30/09/2013

Chain Test Standards Include 'Fatigue' Resistance

If you did not already know, changes to ISO 4347 - the international standard governing the manufacture leaf chain used by forklift truck manufacturers to operate a lift truck’s mast - require chain manufacturers to demonstrate that their products offer high levels of ‘fatigue’ resistance (dynamic strength), as well as for ‘breaking load’ (ultimate tensile strength).

At present, chain suppliers are only required to demonstrate that their products comply with guidelines for ‘breaking load’, which indicates the stress or force that can be applied to a chain before it breaks or ruptures. By introducing an element of fatigue resistance testing to ISO 4347, the International Standards Committee require that chains are manufactured with good endurance levels as well as high breaking loads.  This combination will ensure that chain users can specify products for use on their materials handling equipment and other machinery that is fit for purpose and provide the longest life and – therefore – the lowest operational costs.

“A high breaking load alone does not indicate that a chain will have a long life,” says Jim Cameron, technical director of FB Chain Ltd and a member of the International Standards committee tasked with overhauling the current guidelines.  The changes to ISO 4347 require chain manufacturers to show that their chain will withstand a minimum dynamic load for at least 3 million cycles. Jim Cameron adds: “A chain’s ability to provide good ‘fatigue’ resistance whilst maintaining high breaking loads is a far more accurate guide to the chain’s quality and suitability. Most good chain manufacturers will know the fatigue limits of their products and engineers looking to design in or replace a lift truck chain should be taking fatigue limits into consideration as well as breaking loads.”

Anyone tasked with acquiring new leaf chains should ensure that what they are buying has been thoroughly tested for both ‘breaking load’ and ‘fatigue resistance’.

t: +44 (0) 1462 670844