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Never again: 24 hours of producing leaking bags


Project details

All products were leaking and this stayd unnoticed for 24 hours
Leak testing vacuum bags immediately after sealing
Vacuum packed coffee

Related cases

Ever since vacuum packaging was introduced, the coffee sector has struggled with one problem: microscopic leaks can only be detected after 16-24 hours.  Sometimes machines can produce leaking packaging for hours on end without anyone noticing.

For a long time the only way of knowing whether there was a leak in vacuum packed coffee was to squeeze the bags. Quality checkers would squeeze each pack to see if it was soft. This checking process has now been partially mechanised. Within a second or two of being sealed the seal is tested and ten minutes after production a mechanical system extracts the leaking packs. But this only detects the bags with really big leaks.

Current leak detection method
Small leaks can be detected by allowing the packed coffee to stand for a day. The process works as follows.

  • The packs of vacuum packed coffee are packed on trays and stored on a pallet in a warehouse.
  • After four hours the pallet is pulled out from the stack and a quality control person presses on the outside of all the bags.
  • If the quality control person finds more than two soft bags then the whole pallet has to be unpacked and all the separate trays checked manually.
  • Pallets that pass the test are then put back in the warehouse.
  • The same process is repeated 12 hours later.
  • Eight hours later the last check is carried out although this is sometimes not done.
  • Only after 24 hours in total can the coffee be sent to the retailers.

This system of testing is laborious and time consuming. Moreover it is not effective. Despite all the testing and checks leaks still occur in the packaging.

That is when panic sets in
Finding out exactly how many packs of coffee have leaked is difficult to determine. And as long as the percentage of leaking bags does not badly affect production statistics, not a lot will change. The vacuum packed coffee sector has learned to live with the weaknesses of checking for leaks after production. There is no budget to thoroughly tackle leak detection. That is until leaking packages roll off the production line for 24 hours non-stop. When this is discovered all the production run has to be cut open and repackaged. It is only then that management gets a real idea of the actual cost of this failure. It is at this point that the problem is so big that a need arises for better leak detection, to ensure it will not happen again in the future.

Even micro leaks can be detected within ten minutes
Oxipack has developed an in-line leak detection method that can measure the very smallest of leaks within ten minutes after vacuuming and sealing.  This is done by measuring the pressure in each pack for a few seconds and then comparing this reading with the pressure in other packs. Deviations indicate a leak. The pressure in the bag can vary if the speed of the production line changes because the aroma is released during the production and packaging process. To deal with this, the in-line tester is made to exact specifications and is self regulating and actually learns.

Detecting micro leaks took 48 hours using the old fashioned squeezing method, now the Oxipack method detects leaks immediately after packaging.

The equipment pays for itself
This accurate in-line leak detection based on pressure measurement results in the percentage of leaks being markedly reduced. Moreover, the pallets no longer have to be stored for 16-24 hours. This reduces stock held and benefits working capital. Also less storage space is needed. In addition the packs do not need to be checked for leaks manually two or three times. This saves considerable in handling costs. In short Oxipack’s in-line leak detection makes the production process much more efficient.

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How do we reduce the percentage of leaks?
This percentage can only be reduced if the exact figures are known. When trying to optimise efficiency a proper analysis of the actual percentage of leaks is vital. Actually finding out how many leaking packages are being produced is difficult to do.
Closer, critical investigation shows that the percentage of leaks is always greater than expected. All kinds of factors play a part and views on leak detection vary. Nobody wants to stop a production line, but the consequence further down the line, is that large numbers of packed products will need to be destroyed.
Attack the problem at source: the packaging machine. If you know exactly how many leaking packages are being produced then you will very quickly have the packaging machine under control and the percentage of leaks as well. Systematic leaks can be traced using systematic sample testing. Random leaks can only be detected using 100% leak detection.

What savings can be made with leak detection?
Leaking packaging always causes losses in the whole production chain. Which might even damage your brand reputation. Leak detection however is a tool that results in savings.
Savings of one to two tonnes in euro’s for each packaging line per year are possible in the food products sector. The calculations vary according to circumstances and depend on the product and raw materials used. Is the current packaging destructively tested for leaks? If so the savings are even greater.

