With supermarkets now demanding far more than Heinz’s 57 varieties of soup, flexible manufacture is a key issue in the food handling and processing industry. The bigger variety of food products and rapid changes in demand have led manufacturers to develop novel approaches to materials handling. These may have lessons for other industries shifting from large-volume, single-product lines to multi- and variable batch production.
Food producers are looking for machines that can handle dozens of products and many jobs, rather than one product faster. Manual packaging operations are being replaced with high-speed product handling systems and automatic carton erectors and closing machinery.
However, the food sector can still be difficult for automation suppliers and robotics companies to break into, because manual workers remain cheaper.
Until the late 1980s, food packaging operations were labour intensive, with automation limited to the process side and primary packaging. Changing from one product to another was time consuming and complicated, while on-site warehouses held large stocks of products and packaging. Manufacturers followed rigid planned maintenance programmes, with management information limited to occasional reports about individual machines.
All that has changed in the past decade, according to Bryan Wheeler, managing director of CKF Systems, a Gloucestershire-based manufacturer and project manager of materials handling systems.
‘Food manufacturing has been radically revamped, though most of the systems are still customised to meet the individual requirements of different product lines,’ he says. ‘The new approach has been driven by the need to improve operating efficiencies, handle increased volumes and have the flexibility to accommodate new products.’
Martin Keay, technical manager for the Processing and Packaging Machinery Association, says the drive for food process and automation is coming from the demand by supermarkets for more products and variety. ‘This calls for rapid product or pack size changes on the same machine, with fast cleaning capability a high priority,’ he says.
On the IT side, most new food process installations are supported by integrated management information systems, which generate production and operational reports.
There have also been advances in the use of servo-motor controller-linked systems and centralised PC-based control. Just-in-time stock delivery is vital in the food industry, says Wheeler, with constant demand for fresher products.
The need to monitor hygiene and judge cooking means the human touch is still a vital element in many operations. However, automatic vision and quality inspection systems are being development by UK companies such as Safeline and Loma, which have introduced advanced metal detection systems.
Vision systems, colour inspection and X-ray systems also play an increasing role in hygiene checking. Vision systems now being developed will allow robots to pick up fragile, randomly oriented products on a line and pack them into boxes.
Wheeler says CKF has supplied and project managed integrated materials handling systems for food giants such as Nestle, Cadbury Schweppes and Unilever. He believes that for big players such as these, the next step will be to develop ‘interconnected packing and process plants, with operation systems which will allow a small number of multi-disciplined technicians to monitor, control and maintain the complete operation from a central location’.
Enhanced control will enable technicians to download new recipes and perform size changes without leaving the control room, while intelligent robots will perform a wider range of tasks. Management information systems will provide operational details and diagnostics for preventive maintenance.
Wheeler has already seen great changes in automation. ‘Food lines which typically involved 20 to 30 operators are now down to four or five. Popular canned-drink lines can handle 4,000 products a minute or more, and Swiss SIG and US Schubert robots are being introduced at companies like Cadbury’s, Findus and Nestle.’
Switching to servo control
Many materials handling equipment suppliers have replaced mechanically driven systems with servo-control technology. Wheeler predicts: ‘Purpose-designed PC-based control software will soon become commonplace for on-line control and management information.’
CKF has introduced more flexible servo-control and handling technology for food, pharmaceuticals and even an auto-component conveyor line. Pharmaceutical companies have a great demand for flexible packaging and high-speed product lines, integrated with plant management systems or complex control functions. They have similar demands to the food industry for just-in-time delivery, stock control and hygiene.
In both the food and pharmaceutical industries, hygiene demands in-place cleaning equipment and flexible filling systems, with greater emphasis on servo technology to handle quicker product size changes.
The PPMA’s Keay says: ‘This is not simply a matter of putting a servo drive on every control or adjustment knob. It means fundamentally changing the way a machine works.’
Some of the most advanced UK-made servo-drive machines include flow-wrapping machines from Rose Foregrove and GEI Autowrappers. Rose Foregrove developed its first seal machine, Flowpak, in 1957, and in the 1980s introduced electronic multi-axis flow-wrap machines, where each machine was run independently under microprocessor control.
The company’s latest system offers PC-based controls for servo-driven Flowpak machines, where the machine in-feed, wrapping-material feed and end-sealing jaw unit are driven by PC controls using a Windows-style interface.
Paul Field, Rose Foregrove’s International sales manager, says: ‘PC control is a key direction in the food industry because it offers flexibility and simple operation, and can help integrate several machines into complete lines, for integration with management information systems.’
As far as robots are concerned, Keay adds: ‘They are still considered expensive for most handling operations in the food industry, compared to others. Packaging speeds are also high compared with component assembly tasks in the automotive and electronic sectors.
‘At the end of the line, there is the problem of handling very heavy boxes, and orientating and picking up variably shaped and easily damaged products.’
Food handling robots such as the US’s Schubert, Switzerland’s SIG system and French Cermex system are beginning to gain ground in UK food packaging lines, though Tim Robinson of Field Packaging Systems says: ‘Robotic systems for food packaging are still few and far between in the UK, because the initial cost has to be justified by high volumes.’
Field has supplied packaging systems equipped with Schubert robots for Cadbury chocolates and Birds Eye frozen products, using four-axis robots equipped with grippers or vacuum cups which can locate, orientate and pick up products at speed.
French-built Cermex end-of-line packaging machines can handle high-speed flow-wrapped products, which arrive along a food line at 700 units a minute. The items are then packed in cartons, cases or multi-strip plastic trays by a robot packer which can produce up to 60 cases a minute.
Dick South, managing director of Cermex UK, says: ‘The issue is not speed of packing, but how fast the customer can make the product. Large food companies also face the challenge of wanting to buy machines to handle products they can’t even imagine five years from now. Contract packers rarely buy sophisticated end-of-line packers because of the rapidly changing demand for products.’
With more than 3,000 end-of-line packaging machines operating in a wide range of industrial sectors, Cermex sees rising demand for more flexible conventional or robotic packing machinery.
South says: ‘Invariably, different products and packaging styles from food to detergents, and light bulbs to shampoo require systems which are tailored to each specific installation. Companies like Unilever now call for long-term flexibility because robots have to handle frequent size and product changes, without the aid of special handling tools.’