Checkweighing

It is undeniable that checkweighing and metal detection equipment are essential for all food manufacturing facilities. Accurate weighing is an absolute necessity - obviously the manufacturer wants to manufacture a standardised item, both to ensure consumer confidence and reduce ingredients wastage. On the other hand, there is a legal impetus behind metal detection, and any occurrence of metal traces in products will result in adverse publicity that can affect future sales. The purpose of this article is to merely outline some recent developments, some of which are demonstrated via case studies.

Aja, UK

Aja of Twickenham, Middlesex has launched two new semi-automatic multihead weighing systems. These have been specifically designed to replace expensive manual portion and assembly weighing of difficult, light, sticky, wet ingredients and raw material for supermarket packs. Based on established multihead combination weighing technology, the Aja Fasco AWS and BWS Multiweighs incorporate unique handling and transfer systems, thereby eliminating sticking, bridging and 'hanging up' of products. The AWS and BWS Multiweighs facilitate multihead weighing automation, whereas this was impossible with traditional gravity-driven rotary and linear multihead scales. The systems feature a compact design, enhanced portability and facilitate easy cleaning, thereby providing further benefits for companies striving to reduce labour, guarantee accuracy and reduce waste.

The principle of the BWS Multiweigh comprises a series of small, self-cleaning conveyor belts. Raw materials and ingredients are conveyed to the weighhoppers where they are weighed in combination, thereafter being transferred to the finished pack via a further belt conveying system. This ensures that every part of the portion reaches the finished pack, bag, pot or tray. Raw material residues must not be left during the weighing process. The BWS Multiweigh is particularly ideal for handling very light, delicate and stringy ingredients and products.

The Aja AWS unique Archimedes screw-feeder system controls the raw material feed to the weigh-hoppers. It incorporates a shutter, scrap and clean system, designed to eliminate material loss within the system. This is a truly remarkable weigher, capable of handling the most difficult, sticky and wet ingredients. It is particularly suitable for weighing ready-meal components, salad pot portions, sticky chops and diced meat, fish and poultry.

Fortress Technology Europe, UK

Located in Banbury, Oxfordshire, Fortress Technology specialises in developing metal contamination solutions. It collaborates closely with its customers' engineering, quality assurance and production personnel. Company engineers have developed innovations to improve detection levels, reduce product waste and lower ownership costs.

The Phantom range of metal detectors utilises the Auto Test electronic testing system. This system has been developed to complement or replace manual test procedures, providing myriad cost and performance benefits. As it is devoid of operator intervention, the system tests its functionality at regular time intervals, regardless of frequency or physical location. Automatic testing also resolves the problem of inserting the test sample into the product. This is a particular issue when such continuous flow products as grains, powders, liquids and sauces are being tested. As the Fortress Auto Test feature is fully electronic, with no requirement for additional services or component parts, these metal detectors can be used throughout the production process. The earliest range of Phantom metal detectors were launched a decade ago, yet even the new generation remains simple to use and maintain. Fortress Technology carries a comprehensive range of spare parts and will undertake upgrades.

Ishida Europe, UK

The Birmingham-based Ishida Europe has incorporated advanced product recognition technology within its latest checkweigher range. The DACS-W series can incorporate a camera that enables pack images to be stored in the checkweigher to ensure immediate recognition. This enables product set-up and changeovers to be undertaken in seconds, without any requirement for additional operator intervention.

The camera is integrated with the PLC control on the DACS-W. This provides an online help-screen, together with self-diagnosis and fault-finding functionalities. Furthermore, improved networking integration facilitates centralised control, providing information to ensure efficient management of operations across single or multiple sites.

The Ishida unique Digital Signal Processing (DSP) chip facilitates accurate processing under a wide range of weighing conditions, whilst the Ishida-built load cell achieves high sensitivity, response and accuracy. When combined with a lightweight conveyor, enhanced direct-drive motor and a special low-friction belt, Ishida claims these features serve to make the DACS-W the fastest and most accurate checkweigher in its class. For example, the DACS-W-012 can handle products weighing between 10g and 1.2kg at a maximum output of 270PPM.

A wide range of belt and conveyor sizes is available to suit the size of individual products, together with optimising pack handling and product throughput. Its robust construction, featuring smooth contours and quick-release conveyors, facilitates fast, easy cleaning.

