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A marriage of convenience

The disciplines of checkweighing and metal detection, for so long independent of one another, are now being combined, freeing up vital space for other production and packaging activities. Rod Abbott reports

Although many metal detection systems remain standalone, in that they offer metal detection only, quite a number are also being integrated with checkweighers to provide a combined system of weight and metal inspection. For these combined applications it is possible to set up communications between the two units so that, when the product details are changed on the checkweigher, the details are automatically called up on the metal detector.

Unlike the checkweigher, the metal detector still requires a degree of operator set-up on such changeovers. This is due to the fact that the products being inspected may change their characteristics and, as a result, may lead to a change in the capability of the machine to accurately detect metal.

Packaging materials, product densities and characteristics all have a major impact on the ability of any inspection device to detect a contaminant. With a metal detector this is particularly true with what are called “wet” (conductive) products. To the producer this change may not be evident, but to any modern day metal detector these changes can be significant.

Inaccurate settings on the detector can result in an unacceptable level of false rejects or poor levels of sensitivity/contaminant detection. When false rejects become excessive, it is not unusual for the user to make the detector less sensitive or in extreme conditions simply switch it off. So it is vital that the detector is able to adjust/learn these changes quickly and effectively, an objective that the Fortress checkweigher and metal detector combination has accomplished.

The facility to save and recall multiple products within the Fortress Phantom has been developed to keep the system simple, yet reliable in operation. Recognising that there is often little to differentiate inspection systems in today’s market, Fortress continues to focus on ease of use for operating and maintenance staff. The calibration (phase adjustment/learn) on the Fortress allows the detector to immediately learn and store the characteristics of each of the individual products. Often, it just takes an individual pack to achieve this, minimising the interruption to production.

Generally, the operator initiates this function by a single key press, but for some products, which can change over a production run, it can be automatic. Where automatic calibration is chosen limit controls ensure that contaminated product cannot be learnt and ignored. Fortress also works towards providing systems that are self-checking and that provide early warning of potential problems.

The Phantom model includes a number of failsafe features to ensure that any automatic reject device is checked for accurate and reliable operation. Immediate alarms are generated in order to warn the operator if product fails to enter the reject bin or if there is the potential of failure through insufficient air to operate the pneumatic reject. Regular testing of the machine can be scheduled by a timed quality alarm, which will prompt the operator to pass test packs. Results of quality testing and fault logs can all be captured, time-stamped and reported using a data capture system that can be linked into the factory’s existing computer network.

Mettler Toledo’s compact Garvens S3 CombiChecker combines a checkweigher and a metal detector in one unit, which is said to enable central article data editing at the weighing terminal of the checkweigher, quick and easy article changeover and rejection of off-weight and metal-contaminated products. It can store up to 200 product settings and classify items in three weight zones. The Safeline metal detector contained in the unit features zero metal-free zone technology. This enables mechanical integration with the checkweigher’s infeed conveyor and has optimum detection sensitivity for many different products.

As the products pass through the CombiChecker, product weights are measured and two pneumatic pushers or other rejecting devices separately reject metal-contaminated products. The terminal of the checkweigher displays weights, counter levels of the weight zones and of metal detection, and provides statistical information about production. Designed for integration into production lines for weighing products in motion, its hygienic design facilitates cleaning and meets the stipulations for food processing industries.

The Garvens S3 Shark model is designed for product weights of up to 6,000g at a throughput of up to 400pieces/min. Water build-up/contamination is minimised via the elimination of level surfaces on the conveyor and weigh cell supports. Round tubes are used on the horizontal sections of the frame, and minimal contact conveyor support clamps and open frame construction facilitate cleaning.

Seam welding is used to improve hygiene and reduce the risk of bacteria build-up, while the reduced number of support legs, self-draining framework, hygienically designed cable runs and additional ‘customer cable’ duct combine to provide a flexible system specifically tailored to users’ requirements.

In addition to standard production models, customised solutions are available for a range of processing environments, with models achieving HACCP accreditation. The standard design includes a height adjustment device, reversible direction of transport and continuous belt speed control, while the modular concept of the S3 allows for ease of servicing and ensures that it can easily be extended via further options.

Easiweigh, part of the GSH Group, has developed a metal detector checkweigher that eliminates the need for two separate processes, significantly saving on floor space and requiring lower plant investment. The unit provides accurate weight control and ensures that the product is free from any metal particles/goods in one integrated operation. The checkweigher capability ensures that products exactly match the specified weights required on the production line for guaranteed accuracy and to prevent discrepancies. The system operates at linear speeds of up to 100 metres/min and can achieve ± 0.3g accuracy levels.

The machine has been designed to handle obscure shapes and sizes and to be suitable for high humidity environments including the fresh and frozen food sectors. Additional features include the ability to operate at particularly high or low speeds, all controllable from the keyboard, with a self-calibration device and removable conveyors. The system also benefits from a graphical display panel for ease of operation where data can be managed and printed and speeds adjusted. The software can store up to 100 product programmes for simple recovery when required.

Constructed of stainless steel, Easiweigh says the robust design allows for low maintenance, while removable conveyors aid cleaning. Optional accessories include ejection systems, infeed and outfeed conveyors, a wind-prevention tunnel, feedback function and 24-panel column printer.

The latest addition to the Easiweigh range is a compact high-speed, twin-lane optical counting system, which can be used as either an optical counting machine or a weighing system.

