Heat Sealers: Lean can be green

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In 2008, before the economy went into meltdown, it looked as though ready-meal heat sealers were on the cusp of a green revolution. The key players in the market had diverted their R&D efforts from new sealing technologies, like radio frequency and laser sealing, to making their heat sealers more economical on film usage and energy consumption.

Packaging Automation in Cheshire, for example, launched a patented tray sealer called the Eco-Cut, which was said to reduce film waste levels by up to a third.

Two years on, the tough economic climate has forced many in the sector to rethink their priorities, pushing environmental considerations down and cost considerations up the agenda.

"People don't really ask about film wastage when buying new machines," says David Edwards, managing director of D2 Food Systems. "The main focus of our customers in the last couple of years has been capital outlay and running costs."

James Causebrook, sales manager with Grunwald UK, a supplier of high volume, turnkey ready-meal packaging lines, agrees that environmental concerns don't really come into the purchasing equation. "We're not looking at improving the eco-credentials of our machines as it's not something our customers are asking for."

Packaging Automation also seems to have changed direction with its R&D to reflect the fact ready-meal producers have more than just environmental concerns on their minds. At Foodex Meatex in March, the company is launching its Eclipse heat sealers, which, it says, "further develop the technology introduced in the Eco-Cut machines for energy and materials savings".

"Eco-Cut has performed well but we think the Eclipse range will do even better as we have taken the innovation introduced with Eco-cut to design a rugged and reliable machine that gives the market greater speed, flexibility and cost savings," says sales manager Neil Ashton.

"Ready-meal manufacturers are always looking for more cost-effective methods of producing their products. They have already reduced the cost of ingredients and cut packaging costs by running thinner-gauge films and lighter trays. Now they are primarily looking for reduced costs through line efficiencies; in other words, higher speeds and less downtime," says Ashton.

Efficient operation
That said, the Eclipse uses a new method of generating the seal force that is said to use less air, resulting in cost and energy savings. Plus it features an auto-sleep mode, which kicks in when the machine is not operated for a given period.

Ready-meal producers may be more cost focused at present, but Packaging Automation reports that they want to be able to run biodegradable, environmentally friendly materials. So what challenges does this introduce for the sealing operation?

"There is no problem with rPET per se," says Ashton. "The problem arises when a customer wishes to seal it to an incompatible tray substrate." Packaging Automation has been running trials on these new materials and says it has built up a database of films and tray substrates to identify which are compatible and can be sealed successfully.

Grunwald has also observed that quite a few of its customers are moving to rPET, cardboard and biodegradable packaging. "One of our machines has been running rPET film for about nine months now with no reported issues," says Causebrook. "As long as the film material is compatible with the tray we can create a good seal."

He says the only difference when working with rPET is that the ‘sealing window' is slightly smaller. When creating a heat seal, there are three settings that you have to get right to achieve seal integrity. These are pressure, time and temperature. With most conventional materials, there is plenty of latitude on these settings. However, with rPET the tolerances are much tighter.

"When you go to rPET, you might have a sealing window of, say, plus or minus 25°C and the time is quite critical. We tend to seal slightly cooler than we do with other films and apply the seal for slightly longer so we can increase the pressure - we find increasing compression rather than heat results in a better bond."

Not all equipment manufacturers believe ready-meal producers have gone cool on environmental issues. Proseal sales engineer Rick Carless, for example, says: "New customers' main concerns vary depending on each company's philosophy but most are now leaning towards the eco-credentials of the equipment."

Proseal has developed a patented system called EcoSeal, which is said to reduce the machine's total energy consumption by more than 65% while at the same time increasing the seal force by 190%. "This ensures the seal integrity is maintained throughout the distribution and retail chain," explains Carless.

Proseal is currently in the process of applying for Carbon Trust approval of the EcoSeal system. But the company recognises that eco-credentials alone are not going to sell machines in the current climate. "Other key requirements remain fast throughput and quick changeovers for the highest throughput and minimal downtime, and compact footprints to maximise factory space. With the variety of tray formats and sealing substrates, machine flexibility is also vital," says Carless.