Would the number of staff needed, change due to in-line leak detection?
When using 100% leak detection less people are needed for final checks. The operator spends less time on checking and has time to deal with other tasks. The leak detection equipment results in no additional stoppages due to maintenance.
In the first few weeks the equipment will regularly detect leaking packaging. It will look like more packages are being found with leaks than before. The cause of the leak will have to be traced in order to solve the problem with the packaging machine. The Production Manager should take this into account. After a couple of weeks the packaging process will have improved so much that leaking packaging will only be detected once in a while. And that is why you chose for in-line leak detection.

Is 100% leak free packaging possible? No, it just is not possible. There will always be tiny leaks and it is hard to predict where and why they occur.

  • It could be a random event, when the product just happens to come into contact with the edge of the seal.
  • Other leaks develop systematically. Then every twelfth package has a leak, a whole pallet or a certain corner of a seal. There could be a small pip on a roller that the foil runs over. Or perhaps one of the twelve sealing jaws in the vacuum applyers does not heat properly.

Are there more packages leaking than before?
The “lean” production methods in the food processing sector seem to increase the number of leaks. Stocks are kept to a minimum. In the past, the same product would roll off the production line continuously for a whole week, now the same packaging production line will switch between all sorts of flavours and umbrella brands. Due to this change the production line does not run continuously. After a few shifts the packaging machine is converted to produce packaging using other paper covers or a single foil wrapper. This could be for another country or subsidiary brand.
As a result of lean production methods the machine has to be restarted a few times every week. And the start up process normally entails a run with a series of leaking packages. As the packaging production line has to get up to speed, the sealing process takes longer. This means the product material is exposed to high temperatures for a longer period. This results in a higher percentage of leaks.

How long does it take to recoup the investment? The answer depends on another question: what does leaking packaging cost the company?
Is this difficult to find out? Just ask yourself this:

  • What does it cost if a production run of 12 hours has leaks?
  • And what is the cost of four hours production for repackaging?

The investment in stand alone leak detection can be recouped in a few months.
In-line leak detection equipment pays for itself in one to two years.
It can sometimes be hard to present a business case if you do not have the exact figures relating to down-time or leak percentages. We can help you with the calculations.

Is it a dry measurement method?
The Oxipack leak test equipment works by measuring pressure. Water is not used in this process and no detection gases are used. It is a clean, dry and extremely precise test method. This applies to both the stand alone leak testers and in-line leak detection systems. This form of testing allows you to get rid of the not so hygenic water immersion tank from the production area.

Can the stationary leak tester be used continuously?
Need to check large quantities of packaging at a high speed? The Oxipack testing equipment is ideally suited to this purpose. The Stationary Leak tester can be deployed for offline testing in a lab situation or for random sample testing during production. Where necessary, it can run continuously.

What does in-line leak detection mean for the operator?
Introducing 100% leak detection demands some extra work from the operator initially. The first weeks will be more demanding; the system will detect leaking packaging more often than expected. That means the operator will have to trace what is causing the leaks. The operator will also have to handle the rejected packaging. Once the packaging machine has been set up for optimum performance, the number of leaks in the packaging will drop sharply and things will be easier for the operator.

Is it difficult to operate the stand alone leak tester?
Quite the opposite, operating is simplicity itself. Open the cover, put the packaging in, close the cover and press the green button. The equipment does the rest. If the green light comes on, that means the packaging has no leaks. If the red light is on then the packaging has a leak. A simple but a reliable test method.

How often does the leak tester break down?
Almost never. The Stationary Leak Tester is a robust device that can handle 500 to 1000 leak tests a day. Breaks downs are very rare. Most importantly the leak tester needs very little maintenance. An occasional clean with a damp cloth is all that is needed. An annual service is sufficient to check the condition of the membranes and filters.

What do operators think about working with the Stationary Leak Tester?
Operators can carry out their work to an optimum level with the Stationary Leak Tester. The fact that this is a “dry” test method is greatly appreciated. This is certainly true if the operator works in a chilled environment. We often hear operators say:

“it’s ideal, I no longer have to put my hands in the immersion tank, this equipment is excellent”.

Because people like using the equipment, the method for taking measurements is made use of in the agreed way.

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