The new system is said to offer an ideal, cost-effective solution for small packaging companies or start-up businesses with smaller packing requirements. Constructed in stainless steel, it is designed for counting or weighing fresh or frozen produce at speeds of up to 30 packs/min and handles a range of product shapes and sizes.

Advanced Dynamics’ Tesab TC 3 checkweigher is an automatic, stainless steel machine with Windows XP-based management software. The Tesab TC 3 has been developed for the food sector, including those dealing with meat and poultry, dairy, and fresh produce. Capable of handling pack weights between 10g and 40kg, at speeds of up to 75 packs/min, it features an easy clean design, multi-lane use with touch-screen control, feedback and data management in percentage terms and online networking capabilities. Options include a combination metal detector, easily removable conveyors, a printer for data management and a scanner for multi-product batches and alternative rejects.

Advanced product recognition technology is one of several new features on the latest checkweigher from Ishida Europe. The DACS-W series can be specified with a camera that allows pack images to be stored in the checkweigher for immediate recognition, enabling product set-up and changeovers to be carried out “in seconds” without additional operator intervention.

The camera forms part of a powerful, intuitive new graphic interface on the DACS-W that simplifies operation and speeds up training. The swivel-mounted colour touch-screen provides easy to follow instructions for line operators with online help, self-diagnostics and fault finding. In addition, improved networking capabilities allow centralised control and provide detailed information to ensure efficient management of operations across single or multiple sites.

Ishida’s digital signal processing chip permits accurate signal processing under a range of weighing conditions, while the load cell is said to achieve high sensitivity, response and accuracy. Combined with a lightweight conveyor, enhanced direct drive motor and a low friction belt, the DACS-W-012 can handle products from 10g-1.2 kg at up to 270 packs/min.

A range of belt and conveyor sizes is available to suit the size of individual products in order to optimise pack handling and product throughput. A robust construction, with smooth contours and quick release conveyors, permits fast and easy cleaning. Options include a fully integrated, high-performance metal detector.

Of course, X-ray technology offers advantages over standard metal detectors, as it enables the detection of other foreign materials as well as metal. It distinguishes between “legitimate” metal, such as clips on the ends of sausages or aluminium tins, while still monitoring and identifying unwanted items.

It can therefore be a valuable tool in helping manufacturers and retailers avoid the major implications of product recalls owing to contaminants. In addition to the costs involved in removing product from the shelves and the corresponding loss of sales, recalls can also lead to a drop in consumer confidence and potentially expensive litigation. “Today, with heightened awareness of food safety among consumers, manufacturers want maximum peace of mind, knowing that the products that leave their factories are totally safe,” comments Ishida Europe marketing director Paul Griffin.

Ishida recently launched its IX-GA range of X-ray machines. This is intended for detecting foreign bodies including aluminium, tin, glass, stones, hard rubber, plastic, bones and shells in a variety of packed and unpacked fresh food products including meat, poultry, fish and ready meals, as well as dry and frozen foods.

The IX-GA range uses a self-learning genetic algorithm technology to offer maximum detection sensitivity and reliability. The machine can detect impurities down to 0.3mm in size and can also spot missing items or damaged products. In addition, the place of contamination can be accurately pinpointed. It can handle top sealed and thermoformed trays and flexible bags as well as unpacked product. It features a Windows XP operating system, while an advanced auto-set function enables the X-ray output and sensitivity level to be automatically set up for each product.

The machine’s conveyors and belts are manufactured to IP66 and the main body to IP65 regulations, and it conforms to HACCP standards. Its hygienic design, with easy, tool-free access to all parts, allows fast cleaning. A stainless steel body and three sets of lead curtains provide protection for operators. Other safety features include warning lamps when the machine is in operation and automatic stopping of the X-ray process if the inspection cover door is opened or if a product remains in the inspection area.

Meanwhile Loma has produced an X-weigh system that enables the X-ray system to weigh the product while simultaneously inspecting for foreign body contaminants in one compact format. The X-weigh is said to be unaffected by pack rate, speed, vibration, air turbulence, pack orientation or stability. It supports a comprehensive reports package showing trends, give-away and batch analysis. Ethernet can network the statistical information that the software provides to a central plant computer or SCADA system. The X-weigh allows for multi-lane checkweighing, which means a number of lines can be run through the system with each pack inspected according to its own target weight parameters.

X-weigh also offers combined weighing and object checking, ensuring that packs with more than one weight zone are compliant for both overall pack weight and individual weight zones. This makes it suitable for inspecting consumer-ready products such as packs of ready meals and snack products.

Contact details

Advanced Dynamics
T: +44 (0)1274 22030;

GSH Group
T: +44 (0)1733 202088;

Fortress Technology (Europe)
T: +44(0)1295 256266

Ishida Europe
T: +44 (0)121 6077700

T: +44 (0)1252 893300

T: +44 (0)116 2357070

Loma’s X-weigh system weighs product while simultaneously inspecting for foreign body contaminants Ishida recently launched its IX-GA range of X-ray machines Options available for Ishida’s DACS-W series checkweigher include a fully integrated, high performance metal detector Mettler Toledo’s Garvens S3 CombiChecker combined metal detector and checkweigher unites the advantages of in-line weight monitoring and metal detection in a compact system Advanced Dynamics’ Tesab TC 3 checkweigher has been developed for the food sector Fortress checkweigher and Phantom metal detector combination – Fortress continues to focus on ease of use for operating and maintenance staff