It's clear from what equipment manufacturers are saying that reducing the costs associated with heat-sealing equipment is of paramount importance to ready-meal producers. Most equipment designers are making their sealers more economical by focusing on minimising downtime, for example, by reducing changeover time between different materials and container shapes and sizes and reducing the time needed for cleaning and maintenance.

Two-minute tooling
Proseal has developed an ‘Auto Tool' facility, which is allowing tool changes to be carried out in two minutes at RF Brookes, part of Premier Foods. The firm ordered four automatic GT1 heat sealers from Proseal after expanding its range of chilled ready-meals.

On Packaging Automation's Eclipse machine, tooling changes of two minutes are said to be achievable. Downtime has also been reduced by a new film feed system that can run lower-gauge film without snapping and by a system that identifies trays that have been incorrectly fed into the machine, preventing smashes.

Grunwald says two-minute changeovers are the norm on its Flexliner machine. "This is achieved by holding the containers with laser-cut format plates; the distance between the plates adjusts at the press of a button to hold the new container size," explains Causebrook.

In addition, Grunwald says that it has cut maintenance costs by reducing the number of component parts in its reel feed assembly and by making its chains more durable. "We're getting durability of about 10 years on our drive chains, whereas some of our competitors change theirs every two years."

Mecaplastic has just launched the Double Step range of automatic tray sealers, whose quick-change tooling system allows tools to be changed within less than 10 minutes. In addition, the tooling is interchangeable between the smaller and larger machines in the Double Step range, so when a company wants to upgrade to more advanced equipment, it doesn't have to invest in a complete set of new tooling.

Ishida's QX-1100 tray sealers, usually installed as part of an integrated ready-meal packaging line, are said to offer great flexibility through an operator-friendly interface, fast changeover times and a hygienic design for speedy cleaning between product changes. The filling interface is a one-button operation to change a product recipe, which Ishida says saves valuable set-up time.

D2 Food Systems, meanwhile, has responded to the more cost-sensitive marketplace by making its tray sealers more simple. "We've been designing out the complication from the machine and through that simplicity we have achieved greater reliability and lower cost," says Edwards.

Interestingly, building tray sealers that can run at breakneck speeds doesn't seem to be an objective for most equipment suppliers. "Our machines can meet the speed requirements of the market - whether for 10 or 100 trays a minute - and we don't see any need at present to produce faster machines," says Edwards.

According to Proseal's Carless, the reason ready-meal operations rarely require top-end speeds is due to the complexity of the recipes. There is, however, a requirement for faster machines where MAP is being used, as this slows the sealing cycle down, says Edwards. "MAP is becoming more widely used in ready-meals and we're looking at improving the speed of the MAP cycle by eliminating the vacuum and using pure flush systems which use less gas."

Proseal says its system does not need to pull a vacuum before flushing, and by removing one of the component parts of the sealing cycle, much higher speeds can be achieved.

Ilpra UK, meanwhile, has developed a feature called Progas for its MAP-ready tray sealers. "Without using either a bigger pump or customised mould, this system allows customers to achieve high performance and higher output and save as much as 40% on MAP gas usage," says company director Brian O'Donoghue.

Green issues, it would seem, are not necessarily off the agenda. But they sit alongside the economic considerations of quicker makeready and run speeds.

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ECO-BAND CHALLENGES CARDBOARD SLEEVE
An alternative to cardboard sleeving promises to reduce packaging waste by more than 50%.

Supplied by Erapa in the UK, the BandAll band applicator is designed to wrap paper or plastic bands printed with product information around ready-meal packs.

Unlike cardboard sleeves, bands do not have to be pre-made to a fixed maximum size to compensate for manufacturing tolerances. Instead, every band is automatically applied with the same tension around the pack, eliminating band movement and improving presentation, says Erapa.

Erapa supplies both the band and applicator. Bands are supplied in reel form, and can be pre-printed in 29mm, 48mm, 75mm and 100mm widths. The band applicators range in size and sophistication from simple, hand-fed machines to in-line systems complete with printing of bar codes and best-before dates.