Type of Belt edges used in rubber conveyor belts
Belt edges used in rubber conveyor belts – There are three basic types of belt edge – molded, sealed and plain cut edge. The importance of which type to use is vastly underrated. Choosing the wrong type costs many conveyor operators a great deal of wasted time and money, especially when specifying that the belt must have full molded edges even when there is no practical or technical benefit.
Molded edges
Many years ago, molded edges were the norm for multi-ply belts because cotton was being used as the reinforcing fabric. Having a molded edge was therefore essential in order to prevent moisture penetrating the cotton fabric and causing it to rot.
However, since the inception of synthetic belt carcasses using polyester and polyamide, this problem effectively no longer exists so belts with cut and/or sealed edges are now the most commonly used belt edge type. Despite this, many buyers continue to needlessly specify molded edges even when they are not needed.
Sealed edges
The alternative and most commonly used belt edge type is the ‘cut & sealed edge’ or simply ‘sealed edge’. The majority of fabric multi-ply belting is held in stock in a range of the most commonly used standard widths by manufacturers, distributors and traders. To maximize the efficiency of production and minimize cost, these standard width stock belts are usually made as wide as the manufacturing machinery will allow. These are known as ‘slabs’ which are then cut to narrower widths. The belt edges are then sealed during the slitting process.
Steel cord construction belts
In the case of steel cord belting it is necessary to use molded edges in order to prevent moisture penetration into the carcass which, over time, would cause the steel to corrode. This also applies to steel reinforced fabric ply belts. Belts with more specialized cover grades (such as fire-resistant for example), hi-performance carcass constructions or simply a non-standard width requested by the customer that therefore have to be custom-made will also naturally have molded edges.
