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Induction heat sealing provides flexible hermetic seals.

The use of induction heat sealing techniques (IHS) to create hermetic seals on a wide range of plastics and glass containers is becoming increasingly popular in the food processing industry. One area which is experiencing particular growth is the dairy industry, where IHS is being applied to prepared milk products, primarily to improve product presentation and reduce the problems of leakage during transit. Additionally, other liquid foodstuffs, such as fruit juices, bottled water, sauces and syrups can benefit from this sealing process, which can be implemented without affecting line speeds or other operating conditions.

Typically, the plastics containers used in the packaging of dairy and other liquid or semi-liquid foodstuffs are relatively thin walled. With standard clip-on or screw caps, any twisting or vibration of the container, for example, during transit or warehouse handling, can result in distortion at the neck, creating leaks.

Induction heat seals eliminate the problems of leakage as the seal on the neck of each container flexes when the pack distorts. They will withstand considerable impact, allowing containers to be dropped from heights of several feet without damage. Additionally, the seal forms a tamper-evident barrier and, of course, maintains product freshness.

The induction heat seal is constructed from a multi-layer material, which comprises a aluminium foil disc wax bonded to a support layer - typically pulpboard - on one side and coated with a polymer layer on the other. The seal is fitted into a plastics cap, which is applied to the filled container and |torqued down'.

Each container is then passed under an induction heating coil or through a tunnel, which generates an electro-magnetic field. This creates a low level of localized heat in the foil membrane, which melts both the wax holding the foil to the support material and the polymer layer on to the neck of the container. As the container moves away from the electro-magnetic field it cools and the polymer bonds the foil to the neck of the container.

When the cap is removed by the consumer, the support material remains in the cap, where it acts as a secondary seal once the foil has been punctured or removed.

Until recently, IHS could leave a foil residue around the neck area, making it difficult to recycle containers. To overcome this problem, a new generation of peelable seals is now available, which the consumer can remove completely, yet this peelability does not affect the integrity of the seal.

Typically, IHS systems offer little or no room for error. Process settings must be exact, as the slightest deviation from the correct setting can result in problems that generally relate to uneven or excessive heating in the foil disk.

Poor induction is often caused by the use of incorrect operating frequencies. Outputs are often set at levels -- typically above 100kHz -- at which the current, and hence the heat which is induced into the foil, is difficult to control.

To resolve these problems, low frequency systems have been introduced. These operate at around 30kHz, enabling the current flow in the foil to be controlled closely and ensuring that heat is distributed evenly across the material, to create a proper seal. Additionally, the introduction of low frequency systems has enabled the operating range in which an effective seal can be produced, to be expanded dramatically. Factors such as dwell time and the distance between the sealing head and the neck of the container are no longer so crucial.

Ineffective or burnt seals can also be caused by the containers passing under the sealing head at irregular intervals. As a solution to this problem, the latest IHS systems incorporate automatic feedback controls. These operate by detecting the loading imposed by individual containers and by monitoring changes in the output frequency caused by the presence of each foil seal. This automatic feedback control uses this information to limit the output power to suit the load variation and production line container flow.

Other factors, that should be considered, include the type of polymer coating which must be formulated for containers being used, the quality of the container itself, in particular the finish around its neck area, and the fit of the seal within the cap.

Correctly designed and maintained IHS systems can greatly improve pack and product presentation. Compared with other methods of sealing, they represent a cost effective and relatively simple method of producing hermetically sealed containers, which are both easy to transport and display.

For further information please contact Ahlbrandt Systems UK Ltd at Unit 64, Edison Road, Rabans Lane, Aylesbury, Bucks. Tel: (0296) 432096.

Some of the Exhibits to see at Pakex

This year Pakex, the international packaging exhibition, is being held at the National Exhibition Centre, Birmingham from May 31st to June 5th. More than 15,000 sq m of space has been booked by exhibitors from around 25 countries. Quite probably if you attended the exhibition for the full time it was open it would be difficult to see everything. Our preview report is therefore merely designed to encourage you to go and see all the exhibits for yourself. Amongst the many press releases we have received from standholders we are publishing below a selection from those companies that claim to have new items to exhibit. Having said that, it can equally important to refresh your memory on what is available that is not totally new but could now solve a problem for you.

