Introduction to Shrink Wrapping Machinery

The shrink wrapping process involves two stages: wrapping the package in shrink wrap in whole or in part and applying heat to the shrink wrap film that activates the material's memory of its unstretched molecular chains.

The shrink wrap application can be divided into two main types: transit and display.

Transit

The purpose of transit packaging is to offer the lowest cost packaging option. The material used is almost exclusively polyethylene, which will provide adequate strength at the lowest available cost. A typical application is sorting individual packages with or without tray support. The most frequent use of the above involves packaging a quantity of cans or bottles or cartons for distribution.

The equipment used includes a sleeve or package sealer that works in conjunction with a shrink tunnel. Two rolls of material produce a film sleeve around the package, which is then processed through the tunnel. Generally, these open sleeves do not cause any disadvantage in the integrity of the package, although a modification can be made in the tunnel whereby an attempt is made to close the hole through the excess annealed film.

A considerable amount of automation is offered for this process so that a full range of manual, semi-automatic and fully automatic sealers can be found and, at maximum throughput, lines with speeds of up to 200 packages per minute can be found.

Polyethylene processing is distinguished by the need for the shrink wrap film to reach a near melt state, after which cooling will provide significant additional automatic shrink packing machine. As a consequence, tunnels require specific cooling devices if high exit speeds are required.

All of this equipment can be used to wrap individual packages where bundling is not required but some degree of protection is needed. Applications can range from radiators to office doors to fabric bolts.

Monitor

Identical processes also apply, but with display shrink film where products have a natural requirement to use a sleeve. Rolls of wrapping paper and wallpaper fall into this category. The principles remain the same, although both the sealer and the tunnel will be modified to accommodate individual rolls with appropriately small diameters.

As for conventional display applications, the main feature is the use of a full wrap.

In all cases, the sealer should now create a flat, two-dimensional pocket around the product.

The product and this bag are then processed through a shrink tunnel to achieve the desired effect.

At the most basic level, this is achieved using an L-Sealer and dubbed film. The product is manually placed between the two layers of film and again manually placed into the sealer. The seal is completed and the package is placed on the tunnel conveyor. This is a continuous process that also produces a waste film element.