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  • Shrink Wrap Machines – The Top Five Myths Debunked!

Shrink Wrap Machines – The Top Five Myths Debunked!

We think it's time to wrap up some of the most common myths we hear in the packaging industry once and for all! 

Myth 1: ‘You can’t shrink wrap irregularly shaped products.’

Fact: You definitely can shrink wrap these products! However, there are two issues that need to be considered to achieve consistent results. 

The first is ensuring an accurate pack detection by the shrink wrapping machine, in order to trigger the placement of film around the product. On a standard shrink wrapper, each separate product is detected with a beam of light as it travels into the machine. When the beam is broken, the equipment knows that one product has fully passed through.  Let’s now imagine an egg box, a rather irregular shaped item without square edges and flat sides. In this instance, on a standard machine, the beam of light would reconnect in the gaps between each egg. The shrink wrapper would therefore incorrectly interpret half-way through the pack as the end of the pack and would try and seal it too soon. The action of the sealing jaw coming down on the product would then trip the machine out. 

To overcome this, we can offer shrink wrapping equipment that is specially adapted to irregularly shaped items. One feature is our multi-pack detection which is programmed to compensate for the gaps, dips or troughs in a products dimensions. 

Another way around this problem is to use a light curtain instead of a beam of light. For example, we completed an installation at leading outdoor buildings supplier Kybotech, who were wrapping multi-packs of wood pieces in different lengths, shapes and sizes (see video footage below). For this application, we utilised a light curtain; a solid, thicker beam of light. If only a part of the light curtain is broken but remains constant elsewhere, the equipment knows that the product is still passing through and will not dispense shrink film.

The second important consideration is the performance and strength of the shrink film being used. Irregular shaped items can have sharp edges or corners and the film must be durable enough to prevent piercing from these. Our shrink film experts can recommend a suitable puncture-resistant film for these products that does not compromise on aesthetics or performance.

Furthermore, the shrink film used often needs to be burn-resistant. Irregular shaped items inside shrink film will have gaps and air pockets, unlike geometric shaped packs. As the packs enter the shrink tunnel, where a combination of heat and air flow serve to shrink the film tightly around the packs, the air trapped inside heats and expands. This process can result in burn holes and scorching damage. Our range of film includes pre-perforated options, which have tiny holes allowing the expanding air to escape from the pack and therefore avoiding burns. 

Myth 2: ‘You can’t shrink wrap unstable products.’

Fact: Again, shrink wrapping unstable products is absolutely possible in a number of ways! 

To increase stability of packs, secondary packaging like cardboard trays can be utilised for products that are unsteady when collated, offering a flat and square surface to the bottom of the packs for rigidity. 

Bagged product, such as sacks of bird seed, could be unstable when stacked on top of one another and wrapped as one. Our collation devices can achieve this by ensuring weight is evenly distributed as they are stacked.  

However the principle way to ensure stability of unstable products is to slow the wrapping speeds. Drinks bottles are a classic example of products that can wobble and topple over. In a collation of 24 bottles for example, even one collapsing item could cause chaos on a production line! By slowing speeds down, accuracy and control can be totally guaranteed.  

Myth 3: ‘You can’t shrink wrap non-rigid products like calendars because they will curl up and bend.’

Fact: At YPS we have completed many installations at print companies wrapping products of this nature and use three methods of ensuring best-in-class pack presentation, specifically for non-rigid products.

The first is the addition, at minimal cost, of cardboard stiffeners to the packs being wrapped. They can be inserted at intervals into products like packs of paper to help keep their shape. This is very common with calendars in particular.

Secondly, the use of low energy shrink films stops bendy items from becoming misshapen and rolling up. These films stop the shrinking process at a much earlier stage of resistance to the product than standard specifications of shrink film. The lesser amount of energy in these films means that they have less shrink force whilst delivering the same shrink ratio.

Finally, we can quash worries about non-rigid products with the addition of a flat pack roller device to the shrink tunnel. This is a series of rollers that sit directly above the tunnel belts as the packs are transported through, making it physically impossible for the shrink wrapped products to curl up. 

Myth 4:  ‘Food that melts or spoils, like dairy products or chocolate, isn't suitable for shrink wrapping because of the heat in the shrink tunnel.’

Fact: YPS supply shrink wrapping to a huge variety of food and drink companies across the U.K., including to producers and distributors of perishable foodstuffs. The particular concerns around items that need to remain cold like chocolate, ice cream and milk are understandable because the shrinking process applies heat, but these concerns are unfounded.

The reality is that the length of time packs spend inside the shrink tunnel, only a matter of seconds, is so short that there is no effect whatsoever to the food.

Furthermore, the shrink film plays a role in protecting the food as it absorbs the majority of the heat in order to carry out its function of shrinking.

Myth 5: 'Shrink wrap is always plain and clear.’

Fact: In fact, shrink film can be supplied in any colour with the use of additives in the manufacturing process. In addition; if the film is treated with a special ‘corona’ treatment, complete full colour printing can be achieved with any image or logo.

Yorkshire Packaging Systems, always at the forefront of our industry, can now supply printed films for a multitude of applications. Comprising of high definition flexographic printing, possibilities for this shrink wrap include continuous or discontinuous print and surface or reverse print, with up to 10 colours or colour combinations available.

Whilst there are many benefits to the traditional clear shrink films, including maximum visibility of the wrapped product and an eye-catching shine for pleasing optics, the opportunities opened up by printed films are impressive.

Enhanced branding, increased product information visibility negating the need for labels and printed inserts and the anti-counterfeit properties all mean that printed film offers a way for your packaging to work harder for you!  

If you have heard a shrink wrapping claim that you’d like confirming or debunking, email us at enquiries@yps.co.uk today to get the facts! We will share your query in our next instalment! 

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