Definitive Guide for Choosing the Right Conveyor Belt
Because choosing the right conveyor belt for your conveyor system will lead to effective production, a longer operational lifetime and component compatibility.
Here are a number of tips to identify if your conveyor belt is being subjected to additional wear and tear or abrasion:
• Check that your operating tension (PIW) is at the correct level and that it meets the load capacity. If unsure, seek outside assistance.
• If your power load has increased lately, check to see if your conveyor belt idlers are catching or succumbing to wear and tear.
• If the product load has increased, it is likely that the impact rating has also increased and the surface of the conveyor may need upgrading to protect the belt.
• If the product weight has increased, check to see if its troughing abilty is still appropriate or whether it is catching on the pulleys, idlers, impact beds and frames.
• Check to see that you have installed the appropriate conveyor width to match your pulleys, drums and loading zones. If not, replace the items, as this is more cost effective than replacing the entire conveyor belt.
• Check to see how far the actual conveyor has to travel. If this has been changed, then the belt may need adjusting by lengthening or shortening, adjusting the tension and/or adjustment of the conveyor to adapt to the product weight.
• Check your cover of your conveyor belt to see if it is still able to manage the present load or load fall – if it is showing signs of wear, then the cover may need reviewing.
If you’re struggling to understand which of these issues needs resolving then you may need an audit to identify where your system has weaknesses. This will help to avoid higher costs incurred in the future.
An Objective Understanding of your Conveyor System
To quickly understand potential problems in the future or to address an immediate issue, All State Conveyors are able to recommend a suitable conveyor belt for a new system or a replacement of an existing system. We can conduct an objective audit of the system and all the relevant operating conditions to understand where your issues lie. They are able to also customise your conveyor belt if necessary.
Please Note: When faced with anti-static or high risk of fire situations in underground mining, to ensure you have a safer work environment, All State Conveyors recommend you utilise a FRAS ‘E’ belt only
All State Conveyor belt specialists will expand further on the 7 key criteria you should take into account when choosing an appropriate belt for your system.
#1. Operating Tension (PIW)
There are many factors that come into play when dealing with tension in a belt carcass. The tension member fibres provide strong longitudinal strength that moves the load and withstands potential torque from the system to start up. Belt tension is calculated with a simple formula that nominates the required PIW (pounds per inch of width) to acquire the correct and safe tension level. A belt carcass has two important strength ratings which identify the optimum working tension. These are referred to as the Maximum Working Tension and the Ultimate Tensile Strength – factors that can cause the belt to fail or tear.
S x W
The working strength of the carcass is determined by dividing the ultimate strength by the service factor. Both these values can be readily obtained from All State Conveyors to assist you to make the right decision.
When choosing a belt, it is important to monitor the stopping and starting conditions to gauge whether the excess tension is viable and not overly excessive. The maximum working tension of your belt needs to equate to or not exceed more than 150% of the maximum tension of the whole system in standard working conditions, to ensure greater longevity.
#2. Minimum Pulley Diameters
Pulley diameters play an important role with the ultimate functioning of your system. The thickness and the number of plies of a belt can cause stiffness of rigidity. In order to maintain the proper strength and tension, each belt will require a minimum diameter for the pulleys. As the belt is the more expensive component, the pulley selection should be adjusted to accommodate the belt.
Using the appropriate sized pulley will allow the belt to operate at its full tension rating without placing undue stress and compression on the inner plies. Minimum pulley diameters for conveyor systems are calculated for various belt carcasses and differing tension ratings.
#3. Load Support
When the conveyor belt is operational and moving, a flat belt carcass should maintain a constant rigid and or troughed state whilst functioning in order to support the load capacity and to constantly bridge the idler junction gaps. The load support values are predetermined for conveyor belts, which are based on the number of plies and the type of belt. As your loads may vary, it is important to choose the right belt carcass to support the load it must bear.
Once again, depending on what load needs to be supported, conveyor belts can be adjusted by 25 degrees to carry larger loads by being shaped into a trough.
The choice of belt to support your load is extremely important , as even though it needs to be flexible, it needs to transverse between the idlers and not loose its rigid shape and sag. If it does, it may cause cover and carcass wear and reduce the life of the belt.
Trough shaped belts create greater flexibility on mine and quarrying sites, particularly if there is a need to vary the loads occasionally. Troughing ability is extremely useful for the carrying of smaller rocks or finer particles such as sand and aggregate, which can fall from a flat surfaced belt.
In order to create a toughed shape belt, there needs to be enough pliability and suppleness, with the right amount of plies within the belt itself to conform to the shape of the idlers in their supporting frame work.
It is important to understand the load support, minimum width and angle the trough must maintain when empty and the maximum when functioning with a load. All State Conveyors have this information readily available for you if need be.
#5. Transition Distance
It is essential to understand the exact transition distance your belt travels from being fully troughed (over an idler) to becoming completely flat (over the pulley). If the distance is incorrect, it can lead to a number of problems. The outer edges of the belt may become stretched if the distance is too short. If the tension is too great and the elastic limit of the belt surface is surpassed, the rubber and carcass will be unable to retract and retain its original shape. The reshaping of the belt from these 2 issues can cause reduced belt life and lead to the belt not fitting on the pulleys properly and increasing wear and tear. ASC can advise on the exact distance the belt should be utilised.
#6. Impact Rating
How far your load falls is a large factor in determining what sort of impact your belt will sustain over a certain period of time. Your choice of the number of piles, type of fibre weave design and tension member all contribute to the ability to absorb the impact and for the belt to resume its original state. It is important for ASC to understand the quarry or mining sites operational loading and impact procedures and standards, as well as the size and type material being conveyed to recommend the appropriate conveyor belt.
There is an impact rating which is formulated by the drop to belt ratio which should be adhered to, which ASC can supply if need be.
#7. Conveyor Belt Covers
The main considerations are as follows:
- the type of material being transported
- the load factor and drop to belt ratio
- the quality of the cover
- the ‘fit for purpose’ factor
- the appropriate elastomers
- the overall thickness
Selecting the appropriate cover is not a one size fits all process, it depends on what is being conveyed. The material may be sharp and abrasive with large deep penetration points, corrosive and need to protect the cover from wear.
The weight and how far the material or rock will drop to meet the belt will also need to be considered. The greater the weight and the longer the drop, the higher the potential for the belt to fatigue and not resume its original shape. This can also increase the propensity for tears and large areas of abrasion.
Dependent on your system, most of the wear occurs on the top surface of your conveyor belt and a smaller amount on the bottom cover. The quality of the belt cover is a very important factor in ensuring that the top surface remains in good working order for the long-term sustainability of your conveyor belt. The better quality of your belt cover means it lasts longer.
If the cover is fit for purpose, it will not be subjected to as much wear and tear and will have a greater life expectancy. The strength and construction of the cover is determined by the elastomers, which are capable of withstanding most unfavourable material composition being conveyed. For instance, there is a particular composition of elastomers designed to withstand tree sap from damaging the belt cover.
There is another important ratio, 3 to 1 which should be used when determining the thickness of the top and bottom covers. An accurate summation of cover thickness can be determined by using the belt frequency factor. The more often you use it, the shorter the life of the belt.
If your material is overly abrasive, the conveyor should be made shorter with a sustainably thicker belt. That being said, the cover’s resistance to abrasion is more important than the thickness when it comes to durability. ASC partners with manufacturers who believe in overall belt durability over belt thickness, as this can add additional weight to the system and increase overall power consumption.
At All State Conveyors, we have extensive knowledge and understanding of the conveyor belt industry. We provide custom made, heavy duty, fit-for-purpose and standard belts with numerous covers.