Lock Inspection Systems, UK

Headquartered in Oldham, Lancashire, Lock Inspection Systems has supplied checkweighing and metal detection equipment to companies in the food, pharmaceutical and packaging industries for over 50 years. During Interpack 2008, Lock showcased its recently-launched MET 30+ Universal range of metal detectors, comprising the 3f, hf and 3f/hf models and a leading pharmaceutical metal detector.

Incorporating the latest technology, the MET 30+ hf achieves up to 30 per cent greater sensitivity than its predecessor. It incorporates a single high-frequency, crystal-controlled oscillator, being primarily designed for snack foods and bakery applications. The MET 30+ hf is used to inspect such dry foods as biscuits or crisps at 875Khz, which is three times greater than standard food industry detectors.

The Lock MET 30+ Universal 3f is the world's first fully-automatic triple frequency detector, capable of undertaking highly accurate inspection of both polyfilm and metallised packaged products. The 3f operates at three crystal-controlled frequencies - high, medium and low. It incorporates an integral automatic frequency selection facility, regardless of the product or packaging. When inspecting poly-wrapped products, the detector will automatically select high-frequency, whereas it will operate at low frequency for a product packaged in metallised film. The PLC for the MET 30+ 3f can retain settings for up to 100 products.

Loma Systems, UK

Loma Systems of Farnborough, Hampshire has launched the compact, versatile CW3 checkweigher for food applications. This can be easily integrated into high-speed lines, achieving belt speeds of 120m/min. Fast and accurate, the CW3 can deal with a wide range of flexible and rigid packs weighing up to 1.5kg. Future models will be able to handle packs weighing more than this.

Such elements as cleanliness and enhanced durability have determined the machinery design, thereby complying with the company's 'Designed to Survive' ethos. The machine operates accurately at low temperatures, being resilient to environments bordering on freezing. Entirely constructed from stainless steel, the CW3 Checkweigher will withstand cleaning processes involving industrial methods and chemicals. It is designed to satisfy the toughest industrial environments, satisfying IP69K 'harsh environment' cleaning specifications and withstanding high-temperature, high-pressure washdown regimes.

Mettler-Toledo, UK

Leicester-headquartered Mettler Toledo Safeline manufactures metal detection systems for many complex and demanding applications, including fresh, frozen, wet, packaged, bulk, sticky and fragile products. Its engineers frequently design and realise bespoke systems for clients. The machines feature a robust, hygienic, welded fame designed to satisfy the rubrics of industry standards, retailer codes and to ensure GMP and HACCP compliance. The open frame design of the metal detection systems serve to eliminate ledges, crevices, dirt traps and horizontal surfaces, facilitating easy cleaning. Fully mobile Mettler Toledo Safeline systems can be mounted on large, easy-to-move castors.

Systems can be designed to incorporate any Mettler Toledo Safeline R series detector head. The 'R' series Signature features a membrane key panel with an easily-operated menu-driven operator interface. However, the 'R' series Profile system applies colour 'touch-screen' technology featuring an intuitive windows-style icon-driven interface. Its metal detectors have a rectangular aperture and are extremely sensitive to all metal contaminants. These detectors provide fully-automated product inspection when integrated with materials handling and conveyor systems. The 'R' Series rectangular heads are designed for use on a wide range of standard or bespoke conveyor applications, including those handling loose raw materials, processed products, or packed, finished items. Mettler-Toledo also manufactures metal detection apparatus specifically designed for use with conveyor systems; vertical form, fill and seal machines; pipelines for pumped liquids and slurries and gravity fall systems.

Furthermore, Mettler Toledo manufactures a range of dynamic checkweighers, designed for integration into production lines for weighing products in motion.

The standard design includes a height adjustment device, reversible transport direction and continuous belt speed control. It is possible to use Mettler Toledo Garvens S3 models to weigh products up to 6kg at a maximum throughput of 400 products per minute (PPM).

S+S Inspection, UK

The German subsidiary of S+S Inspection, whose UK base is located in Fareham, Hampshire, has recently installed a metal detection system to the Aldenhoven prepacked meat and sausage company in Gelsenkirchen, Germany. The company specified that it wanted to exceed International Food Standard requirements. In particular, Aldenhoven needed to find any trace of small metal particles in the sausage meat filling that could emanate from the production process. This strong, variable product, combined with high inspection levels and wet operating conditions necessitated the application of the Liquiscan metal detection system, incorporating a Genius control unit.

