Seal and Shrink Wrap Machinery

by Richard Jankel

Published on this site: August 21th, 2006 - See more articles from this month

Shrink wrap equipment consists of an L-sealer with an enlarged base to store a fan together with heaters, the whole topped with a plastic see-through hood. When the machine is switched on, the heaters build up a store of heat which is utilised when the machine is cycled. As the hood, which incorporates the
L-sealer, is closed, the heaters are uncovered. At the end of the sealing cycle, the fan is engaged to circulate heat around the pack. The operator can choose a seal only function.

This particular configuration of equipment was first brought to market three decades ago. At that time, the conjunction of a shrink function contained within the body of a sealer was protected by a patent. As a consequence, supply was restricted.

At the same time, the machines were not as sophisticated as they are today in terms of performance, whilst the market demanded machines with greater output. The desire for faster production speeds had as much to do with the limitation of running PVC shrink film at speed as it did with the relative lack of sophistication of conventional manual, semi and fully automatic machines.

The seal and shrink wrap equipment, conventionally called a Chamber machine, suffered then and continues to suffer now from an inherent inability to produce at a particularly fast rate. One must consider that whilst the seal time for film is in the order of one second, the shrink time for any pack is in the order of four to five seconds. When one adds the feeding and unloading time, one inevitably sees a total cycle time in the order of ten seconds. Hence one must consider output limited to a maximum of six packs per minute. Generally, a speed in the order of four to five packs per minute only, should be considered.

Historically, the consequence of the speed restriction caused Chamber or Bubble machines to achieve only a certain market presence. Users were instead pre-occupied with high speed and necessarily high value and high complexity equipment. However, the penetration of these machines precipitated the reconsideration of the value of having good performance from low cost, easy to use machinery with zero set up time.

Over the same period, the Bubble machines improved in their ability to offer consistent seal and shrink on all available shrink wrap films. This latter attribute has come to the forefront particularly in the last few years where Bubble machines have been specifically built to perform well on the latest generation of polyolefin shrink films.

As a consequence, over the last several years, Chamber equipment has found an increasing presence in the market. Customers appreciate the very low physical size, the ability to position the machine anywhere, the very low acquisition and running costs and versatility of output.

As a consequence, the market for Bubble equipment is particularly buoyant. Users look for a variety of attributes -in particular, the ability to work with sophisticated shrink wrap films and the ability for the machine to work consistently at a high level of pack quality - this is a function of the design and build quality. One should seek robust construction combined with good digital control features offering a complete range of appropriate programme settings.