Shrink Wrapping Machinery Glossary – The Terms You Need To Know!

Shrink Wrapping Machinery

Are your side sealers mixed up with your sleeve sealers? Don’t know a double chamber tunnel from a single?

We know it can be challenging to understand the jargon if you have never used a shrink wrapping line before. That’s why we’ve penned this handy guide to all things machinery-related!


Collation – A collation is an arrangement of several products that need to be shrink wrapped together in a specific layout without a tray e.g. boxes in a 2 x 3 format or bottles in a 3 x 6 format. Some shrink wrappers are specially modified to take multiple products one by one from a single lane conveyor and then use pushers to arrange them into pre-programmed collations before they are wrapped.

What is a Combination Unit? – This equipment is unlike all the shrink wrapping lines discussed below because both the sealer, in this case an ‘L’ sealer, and shrink tunnel are incorporated into one unit.

What is a Double Chamber Shrink Tunnel? – A double chamber tunnel is considerably longer than a single chamber tunnel and is used for high speed packaging applications. If speeds are higher, less time is spent by the pack inside the shrink tunnel which therefore affects the quality of the film shrinkage. By doubling the size of the unit, the pack spends longer time being exposed to heat inside the tunnel and ensures a tightly shrunk pack is still achieved.

Guarding – This term relates to the parts of the machine that are in place to protect the operators. It encompasses shields or covers for hazardous sections of the machinery to prevent contact with body parts and injury. At YPS we always guard to our customer’s own guidelines for health and safety and as standard our guarding far exceeds the minimum requirements set by CE marking regulations.

What is an L Sealer? – So-called because of it’s ‘L’ shaped sealing frame, this machine uses centre-folded shrink film. One layer of film sits above and one layer sits below the product. The sealing frame comes down around the pack to seal two sides, creating a bag. As the products progress through the machine, the sealing frame will come down to bag the next product and in doing so will seal the side and last edge of the previous pack. This machinery is typically used for display applications and is available in semi and fully automatic models.

Pneumatic – This refers to a system which uses air to provide a physical force. Examples of pneumatic technology on our shrink wrapping machinery are ‘pushers’ which are arms that push each product in turn into the wrapper or ‘sealing jaws’, which come down in turn between each bagged product to seal it separately from the next.

Servo – A servo is a control system which allows precise movement of motors for accuracy and speed. This technology is an upgrade from pneumatic technology.

What is a Shrink Tunnel? – Tunnels, either double or single chamber, are separate machines that complete a shrink wrapping line and come after the sealing unit. Their purpose is to tightly shrink the film that has been placed around the products in either the bags sleeves or tubes as just described. This is done with heat which reacts with the film to make it shrink down. The use of heat sometimes leads to these machines being called shrink ‘ovens’.

What is a Side Sealer? – A side sealer uses centre-folded shrink film opened up with the product sat inside, surrounded by three open sides. The machine sealing bar seals the sides which then creates a ‘tube’ of film around the product. As the products then progress through the machine, the back of the pack is ‘cross-sealed’ through the action of the sealing bar coming down to separate one product from the next. Side sealers give a totally enclosed pack and usually give a tighter bag than ‘L’ sealers. They also operate at faster speeds than other models. A key feature of side sealers is their ability to wrap products of unlimited lengths, whereas ‘L’ sealers are restricted to the frame size.

What is a Single Chamber Shrink Tunnel?– This term refers to the size of the ‘oven’ area of the shrink tunnel, between the infeed and outfeed belts. A single chamber is the standard size, which allows the film around most packs to be exposed to the heat for long enough as it moves through to shrink down neatly and tightly.

What is a Sleeve Sealer?– These machines utilise two single-wound shrink film reels, one sat above and one sat below. The machine seals the film layers together on each side, effectively creating a ‘sleeve’ with two open ends, hence the machine’s name. A typical product that would be wrapped on a sleeve sealer would be a multi-pack of water bottles. This equipment is predominantly used in transit applications.

Trayed – This terms relates to products that have been pre-arranged into a cardboard tray before being pushed into the machine to be wrapped.

Trayless – Collations of trayless products, without cardboard trays, are randomly fed and then pushed into pre-selected combinatinations to be fed into the machine and wrapped.


Are there other shrink wrapping machinery terms that you don’t understand? Submit them to us today at and we will add them to our glossary!

Do you want to wrap up your knowledge of shrink film terminology too? Find our comprehensive glossary here.