previously, labels only as award list considered for the identification of goods, today they are the calling card of the product. It is not uncommon for label design to make a significant contribution to the economic success or failure of a company. Paper labels are mainly processed with cold glue labeling, aluminum neck foils can also be applied with this method. Paper labels consist of special label paper with a weight per unit area of approx. 65 to 85 g / m² plus printing, painting or metallization. Along with many other factors, the grain, i.e. the direction in which the paper runs during manufacture, is of great importance for labeling. If you look at a label applied to a bottle, the grain must always be perpendicular to the bottle axis in order to prevent the label edges from rolling. Since the fiber run is not visually recognizable, a simple test procedure is required. If a paper is moistened, it always rolls parallel to the grain direction. This property of paper must therefore be taken into account when printing.

adhesive

Glue bucket with an inserted glue pump standing separately next to a labeling station.

The task of the adhesive is to permanently glue a label to a container, for example a bottle, until the label is deliberately detached in a bottle washing machine. Use is made of casein , Stärkeleime or dispersion glues. The selection of the adhesive is always based on the application and has a significant influence on the labeling behavior and also the performance of the labeling machine. A distinction is made between adhesives for glass and PET bottles, adhesives for ice-water-resistant gluing, which means that if the bottle is cooled in ice water for the consumer, the label must not come off within a specified time. Metallized labels usually require a special adhesive because the metallized surface prevents moisture from penetrating the label. The processing temperature of the adhesives is around 28 ° C. Depending on the type or manufacturer, it can of course deviate a few degrees up or down. Adhesive or glue containers can be integrated into machines or stand next to them separately. In the latter case, the glue is pumped into the labeling station by means of a glue pump, usually with a pneumatic drive and integrated glue heating.

Basic machine

A cold glue labeling machine, in the foreground the bottle inlet and outlet area.

A cold glue labeling machine essentially consists of a machine table with a rotating bottle carrier, an infeed screw to divide the jam-packed containers, the transfer stars for inward and outward transport and at least one labeling station. To protect the operating personnel and at the same time for reasons of noise protection , the machines are usually enclosed with cladding elements.

Image description for cold glue labeling machine

1: Infeed screw
2: inlet stars
3: Exit star
4: Centering hood
5: Incoming photocell
6: Machine casing

Labeling station

Illustration of a cold glue labeling station

Labeling stations can be permanently integrated in a machine or coupled as an exchangeable unit. In the latter case, one speaks of a modular design. How a station works: The labels are inserted into a label magazine with the unprinted side facing the machine. The glue segments rotating in the station roundabout pick up glue while driving past the glue roller, continue turning in the direction of the label magazine and immerse there for a length of approx. 1.5 mm. When moving backwards, they remove a label from the magazine, as it sticks to the adhesive-coated surface of the glue segment. The glue segment with the label that has now been picked up continues to rotate in the direction of the gripper cylinder. This takes over the label and transports it towards the bottle carrier. Sponges attached to the gripper cylinder finally press the label onto the container.

Image description to show a cold glue labeling station

1: Label box with label magazine
2: Station housing with the internal cam tracks
3: Glue scraper to regulate the glue application thickness
4: glue roller
5: glue segments
6: gripper cylinder
7: Bottle carrier

Control systems

Control systems are often used in labeling machines to monitor the result of the labeling. As a rule, these systems are coupled with rejection devices that eject all containers with incorrect labeling. The technically simplest system is to check whether a label is present. Depending on the application, this task is carried out by one or more special light buttons. An automatic check of the specified label position is more complex and therefore more costly. The position of each label is recorded by a camera as it drives past, passed on to a computer with high computing power and compared with defined default values. The correctness of the label, i.e. H. correct language of the imprint. If the preset tolerances are exceeded or if errors are detected when printing, the container is rejected.

Dating

In most applications, laser or inkjet dating systems are used to affix best-before dates or other information. Labels with printed date fields that are marked by scratching are less common today.

Bottle orientation

Some bottles, preferably bottles with drinks from higher price segments, are provided with so-called embossings, which make these bottles appear higher quality compared to simple bottles without embossing. Often, labels should be placed on the bottles centered on these embossings. To do this, the bottles in the labeling machine must be aligned accordingly before the labeling process. Mechanical alignment systems were used here in the past. These were based on a notch at a defined point in the wall of the bottle base, which was scanned by a metal finger located in the bottle plate. If the plate on which the bottle is placed was turned, this finger clicked into the notch and the bottle was aligned. However, this system can only be used for low performance. In addition, a notch in the bottom of the bottle is essential for the alignment function. In the higher performance range, cameras are therefore used in combination with powerful computers. The cameras record an unwinding of the bottle as it enters the labeling gyro of the labeling machine. Based on the individual images, the system can recognize the position of the bottle by comparing the images with a previously calculated and taught-in algorithm. When the current position has been determined, the computer can calculate the rotation still to be performed for the labeling position and pass it on to the control of the labeling machine via the bus system. With this system, bottle seams can also be recognized and the bottles can be rotated into a labeling position so that labels, in particular transparent adhesive labels, are not stuck over the bottle seam, which looks unattractive. One speaks here of a bottle seam detection.