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Companies running shrink wrappers, effectively the 4x4s of the packaging world, have most to lose when soaring gas and oil prices send utilities bills on an upwards trajectory. Steep rises are hard enough for domestic users to stomach, but for packers and processors, running energy-intensive machinery 24/7, every price hike deals a stinging blow.

Shrink wrappers are one of the worst offenders when it comes to energy consumption. Shrink tunnels consist of a heat delivery system with an insulated chamber through which the product is passed on a conveyor. Although the amount of energy they consume depends on the film thickness, the size of the item being wrapped and the machine speed, it is usually somewhere between four and 10kW. While this is a massive improvement on the hulking machines of a decade ago, which typically required 15-20kW of energy, it is still a lot of watts. And as energy prices increase, it begs the question of how much longer packers and manufacturers will sit back and absorb these costs.

At this year’s Total exhibition, PPMA consultant Martin Keay identified cutting energy consumption as a key target for today’s machinery designers, in an effort to address cost and environmental concerns. But do these predictions reflect what is happening, or are buyers too concerned with the capital cost of a machine to worry about its running costs or green credentials?

“Customers do ask for consumption figures when buying equipment, which they didn’t used to, so there has been a slight change,” says Mark Parminter, managing director of shrink and stretch wrapper specialist Inpac. “But they still don’t make a machine decision based on energy consumption. I think in terms of priorities, price is probably near the top while energy consumption ranks somewhere near the bottom.”

Meanwhile, Peter Frith, managing director of Shrinkwrap Machinery, says: “Energy consumption is one of the many concerns of customers and is moving up the list of priorities. Aside from the usual concerns of cost, reliability and service, customers are increasingly aware of green issues, such as film type and waste and the cost of alternative types of packaging.”

So, for those companies keen to invest in an energy-efficient shrink wrapper, what products are available?

According to Parminter, not many at present. “These things require a lot of time and effort to design, and that kind of investment in R&D is expensive.”

Much of the innovation to date has come from the film manufacturers rather than the machine manufacturers.

Sealed Air, for example, can offer customers low-energy films such as Cryovac D940, Cryovac Adapt or Cyrovac D955 11 micron, which allow users to work at lower sealing and shrinking temperatures.

Turning down the heat
But equipment suppliers argue advancements have not just been limited to the films. All the machines in Sealed Air’s new Shanklin series have a ‘relaxed’ mode when not in continuous use. The internal tunnel temperature is lowered by up to 35% as soon as the sealer is relaxed, cutting energy use while keeping the equipment ready for production to start again; the energy needed to bring the temperature back up is less than the energy required to completely reheat the tunnel from the off position.

At Adpak Machinery Systems, sales manager Tony Roberts says the firm is “turning the temperature down” by 20-30°C compared with 10 years ago due to advancements in both the film and the tunnel.
“We’ve got a new generation of shrink tunnels – the AD 450T and the 650T – that has halved energy use to just under 7kW. They are very compact and are also ‘cool wall’, which means that when you touch the outer casing, the metal shroud around the tunnel is cool to the touch so the heat is kept in the tunnel rather than escaping through the walls. That is due to improvements in technology on the heating element and insulation side.”

Shrinkwrap Machinery, meanwhile, has delivered five bespoke shrink wrapping machines to Huhtamaki (Lurgan) in Northern Ireland, which have allowed the speciality packaging company to reduce the size of its shrink tunnel.

“Tunnels work most efficiently when matched to a product’s size and with only small gaps between the products, ie 75mm,” explains Frith.

The machines completed a re-engineering project of nine lines for wrapping moulded-fibre egg cartons.
Huhtamaki commissioned four 1,100mm-wide dual-side-entry machines and one 900mm-wide single-side-entry machine. The dual-entry machines allow product from two lines to enter the machine.

Different width films – narrow on the bottom and wider on the top – are used. The excess film at the sides of the packs is lifted from the bottom and lowered from the top before side sealing. This enabled the shrink tunnel to be reduced in size to cater for packs of up to 1m long, 600mm wide and 350mm high using a film thickness of 25micron. The shrink tunnel uses thermal transfer barriers with bottom air recycle and thick insulation.

Other improvements
Another player, Aetna UK, says it has made its equipment more energy efficient in a number of ways, including higher thermal insulation to reduce heat loss from the tunnel, better air circulation inside the tunnel to increase the efficiency of the shrinking process, and the ability to run lighter and thinner films. Automatic start-up and shutdown of the tunnels prevent it being left on when not in use, but at the same time ensures it is switched on ready for production.

The company’s chairman Barry Tucker also says it is quoting for customers that want to move out of shrink wrapping into stretch wrapping because it is a ‘cold’ process, for items like doors, light fittings and kitchen units.

Packer has just launched a new range of stretch wrapping systems, including a compact system and two mobile systems.

The PSW/JFM compact stretch wrapping machine features a piston-designed, film-carriage system that is said to reduce moving parts and improve reliability. The machine has a compact footprint, which Packer says makes it ideal for mezzanine areas where there are height restrictions.

The MSW/M mobile stretch wrapper, meanwhile, is mechanically driven so it doesn’t require an electrical supply, leaving it free to be manoeuvred around pallets. Packer says the device is also one of the few on the market that can wrap within 60cm of a pallet, allowing its use in areas where space is limited.

A semi-automatic system from stretch wrapping equipment specialist Orion Packaging Systems has allowed an Avonmouth-based supplier of agricultural seeds to save costs and enhance pack presentation.

At British Seed Houses, bags of seed weighing 12-15kg are loaded, up to 50 at a time, onto pallets, for delivery to wholesalers and retailers across the UK.

The palletised loads are wrapped to protect against damage during transport and from the elements. Wrapping was being done by hand, but this was not only using a lot of film, but was not achieving a tight enough pack and was taking up a lot of staff time. So the company contacted Orion to recommend a more automated approach.

Orion supplied an LP500 semi-automatic stretch wrapper with powered pre-stretch of up to 300%. The machine is now wrapping up to 50 loads per day.

Tighter alternatives
Another energy efficient alternative to shrink wrapping is ‘tight wrapping’. As well as offering shrink and stretch wrappers, Bradman Lake Group, through its Europack brand, manufactures a range of tight wrappers, varying from semi-automatic hand-fed machines through to fully automated systems with a variety of built-in collators. Models are available with side-fed and in-line configurations and with a number of different sealing jaw widths.

“In tight wrapping, the film is applied to the product so that it just fits without actually applying any tension. This is achieved primarily by the geometry of the sealing jaw,” says the company’s Tracey Parnell, explaining the difference between tight wrapping and shrink wrapping. “As less film is applied, less heat energy is required to shrink it. This, coupled with improvements in shrink tunnel design, has resulted in smaller, more efficient heat chambers.”

However, Stephen Booth, director of shrink and over wrapping machinery supplier Burnley Packaging & Oakwell Packaging, has concerns about the limitations of films that can be used by tight wrappers and says they are reputed to be higher maintenance than traditional sealing units.

In response, Parnell says materials for tight wrapping are, like traditional shrink and stretch wrapping, often polyethylene based, and that maintenance for these machines is no more complicated than for other wrappers.

Nevertheless, Booth concludes: “We see the future in over wrapping equipment, which can use more flexible films that are starch based, or cellulose for many lighter applications, but shrink wrapping will always have a future for heavy products like cans and bottles.”