Designed for pumped liquid and paste product applications, the S+S Liquiscan can be integrated with all types of conventional filling machine types. The Genius PLC ensures that the quality of automatic processes is maintained. This incorporates Auto-Learn software, which automatically factors product effect changes into the processing parameters. The datalogger can record 1000 events and produce date/time-stamped documentation complying with HACCP and ISO 9000 standards. As an additional safeguard, Aldenhoven also installed a S+S Unicon-D end-of-line metal detection system to identify magnetic and non-magnetic contamination in packed sausages and meats immediately before despatch.

Smith's Detection, USA

Smith's Detection in Alcoa, Tennessee, is one of the world's leading manufacturers of X-ray inspection equipment, having installed over 40,000 systems during the past 40 years. All machines apply the latest X-ray technology to detect and reject harmful physical contaminants and other defects in packaged products, whilst simultaneously checkweighing each product. The X-ray inspection equipment from Smith's replaces traditional metal detectors and checkweighers with an integrated unit that conforms to HACCP hygiene standards. In addition to detecting metal contaminants, the X-ray systems can also detect glass, stone and calcified bone using SimulTask 4.0 proprietary image analysis software.

X-ray inspection technology utilises product absorption principles for both contaminant detection and weight evaluation. In the same way that contaminants are detected with energy absorption levels, product weight can be determined according to the absorption levels of the diode receptors located beneath the product. As opposed to traditional checkweighers that evaluate products according to 'scale weight,' X-rays can be calibrated to evaluate compartmentalised products for individual weight zones (ideal for frozen entreés) in addition to total product weight. The systems are unaffected by freeze-thaw production environments.

Thermo Fisher Scientific, UK

Thermo Fisher Scientific, located in Rugby, has recently launched its Apex 100 entry-level metal detector. This is designed to ensure food safety and brand protection, require minimal initial investment. Contaminant detection is an integral element of the food production process, and the Apex 100 ensures that all metal types are detected in food products prior to shipping. It also helps customers quickly and completely achieve quality objectives, protecting expensive downstream production equipment.

Key features and benefits of the Apex 100 include:

• quick installation: integrated electronics with no external boxes to mount or wire
• fast personnel training: easy-to-use icon-driven interface
• durability: the stainless steel and ABS plastic design are resistant to food factory applications and IP65 washdown
• easy integration: a built-in Quality Assurance Test (QAT) enables customers to easily validate performance
• application flexibility: dual frequency and gain capability
• sanitary design: the blue, epoxy-lined aperture is easy to clean and does not hide dirt or contamination.

Concluding remarks

It is now obligatory for all food and beverage manufacturers to undertake metal detection at some point during the production process. The latest generation of detection equipment is more sensitive than before and can handle products emanating from modern, high-speed lines. On the other hand, checkweighing has increased in importance for financial reasons, as manufacturers want to avoid ingredients wastage. The latest checkweighers are supremely accurate, easy to use and capable of sampling on a more regular basis than was hitherto possible.

For more information, go to www.aja-uk.com; www.fortresstechnology.com; www.ishidaeurope.com; www.lockinspection.co.uk; www.loma.com; www.mt.com/pi; www.sesotec.co.uk; www.smithsdetectionpid.com and www.thermo.com/apex.

Please note that many product names are trade marks or registered trade marks and should be treated as such.

Thermo Fisher Scientific's Apex 100 ensures that all types of metals are detected in food products prior to shipping No metals permitted The Smith's Detection Eagle X-ray product line inspects packaged items for defects, missing items, foreign objects, size, shape, count and weight An eagle eye Aldenhoven installed S+S Inspection Systems' metal detection apparatus to find all miniscule traces of metal particles in sausage meat filling Checking the sausages Mettler Toledo's Garvens S3 checkweighers can weigh products of up to 6kg at a maximum throughput of 400PPM A versatile checkweigher Loma Systems' compact, versatile CW3 Checkweigher can be easily integrated into high-speed lines, achieving belt speeds of 120m/min Weighing at high speed The Lock Inspection Systems' MET 30+ hf achieves up to 30 per cent greater sensitivity than its predecessor Highly sensitive apparatus The Ishida DACS-W checkweigher series can incorporate a camera that enables pack images to be stored for immediate recognition Cameras to the fore The Phantom range of metal detectors from Fortress Technology Europe utilises the Auto Test electronic testing system A phantom from the fortress