Alpha Dot Ltd will be displaying their latest Midjet ink-jet printer for the first time. This single line printer is simple to use and easy to maintain.

ITW Hi-Cone are launching the two-wide side-applied version of their Hi-Cone can carrier. It is being demonstrated as part of a complete can multi-packaging line. This Handi-Pac system applies the carriers to the side wall of the can, rather than the rim, and is designed to be used in conjunction with the Lock Top board.

Flo-Mech Packaging Machinery Ltd will have on display the Uva-Butler 1 Mechatronic/Ishida vertical form fill seal packaging system, the Avvolgipak 40/S semi automatic planetary bundle wrapper which use a narrow web of LLDPE stretch film, the SAD-16 fully automatic pallet wrapper from Strema and the Eco-Film 1i intelligent prestretch, a stretch-wrapper film prestretch system which, they claim, |thinks for itself' - all the user does is to decide on the prestretch ratio required and run the machine.

Stork Bepak BV will be displaying for the first time a new concept in robotic palletising and depalletising, combined with a new low pressure accumulation conveyor based on their successful eccentric roller design.

Metronic Systems Ltd are introducing two printing/coding machines. The Beta Jet provides a solution to bar-code printing in addition to 8 lines of text or logos, through their software. Their Lasertronic unit provides a method of printing codes via flexible fibre optics; such a system is suitable for marking problematic materials in virtually inaccessible areas.

Mondomix Holland BV will have on display for the first time their computer-aided process control and production monitoring system. Also on display for the first time will be their continuous and automatic density measurement with integrated feedback to a master control system. They tell us this is accurate irrespective of flowrate, temperature and pressure.

Holmes Mann & Co Ltd will be launching their new AP400 automatic palletiser. Together with the new AF46 automatic stretchwrapper, these units will be on display on Siat's stand and after the show at the Holmes Mann showroom in Bradford.

Technology Systems Ltd are to introduce their LightJet range of dot-matrix coding and marking system. LightJet is a moveable dot-matrix laser coder that incorporates a self-supporting beam delivery arm with three axes of adjustment, two linear and one rotary, to allow quick integration on production lines.

Signode, a division of ITW Ltd will be demonstrating their Saturn fully automatic pallet stretchwrapping machine. This unit incorporates their sensor stretch power prestretch system, which provides substantial film cost-savings. Such a unit is used for high volume random-sized loads.

Trigon Packaging Systems (UK) Ltd are introducing a range of Intact VSP films on their stand. These films offer advanced protection against dehydration, spoilage and abuse, they also extend shelf-line and enhance the presentation of foods.

Sauven Marking Machines Ltd are exhibiting a number of new machines. These include a small character ink-jet printer and two versions of their Codaprint film printer. The first Codaprint unit has been adapted to print recycling symbols on to webs of plastics film, whilst the second has been developed to print on to strapping material. This narrow print unit can add logos, messages or other information to plastics strapping.

Meyer Vi-Tech Ltd, as the European manufacturing and servicing arm of Meyer Machine Co of Texas, will be showing Examples of the Vi-Tech vibratory conveyors and Simplex bucket elevators. The new Series 300 bucket elevator will be there, alongside their Hydra-Flex hydraulic drive series and electro-mechanical drive Dyna-Flex units. The 300 Series has a single tubular frame that drastically reduces the number of dirt-collecting surfaces and ensures cleaner conveying and easier maintenance.

Turpins Packaging Systems Ltd will have a |sleeving clinic' as the central theme of their stand. A new square tub tamper-evident shrink sleeve applicator will be on display; with a mechanical sleeve opening function, it operates at speeds up to 60 a minute. Also new is their PLC-managed horizontal full body shrink sleeve applicator which operates at speeds up to 100 a minute working with PVC, PET, OPP or OPS materials.

M and P (Engineering) Ltd are giving pride of place to the 1992 version of their rotary piston filler. New design features include powered and preprogrammed head height and fill volume adjustments, quick release change-parts and the ability to accurately fill containers from 200 up to 2400ml capacity on the same machine. They are also offering to arrange a one-day visit by one of their service engineers, covering their Mather and Platt and M and P machinery anywhere in the UK at a special exhibition rate.

