A complete examination

For some time now the most varied control devices are being used by the beverage industry. Over the past years inspection technology has developed with increased technical progress from simple sensor technology to complex camera inspection systems. A pure checking function at first regarding the presence of cases and containers progressed from the measurement of fill levels to the inspection of empty cases and containers. In the meantime a high technical standard has been achieved in the field of checking cases with empties and empty cases, sorting cases and bottles, inspecting empty bottles as well as filler and closer management.

On the other hand there is still room for improvement; a better-quality end-product can be produced by subjecting the individual containers to a final inspection. The ultimate inspection of the finished product - the so-called "final view" - has recently been growing more and more in importance. Regulations regarding guarantees commit the producer to prove that his product has left the production plant in perfect condition. In this connection checking the fill level, the function of the closure, the container itself as well as an inspection for foreign objects in the product have priority

However there are also additional factors which speak in favour of an intensive final inspection. Appearance is an important sales argument.What is the point of the most attractive labels if they have been incorrectly or only partially stuck on or have slipped or torn off during production? Up-market products in particular incur a loss of image if the quality of the packaging does not correspond with the quality image of the product.There are two positions along the production line where the above-mentioned faults can be detected: either after the closer or after the labeller.

The position after the closer is interesting because the closing process is complex and can produce a multitude of varying faults if the adjustments are not adequate.In addition the types of fault differ depending on the type of closure. When using crown corks faulty closures can generally be detected with a pressure measurement.Optical systems are better suited for checking plastic screw closures.The quality of the closure can be determined by measuring the position and fit of the closure and the tamper evidence ring.The faults occurring in the case of aluminium screw closures are even more varied.The complex rolling on process can result in a closure having a fault even though there is a temporary closing function.Such a screw closure can start to leak over a period of time resulting in the premature spoiling of a product.Furthermore the consumer could injure himself/herself when opening such a closure.

A correct closing process is only possible if the closure feed to the closer and the rolling on in the closer have been precisely adjusted and the new closures and container material are of the necessary quality.Specific deviations from the individual parts of this process chain result in specific faults. At present it is possible to detect the following types of closure and closer faults with a roll-on closure check:

bullnose - canted closure
weak thread - closure which was not rolled on with sufficient force
broken bridge - predetermined breaking points between the individual segments have been broken open prematurely
wingout - tamper evidence ring which has not been completely pressed on, individual segments are protruding
untucked band - a tamper evidence ring which is not pressed on at all

The statistical allocation of the closure faults detected to the individual closer stations with the closer locator make an efficient identification of the cause of the faults possible.Specific maintenance work can be carried out on the closer stations affected.This saves time and reduces costs. Not only is the total quality of the closing process increased immensely by means of this inspection but optimising maintenance procedures increases the efficiency of the complete filling line.

It is plausible that the position after the labeller is principally used to inspect the label dress of the bottle.The inspection of the labels is possible at two fundamentally different positions.This inspection can be integrated in the labeller after the individual labelling stations respectively.This involves the containers with labels to be checked being aligned and sent past the respective camera system in order to be inspected.The difficulty with this is that the inspection system must take the available space after the labelling station into account.However the marginal conditions vary from labeller to labeller and from station to station.As a rule easy access for changeover and maintenance purposes is not guaranteed.In addition to this an inspection unit is generally necessary in the labeller for each label position.This increases the total expenditure involved for implementing a label check.

New concepts in label checking now make it possible to carry out an extremely precise inspection along the conveyor.In this case the inspection in the labeller is deliberately not used in favour of an inspection after the labeller.Camera and mirror systems are placed in so-called optics modules so that the containers are viewed from all sides whilst passing along the conveyor.The individual views are put together by the software so that a continuous 360° inspection of the complete container circumference is possible.It is possible using suitable algorithms for the alignment of the container to become irrelevant for the image evaluation.In other words:  the software converts the picture as though each bottle was lined up in the same way on the conveyor.

Why this expenditure?Many of you will now be thinking that in general such marginal deviations from the required label position do not justify the use of such a device.However besides the purely "cosmetic" aspect of accurate positioning and alignment, a label without folds or creases, there are important features to check as regards consumer protection and safety. For example whether the correct label has been applied at all.If the consumer is provided with false information due to an incorrectly applied label regarding alcohol content (alcoholic / non-alcoholic), sugar content (sugar / artificial sweetener) and possibly ingredients unsuitable for those with an allergy the consequences can be serious. Damage to the label area which makes important information for the consumer unreadable should be detected with the greatest possible precision.In addition it is vital that the best before date is on the label and that the customer can read it.

The closure is increasingly used in addition to the label to represent a brand.The consumer can recognize at a glance on the basis of the logo which variety of a brand (normal / light / diet, with or without alcohol, different flavours) is in a case.However it frequently occurs that one or more closures from the same batch are printed differently.The technical possibilities of image processing today have also been so perfected that even in this case closures can pass under a camera system in no strict alignment and be accurately identified.

Modern systems combine the inspection of closure and labels in one device managing with one single illumination unit.The drinks producer is given the opportunity to accommodate a complete final check without major alterations to his line and with a minimum of space.

New systems for the detection of foreign objects are suitable for both positions. It can suddenly happen during production that the production machine breaks off a piece of glass in the course of the filling or closing process.There is also the added fact that the rinser does not always clean non-returnable bottles or jars adequately.Foreign objects which find their way into these containers during their manufacture are not rinsed out and constitute a danger to the end-user. The thought alone of drinking a piece of glass makes most people shudder.Special solutions have to be found for checking cloudy or completely non-transparent liquids or containers because optical systems cannot cope with this. Inspections based on X-ray technology in combination with image processing investigate the product thoroughly and can identify small foreign objects such as stones, pieces of glass or metal as well fruit pips.

Nowadays in particular it has to be the aim of every producer to supply the customer with a perfect product.Today´s technology makes a complete check of a product available to all.