Fine feathers make fine birds: fine labels make fine containers!
Labeling technology: an introduction
Rudolf Badura*
We're all familiar with the following scenario: work may be over for the day but there's still that quick trip to the supermarket to fit in. Guests are coming for the evening and we want to welcome them with a glass of very special sparkling wine. Connoisseurs already know which brand they're going to pick off the shelf. But what about those who don't really know anything about sparkling wine? After the price, popularity and presentation of the brand at the point of sale are probably decisive factors – a presentation whose success depends heavily on the type of label used. And here the following motto is of tantamount importance: fine feathers make fine birds and fine labels make fine containers! Any advertising and promotional activities – and especially all the positive brand images that have been created – can dissolve into thin air within seconds of spotting a badly labeled container. Under no circumstances should the pitfalls of poorly dressed bottles be underestimated. In the final analysis, this can even lead to loss of customers – and thus less ready cash for the company. Looking at it the other way round, a perfectly designed and successfully applied label is a selling point. With this in mind, it thus seems even more important that companies in the beverage, food, and non-food industries do all they can to ensure that their labeling process is nothing less than perfect. The following article should be treated as a basic introduction to labeling technology. Besides describing the various existing labeling techniques, it will deal with ways in which labels, labelers, labeling adhesive, containers, and peripheral line equipment can be perfectly coordinated; it also studies the labeling process as a whole. A brief conclusion on the future of labeling technology rounds off the article.
In the beginning was information
Labels are largely used today to convey information and generate popularity for the brand; they are the optical highlight of any container. This wasn't what they were originally used for, however. Initially, a label was only applied to a container to show the consumer what was inside it. Although it may be easy to tell whether a glass bottle contains milk or soda pop just by looking at it, with canned foods, this is more difficult! No label, no information on what you're buying.
* Manager, Labeling Technology Competence Center, KHS AG, Dortmund,
Tel: +49 (231) 569-1769
From manual to fully automatic labeling
Up until the 1950s, labels were usually applied by hand to the glass containers and cans then in common use. The manual application of labels was eventually replaced by semi-automatic and then fully automatic labeling processes. To start with, labeling machines only processed paper labels, sticking them to the cans and glass containers then available with water-based cold glue.
New containers and new labels call for new labeling techniques
When at the end of the 1960s the first plastic containers and later the first plastic film labels hit the market, researchers began experimenting with new labeling techniques and new labeling adhesives. They quickly found out that the use of cold glue labeling technology for plastic bottles may be possible but is totally unsuitable for certain areas of the industry. Paper labels stuck onto plastic shampoo bottles with cold glue, for example, peeled off when they became damp. They also discovered that film labels applied to various containers with cold glue didn't dry and thus didn't have enough adhesiveness.
Pooling these experiences, the task was then to develop labeling glues and labeling techniques that ensured a perfect synthesis of the labels used and the containers due for labeling. More or less at the same time, hotmelt and the hotmelt labeling technique were developed for paper and plastic labels, as were the paper and plastic self-adhesive label and the self-adhesive labeling process. Existing labeling techniques also provided the basis for the later idea of roll-fed labeling, practicable with both paper and plastic labels. Since the early 1990s, these techniques have included the newest labeling innovation: sleeve labeling. Only plastic film is used here, processed using stretch-sleeve and shrink-sleeve technology.
Varying maximum capacity
Companies today can now choose between cold glue, hotmelt, roll-fed, and sleeve labeling, all of which are described in the following. These labeling techniques not only differ in the processes they use but also in their capacity. Rotary cold glue machines, for example, can label up to 72,000 containers per hour, with rotary machines for self-adhesive labels working at a maximum capacity of up to 45,000 containers per hour. Up to 50,000 containers per hour can be dressed with hotmelt and roll-fed labels, with sleeve labels applied at a rate of up to 30,000 containers per hour.
Overview of the various labeling techniques
1) Cold glue labeling
If cold glue labeling is used, this usually means that paper labels are to be applied. Paper labels – or cut-and-stack labels – are stored in a label hopper. Each individual label is extracted from the hopper by means of a gluing segment to which a gluing roller shell has already applied glue. The gluing segment transfers the label to the gripper cylinder. This applies the glued side of it to the container. The label is then brushed on. One great advantage of the cold glue labeling technique is that a single labeling station can be used to apply several labels (such as body and neck labels). In addition, cold glue labeling is also reliable even if containers are slightly damp, as cold glue has no aversion to moisture. Paper labels applied using cold glue can also be easily removed in the bottle washer – which is particularly advantageous with refillable bottles. In the beverage industry, cold glue labeling is now largely used to dress refillable glass and refillable plastic bottles.