Hayssen Europa are introducing two developments. In the resealable technology sector, working closely with Supreme Plastics and Otto Nielsen, they have enabled St Ivel to launch the first resealable gas flushed cheese pack in the UK. Also on display will be their new 218ELD horizontal form fill seal machine with electronically coupled infeed and sealing die monitoring to allow the lap sealing of high barrier laminated materials.

Dutton Engineering (Woodside) Ltd has joined forces with Jaymech Food Machines Ltd to launch the JFM 750 cheese grating machine. Designed by Jaymech, it is being manufactured in co-operation with Dutton. This unit will handle up to 2 tonnes of cheese an hour and provide a shred of adjustable length and in various diameters.

D H Industries Ltd are introducing their new generation of NEM mini bottle unscramblers. This range of equipment, now made in Europe, features a unique hopper/elevator system which is so space-saving that in total the unit occupies up to 60 percent less floor area than some other systems, they claim.

Flexicon (Europe) Ltd are launching their all-plastics flexible conveyor/discharger. These modular units comprise a floor-mounted hopper and spiral discharge assembly, all constructed using FDA-approved polyethylene for simple access and thorough cleaning; the only non plastics contact part is the actual spiral which is available in stainless or carbon steel.

Double S Labels Ltd will be demonstrating a new thermal transfer print and apply system that will place labels around the corners of board packs. Part of their Combina range, it can be used as a stand-alone unit or as part of an integrated system.

Bradman-Lake Ltd will be showing new cartoning machines at NEC. Their SL80HF combines a semi automatic load system with an in-line hot foil coder. By printing flat, before the cartons are erected, loaded and closed in one pass, it eliminates off-line working. The SL90 brings fully automatic cartoning to packers requiring speeds up 90 cartons a minute. Their FCC Triliner has been up-rated to enable front and side flaps of top-load cartons to be closed and sealed in-line at speeds up to 250 cartons a minute.

Medway Packaging Systems have been appointed UK sole distributors for the packaging machinery made by SMI of Italy. An SMI system will be seen for the first time in the UK. Their multi-packers can operate at speeds up to 300 packs a minute and their shrinkwrappers at up to 70 packs a minute with film registered to the packs, cans or bottles either unsupported or on trays or flat pads. Whilst they are to cease representing Kisters in the UK, Medway are well underway developing their own high speed packaging machines but details are not available yet.

Graseby Goring Kerr will be showing three new models. These include an innovative metal detector that is claimed to introduce new and greater sensitivity to metal detection. They will also have on their stand a checkweigher designed to process heavy packs up to 60kg, and a new design of metal detector that features open construction to meet health and safety requirements and provide ease of cleaning.

Corporate Packaging aim to launch five new machines at Pakex. The bulk of this new machinery is made in France and includes both in-line and rotary volumetric bottle fillers and a system designed to wrap multi-packs of cups into two layers at speeds up to 150 packs a minute. They will also have on display a Hittpac AKH-051 flexible cup filler that can handle multi-packs of four cups joined together, in addition to single cups in paper or plastics. Other machines seen for the first time will include a fully automatic stainless steel packer for multi-packs of brick-style cartons and a tray packing system that forms trays from plastics sheet.

Cermex UK Ltd will be showing the latest addition to their range, the case/tray packing robot ER.30. It will be seen collating and packing cartons of liquid into cases. Videos will also demonstrate its capability in other areas, like collating and packing flowraps, small bottles and blister packs. They tell us this unit is already providing that it can cope with products that conventional machines can't handle, by packing the products row by row rather than forming the complete collation first. They will also be showing a mini wraparound case packer, a mini palletiser, a fully automatic robotic palletiser, a high speed case packer and a compact side-loading case packer.

PPM Albro, part of GEI (FCL) Ltd is introducing a small footprint Omega powder filler. This new B-base filler has been developed following the success of their larger C-base version. It is suitable for a wide range of free and non free-flowing powders and will operate at speeds up to 350 containers a minute.

Purdy Gravfil, part of GEI (FCL) Ltd, are launching their Premier liquid filling machine at the Show and they will also demonstrate their Miniflo system. The Premier system offers programmable product changeover, a quick-strip facility and clean-in-place system.

