Is your conveyor an afterthought or integral to your operation? Mark Smith of baler and conveyor specialist Middleton Engineering considers the role of conveyors in delivering plant productivity and advises how to choose the right baler for your operation.
The humble horizontal baler might not be the most exciting plant machinery, but it plays an essential role in compacting loose and often bulky recyclables to facilitate economic handling, storage and transportation. What is less recognised is the importance of the conveyor, both to feed the baling operation and other production line processes. Like the baling press, the conveyor is ubiquitous across the sector but is frequently taken for granted, with little consideration as to whether it is effective or efficient at what is designed to do.
Given the wide range of conveyor types making the right decision can be challenging. A proper assessment of your site should cover the type and range of materials you will be processing, the weight and volume you expect to handle, as well as the available working space and electrical supply.
Conveyors that are overfilled and continually spilling material or even under filled, are typical. Inefficiencies and production issues will impact the overall effectiveness of the operation and poor design and inappropriate conveyor choice are often the reason. But belt speed, overloading issues, poor synchronisation with other machinery and maintenance issues all play their part.
As the baler won’t deliver uniform, well compacted and consistent bales of material unless the feed conveyor is up to the job, it also means you won’t achieve maximum payload weights for the bales produced.
A smooth and consistent flow of material optimises the loading of the baler and minimises the number of compression strokes and therefore power and time required to achieve bale density and weight. Productivity depends in part on the effectiveness of this relationship. So how can you achieve this?
Of course the conveyor needs to be robust enough for the environment and the weight of the materials to be handled. Reliability is crucial too. The last thing you want is constant shut downs as this inevitably brings other processes to a halt. Planning for your conveyor is crucial.
Experience at St Helier
St Helier Municipal Services on Jersey for example has operated a Middleton ME80 baler with a slider bed on-floor conveyor since 2014. Optimising capacity and throughput is crucial as all recycling is shipped off island for reprocessing, and as volumes have increased it was recognised that an upgrade to the conveyor, adding a new in-floor section with a conveyor pit, would be beneficial.
The chosen solution is a chain conveyor incorporating a two metre in-floor section, rising at an angle of 30° degrees in a swan neck configuration. This makes it both easier and faster to load the baler, improving overall productivity.
Understanding material volumes and throughput is important and solutions like this are designed to feed material at between 3 and 10 tonnes per hour. The in-floor section simplifies and speeds up loading while reducing the level of manual handling, allowing material to be simply tipped or pushed onto the conveyor deck.
Ease of access for scheduled cleaning and maintenance are also important design considerations. These allow debris to be removed and preventative maintenance to be carried out to limit service interruption.
Of course there is a huge range of options. Slider-bed, steel slat, rubber or steel belt, chain driven, inclined, swan neck, fully enclosed, or in floor designs. Generally a chain conveyor will be used where larger volumes of material are being handled. A slider-bed solution is more appropriate for lighter materials and smaller volumes and will generally cost less as it doesn’t need to be as rugged. Products like RDF which can be much denser in volume than card and plastics require higher specification parts for chains, belts, motors and gearboxes. The corrosive nature of the material can also mean higher wear and maintenance considerations.
Achieving a continuous and even flow of material will also depend on factors like belt width, motor sizes – powerful enough to handle the weight of the material to be conveyed – and control systems used.
The temptation to fit a low cost standard option might provide initial savings, but it’s unlikely to deliver the overall performance you expect and is more likely to result in frustration and downtime. Bespoke solutions designed and tuned for your specific environment are superior, and in the long run guaranteed to be more cost effective and safer to use.
With the right design, a conveyor feeds material at the optimal rate for your process, and at a volume and speed that matches other machines or processes. Generally control systems and telemetry should link each piece of machinery so that they work smoothly and harmoniously as one. It is important, therefore, that your supplier is equally competent with both the mechanical and software aspects of your chosen solution. And check that commissioning, testing and tuning are all provided as part of the service.
Written by Gaye Spencer