2) Self-adhesive labeling
Whereas in the cold glue labeling process there are three components to be carefully coordinated – label paper, glue, and container – the self-adhesive labeling technique has to deal with just two, namely the self-adhesive label and the container. This naturally reduces the number of interfaces. Self-adhesive labels are paper or film labels coated with permanent adhesive that are peeled off a label web during labeling. Transparent, self-adhesive plastic film labels are particularly spectacular and an excellent attention-getter. With their 'no-label' look, they appear to have been printed directly onto the container. Roll-fed labeling materials are normally used for self-adhesive labeling. The label material is fed to a dispensing edge, where a final extremely sharp bend causes the label to peel off the label web for subsequent transfer to the bottles. Servomotors precisely coordinate the speed of the moving container with the dispensing speed of the labeler. Optimum position accuracy is guaranteed. After labeling, the labels are brushed onto the containers. One clear advantage of self-adhesive labeling is the lack of format parts for various label sizes. Unlike cold glue application, no precisely contoured gluing palettes or gripper cylinders are needed. The drawback here is the high cost of labeling material – plus costs for disposal of the label web materials. In the beverage industry, self-adhesive labeling is used primarily for non-refillable glass and non-refillable plastic bottles since self-adhesive labels are usually extremely difficult to remove in the bottle washing processes used for refillable containers. The only exception are the more expensive wash-off labels that are available in both paper and plastic film versions and that are removed from the bottle in the bottle washer.
3) Roll-fed and hotmelt labeling
Even if the roll-fed labeling process is able to use paper labels, this technique usually entails the use of plastic film. Roll-fed labeling material is on endless rolls. This winds its way around several guide rollers to the labeling station. The labels are then cut and transferred to the vacuum drum. Here, the leading and trailing edges of the label are glued by the gluing roller shell and the glued label placed on the surface of the container. Once the leading edge of the label has been fixed to the bottle, the bottle is rotated and at the same time the label brushed on. After the trailing edge has been brushed on, the roll-fed labeling process is finished. It is also possible to apply individual paper or plastic labels with hotmelt. In principle, hotmelt labeling is comparable to the roll-fed technique. The main difference is that the labels are fed from a label hopper instead of from a roll. In brief, the labeling process is as follows. Strips or dabs of hotmelt are applied directly to the container. The container is then rotated past the label hopper where the adhesiveness of the glue removes labels from the magazine. The rotational movement wraps labels tightly around the bottles, after which a strip of glue neatly sticks the overlapping ends together.
Roll-fed labeling and classic hotmelt labeling are used in the beverage industry chiefly to dress both non-refillable plastic and non-refillable glass bottles. The reason here is that bottle washers also have difficulty removing hotmelt from containers.
4) Sleeve labeling
And now we come to the most recent labeling innovation on the market: sleeve labeling. The only labeling material used here is plastic film. There are two sleeve labeling techniques: stretch-sleeve and shrink-sleeve labeling. In the stretch-sleeve labeling process, a plastic sleeve fed into the labeling carousel is precision cut, stretched, and then pulled over the container until it is in the given position. The restoring force of the elastic plastic material causes it to fit snuggly around the container. While stretch-sleeve labeling is used in the beverage industry mainly for classic refillable plastic bottles, shrink sleeves are applied almost exclusively to non-refillable plastic bottles. These can also be contour bottles. The labeling procedure is practically identical to that of the stretch-sleeve method. The only difference here is that the film is not prestretched but pulled loose over the bottle. Unlike stretch sleeves, shrink sleeves are oversized in relation to the bottle diameter. After fixing the sleeve position, these shrink sleeves are selectively partially shrunk onto the container. Even for contour bottles, shrink sleeves thus provide the perfect fit.
Just a fashion fad?
Although certain labeling techniques are predestined to suit specific types of container, this by no means implies that they can't be used for anything else. In labeling, almost anything is possible. This is particularly important, as even container labels are subject to the fads of fashion. A few years ago in Eastern Europe, for example, paper was just about the only labeling material used. Now the focus is on plastic film – especially the no-label look, self-adhesive container label.
Tailored overall concept
Before a customer invests in new labeling technology, the line supplier should ideally first provide comprehensive advice. It is the supplier's job to make note of the customer's requirements, to assess whether these are feasible or not, to make suggestions as to current labeling trends and target group appeal and to then develop a tailor-made overall concept.
This tailored concept goes far beyond simply delivering the relevant labeling equipment. Right from the start, the supplier must ensure that the labeler, label, and label adhesive harmonize. At the same time, the line technology upstream and downstream of the labeler must form a unit with said labeler. When designing complete lines, for example, KHS sets great store by the fact that all demands made of the plant engineering by the container be met in each phase of the process. From the very beginning, therefore, the new setup guarantees that containers are fed to the labeler in such a way as to ensure perfect labeling results.