Masterfil Ltd are introducing three machines at the exhibition. A machine for filling and acid-based products will be demonstrated for the first time, along with a new bench-top mounting semi automatic filler. A new high-tech in-line filler will also be there. The D1250-AS will deal with highly corrosive products; it uses a titanium cylinder with PTFE seals and acid-resisting hoses. Their bench-mounting horizontal unit will fill volumes from 5 to 1000ml. In addition visitors will also be able to see the weigh-filler for the first time on a stand.

CMB Engineering Group Plc are launching a high speed, neck-guided air conveyor for plastics bottles. This unit, from Simplimatic Engineering, features an inverted V-shaped channel from which the bottles are suspended by their neck rings and blown along at speeds of more than 1000 a minute. The new Simplimatic modular conveyor will also be seen for the first time. Constructed from standardized stainless steel and plastics components, the Simpli-Kleen reduces assembly time and costs.

Cintex Ltd is introducing a new checkweigher and metal detector. The CS3000 checkweigher offers a high level of accuracy. Designed for use in wet or greasy environments, this unit features an LCD screen that can be used in graphics mode for setting-up, etc, and its weight range capability is 3, 5 or 10kg. Their wireless remote control metal detection system, believed to be the world's first, will also be on the stand. This is very significantly upgraded unit from the AutoSearch. It features infra red remote control and offers central line detection.

Limpet Tapes Ltd are combining with Siat of Italy to demonstrate a wide range of end-of-line equipment. They are launching a new palletiser and their new AF3/E pallet stretchwrapper will also be on show. It features built-in electronics to provide for add-on facilities as customer's needs grow.

CMB Carton Systems will be demonstrating how a robot can be used on a pack- filing line between their own carton erecting and carton closing equipment. Such a system speeds up the whole operation and ensures complete accuracy. This development follows an agreement made with Adept Technology Inc, the US robotics company. Their PackOne robot has been specifically designed for use in the food industry.

United Closures and Plastics Plc will be showing-off an eye-catching promotional ROPP closure which demonstrates the potential of the new side-decorating equipment they have recently installed. The Scottish promotional cap will be available on the stand to demonstrate the style of graphics that can be achieved.

Alpma GB Ltd will have on their stand for the first time the SAN 60, which has been developed from the traditional horizontal wrapping machines for soft cheese. Made entirely in stainless steel and food grade plastics, this new unit can be equipped with a CIP system for product contact areas. Developments in basic mechanical functions allow higher speeds to be achieved, whilst also reducing wear, they tell us.

Engelmann and Buckham Machinery Ltd will be demonstrating a new filling and sealing machine from Hamba of Germany. Equipped with microprocessor control, it can handle from two to twelve double lines and achieves outputs up to 57,600 cups an hour. German manufacturers Hassia have designed the THL 15/22 thermoform/fill/seal machine for high performance. It has a capacity of some 27,000 cups an hour. Klockner Bartelt will be demonstrating the RPM 100 intermittent motion pouch packer and Cloud RCM high speed continuous motion pouch packer. Peelable foil lids that are sealed directly to plastics containers is part of a system from the Swiss Rychiger company that will be seen. Serac's latest screw capper for high outputs will also be seen on their stand. The newly introduced UniMove vacuum lifting system will be featured; this is the equipment that will lift loads up to 600kg.

Lawson Mardon Group will feature innovation as their main theme. On display will be a series of newly designed tamper-evident plastics closures from Lawson Mardon Plastics. Known as TE closures, these are moulded in high density polyethylene and the system is based on a distinctive security band, which is an integral part of the closure. LMG Fibrenyle have now developed techniques to allow the extrusion blow-moulding of PET containers. Such a system offers greater flexibility to create new shapes and designs.

Linx Printing Technologies Ltd will be demonstrating a number of new developments in coding capability, ink formulation and computer control. Linxnet, their new system for centralised multiple printer control, will be on show. This allows up to 30 printers to be controlled from a central computer.
COPYRIGHT 1992 Food Trade Press Ltd.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1992 Gale, Cengage Learning. All rights reserved.

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Title Annotation:sealing technique used in food processing industry
Publication:Food Trade Review
Date:Apr 1, 1992
Words:3248
Previous Article:Keeping labelling information secure.
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