By automating plant or the production of consumer goods it is possible to improve the efficiency with which products are processed or packed ready for transport to the user.
This is not as simple as it sounds. There are many options available to automate basic tasks and position them for the next stage of the process. Add the need for quality control and removing items that do not meet specifications and it becomes more difficult to find the right handling system.
Everyone is familiar with moving conveyors on which items are carried on an (often rubber) belt - you see them at supermarkets and most of us have spent more time watching airport baggage carousels than we would have liked.
There are many types of conveyors in addition to the moving rubber belts we all know. Conveyor systems can also be built using motorised rollers, vibrating beds or even rotating balls (ball transfer units), which can switch the direction of products or pallets and deal with heavy items in multiple units.
The system is used to move anything from pallets to raw materials of all shapes and sizes. For example News International, publisher of newspapers including The Times and The Sun, now uses an automated handling system installed byFKI Logistex
. It is claimed to have increased pallet throughput by half and cut staff costs considerably. The News International system has 12 automatic palletisers and stretch wrappers fed direct from the presses, with conveyors moving pallets of papers to a series of delivery bays where vans collect papers for distribution.
It uses a conveyor about a mile long with an external loop (a bypass conveyor) that can be employed to even out the flow of pallets to the vans through secondary or tertiary routes (if required) and ensure the presses are always working at full capacity. This system is run from a production management system, which optimises the routes of pallets to the waiting vans.
Programmable logic controllers (PLCs) connected via DeviceNet to a control PC use optical 'eyes' to sense back-ups and send a signal to route pallets via another path if a back-up or jam is detected.
The operation is capable of getting 68 bundles of newspapers a minute through from presses and, as it does not rely on manual loading of pallets, staff costs have been reduced.
Another big advantage of this conveyor system is that on slow periods one palletiser can be shut down for maintenance purposes so that all the palleting is covered by the other units and the newpapers routed to cover the missing machine.
The pattern of cost savings from greater automation of handling processes is replicated in other installations and the benefits can be significant.
For example,Welconstruct Customer Solutions
has installed a conveyor-based palletising system for a carton-packaging manufacturer that cost about £600,000. The company expects the system to pay back in two to three years. Like the News International system, this is fully computer controlled and requires about half the number of staff used in the old manual palletising system.
There are other options, however. Monorails and tracks are able to transport large items efficiently and cost-effectively. For instanceHeatrae Sadia
, the UK-based manufacturer of domestic electric water heating equipment, manufactures stainless-steel cylinders at one of its
plants. Cylinders of various sizes are formed, welded and pierced automatically across a production cycle.
installed an electrified monorail system, which moves the cylinders across areas too small for a forklift (in terms of headroom) to get through and features elevator units at the load and unload end of the monorail. The carrying media between the elevator stations is a single trolley unit, powered from the electrified rail. This arrangement has saved time on the manufacturing process as well as space.
Once the item has been moved to where it needs to be for processing, there is often a requirement to use machine vision, for example to position a piece correctly for the next part of a process. This could be welding, fitting into packaging or even rejecting off-spec goods and removing them from the production loop.
The rate of usage of machine vision systems has increased with increased factory automation. Research by the specialist journal Control Engineering and Reed Research Group last year reported that some 89 per cent of respondents expected machine-vision purchases to either be level or increase over the next year.
Another interesting automated process that illustrates how machine-vision systems can be used alongside an automated handler is that of sorting and ordering casino chips - a task once carried out manually.
TCS, a supplier of gaming equipment, has installed a computer-based vision system byActive Silicon
to do just that at a lower cost and higher speed.
One of the problems of sorting casino chips is that colour is all that distinguishes one from another. The system used a Panasonic camera at the front end with a xenon strobe. This lights the chips evenly and 'freezes' the motion of the fast-moving chips so the camera can grab the image as the chips speed by on a conveyor belt.
Software behind this front end synchronises the camera and strobe (from an optical shaft encoder, avoiding vertical synchronisation of the free-running camera) as well as for image capture and processing.
The colour of an individual chip is identified via an algorithm (essentially based on histogram analysis of the colour-space but with some additional manipulation to cope with variation and degradation of the objects over time or factors such as dirt on the chips).
Then the chip is sent to the relevant container using an electromechanical 'pinger' to send them to the appropriate container ready to be returned to the gaming tables.