Stretch Hooding and Shrink Hooding are common methods of packaging palletized products. Stretch and Shrink hoods can provide load stability and protection from dust ingression or infestation.
Shrink & Stretch Hooding: Comparison of Films and Machinery
Shrink Hooding involves applying a heat shrinkable, gusseted polyethylene bag to a pack and shrinking it to the pack using hot air emitted from gas burners (LPG or natural gas).
The flame on modern machines is only ignited during the shrinking operation. This saves energy compared with earlier technology, where burners on some models were on during the whole production shift, regardless of operation. Modern machines also use enclosed hot air burners. The burners on some older models are not enclosed, therefore if the hood is poorly positioned the flame can come into contact with it, causing the pack to catch fire.
Stretch Hooding involves applying a stretchable, gusseted polyethylene bag to a pack, but without using gas burners. While shrink film consists of a single layer, Stretch Film is a 3 layer co-extruded film. With both systems gusseted film is supplied on a reel. The machine draws the desired length of film from the reel, welds and then cuts to form the hood. The hood is then lowered over the pack until the machine releases it at the desired position (often at conveyor level).
Advantages of Stretch Hooding
Stretch Hooders do not use gas burners, which has the following benefits:
Furthermore Stretch hooding uses 25-30% less film per pack than shrink hooding to wrap the same product (based on the same gauge of film) due to the stretching process, which means less packaging waste.
When the two technologies are compared in this way, it is understandable that many companies are looking to replace their Shrink Hooders with Stretch Hooders.