Recommendations for use:
A great problem in the operation of handling equipment is the insufficient cleaning of the belt or the necessity of continuous adjustment of the position of the pulley sets.
Therefore, when using belt conveyors, apart from the basic equipment, it is also worth remembering about additional devices supporting their operation and paying attention to their operational parameters. This increases system durability, reduces noise and dust levels and prevents production downtimes. However, the lack of this type of equipment or the use of unproven subassemblies results in a significant operating nuisance and an increase in the operating costs of conveyors.
Our goal is to raise the standard of manufacturing and operation of belt conveyors by using NITROLL equipment, which reduces operating costs.
We focus on the two most common problems and their solutions:
- Effective cleaning of the belt from residues of the load
- Guiding the belt running to the lateral direction of the conveyor
- Cleaning of belts from residues of the load:
The belt that is badly cleaned from residues of the load:
- Material loss and reduced conveyor capacity.
For example: for an uncleaned belt covered with a 0.1-mm (0.0001 m) layer of the load and:
– belt width B=1,000 mm (1 m)
– feed width = 0.8 B = 800 mm (0.8 m)
– belt speed = 2.50 m/s
– operating time = 16 h/d, 250 d/year
– amount of the load that spontaneously falls off the vibrating belt = 30%.
The total amount of the load gathered in an uncontrolled way under the conveyor route will be as follows:
0.0001 m x 0.8 m x 2.50 m/s x 3600 s x 16 h/d x 250 d/year x 0.3 = 864 m³/year
- Difficulties in starting the conveyor (reduced friction coefficient).
- Increased wear of bearings and shells of idlers and pulleys.
- Axial misalignment of the belt (destroying the belt edges, damaging the conveyor structure).
- Reduction of the corrosion resistance of the conveyor structure.
- The need for employees to clean the route and structure of the conveyor.
- Operating breakdowns due to the system malfunction.
When analysing the cost-effectiveness of a scraper application, it is worth comparing the cost of purchase with the operating costs (costs of scraper replaceable components, traditional intensive cleaning of the conveyor, material losses, component wear and production downtimes).
According to comparative research carried out in 40 companies by the Swedish Royal Institute of Technology, the amount of material not removed on the drop pulley (due to the use of poor quality scrapers) – equals to 0.2% of the transported load and the total cost of losses resulting from this fact is USD 1.10 per tonne of the transported load.
In order to eliminate this problem, it is advisable to use scrapers suitable for the type of the load and the characteristics of the conveyor. Those scrapers should guarantee a high cleaning efficiency of the belt without the risk of abrasion of the loading cover.
- Guiding the belt to the conveyor axis:
The belt should be guided along the conveyor axis during its movement, within the tolerance of lateral running. The permissible misalignment may be max. 5 – 8% of the belt width.
The belt misalignment that exceeds the permitted misalignment leads to losses resulting from:
- abrading and destroying the belt edge and conveyor structure,
- spreading the transported load,
- increasing the movement resistance (up to 16% of the total resistance to movement of the conveyor),
- operating breakdowns caused by system failures.
In order to prevent these phenomena, it is worth using belt guiding devices whose centring force that results from appropriate chamfering of an idler or a set of idlers appears only at the moment of reaction to the misalignment of the belt (as opposed to the so-called advance sets). It is necessary to use such belt centring devices that only operate (automatically) when the belt leaves the conveyor axis in excess of the permitted safe limit.
It should be emphasized that the conveyor belt should be particularly protected because it is the component with the lowest durability and the cost of its purchase is 30 – 50% of the cost of the whole conveyor.