Close collaboration between the machine supplier, glassworks or plastic bottle manufacturer, label supplier, and the manufacturer of the labeling adhesive is always strongly recommended. KHS has the clear advantage that if a customer decides on a complete package from KHS, many aspects can be cleared up in house. The production of plastic bottles and label adhesive, plus the provision of labeling technology, for example, are all part of KHS' corporate activities.
As far as the labels themselves are concerned, the market today has a variety of very different labeling materials on offer. Paper or film labels in the right quality and surface finish should thus be selected to suit the application on hand. KHS has close contacts with label suppliers and can check labeling materials at its own laboratory, if required, where the general suitability of the label for the labeling process as well as the interaction of glue, label, and container are closely examined. A database containing practice-based information provides an additional cache of knowledge that is instantly retrievable at all times. KHS also enjoys a permanent cooperation with various external institutes and universities and is thus up to date on all fronts.
Modular or classic labeling technology?
Any customer investing in new labeling technology should also consider just how important the flexibility of the technique is to him or her. If a beverage company decides that it only requires cold glue labeling for glass bottles both now and in the future, then investing in a labeler with permanently installed cold glue labeling stations is the right thing to do. The advantage here is that the investment costs for a machine such as this are considerably lower – as opposed to a modular labeler. The big plus of modular labelers is that they are extremely flexible. Cold glue today, self-adhesive labels tomorrow and roll-fed or hotmelt the day after that: just use the relevant labeling station and they're all doable. With the Innoket SE, for instance, KHS has now launched a new generation of innovative labelers that meets even the highest demands for flexibility. The basic setup of the Innoket SE has deliberately been kept simple. It is comprised of an infeed table structure and a central labeling carousel. The labeling carousel can be configured with any combination of wet glue, hotmelt, roll-fed, or self-adhesive labeling stations. A camera-based alignment system can also be attached. In order to guarantee the utmost precision when labeling, KHS always uses a motor-driven bottle plate control in conjunction with a camera system if bottle alignment is required, for example when positioning a label to fit a specific embossing on the container. The camera unit examines the surface of each individual bottle without contact. Using the camera images, the system calculates which angle the bottles must be rotated so that they pass through each labeling station in the exact position. The bottle plate control then successfully puts the value calculated into practice.
When labeling stations are changed on the Innoket SE, the software and computer automatically resynchronizes all stations. Mounting and removing stations on the Innoket SE is extremely easy. Simple coupling and decoupling at one of the station locations provided on the labeling carousel is all that is required. In the Innoket SE concept, each labeling station is placed so that it can be positioned flush with the top of the table. An adjustable foot compensates for any unevenness in the floor. This always guarantees accurate alignment of the station with the machine.
Even if consolidating such a high level of flexibility in a single labeler sounds fantastic, deciding for or against modular labeling technology involves very careful consideration of the various pros and cons. Among other things, the following should be borne in mind: the more additional functions a labeler has, the larger and more expensive the machine will be. Before investing in new labeling technology, it is advisable that the customer consider whether two or more labelers that only meet specific labeling requirements would be better than one labeler offering the full range of options. In any case, there is no magic formula; each beverage company decides which solution is the best based on its individual requirements and demands.
What does the future hold?
There is also no magic formula for the future of labeling technology. It can be assumed that all currently existing labeling techniques will still be justifiable in the future. They will, of course, undergo continuous further development. In all probability, labelers will also be subject to development with regard to even more ease of operation. This increasing simplicity of labeler operation could also go hand in hand with easier reproducibility of settings. In this context, self-learning machines would be quite feasible. This would mean that any wrong mechanical settings could be electronically detected and, if applicable, corrected.
Alongside the various existing labeling techniques, digital printing could be of growing interest as a possible complement to or replacement for classic labeling procedures. Why not use digital technology to print additional information on a label aimed at a specific target group, for example? Or personally address regular customers with a message digitally printed on the label? Many things are possible. It is also conceivable that digital printing will increasingly be favored over the classic label, which would considerably reduce the number of interfaces needed in the labeler.
It is also likely that the extremely successful ReDiS (Remote Diagnostic Service) will continue to be developed. This in turn means that, on customer request, ReDiS is able to offer trouble-free support from KHS headquarters via modern diagnostic services. Should a malfunction occur, fast and uncomplicated assistance can be provided via ReDiS by accessing the control unit of the faulty line component. Another possible future aspect of ReDiS could be a recorded video to assist machine operators in answering any questions regarding mechanical equipment.
All in all, the topic of labeling technology is bound to increasingly awake the interest of the beverage, food, and non-food industries in the future. After all, with the marketing aspect of the label becoming ever more predominant, who would want to do without optimum labeling quality? It's not surprising, really, for fine labels make fine bottles – as fine feathers make fine birds …
