Chainmaking

Chain-making is an important mechanical industry. For the past twenty years from 15,000 to 20,000 tons of chain have annually passed inspection, and withstood the regulation tests in England. The manufacture of very small chains affords employment to women and children but all heavy work requires the skilled labour of men trained to this special smiths' work. The links in a chain are either unstudded or studded. The former type of link is made of a bar of proper length and thickness, heated to a suitable temperature, and bent into a loop so that the ends meet. These ends are then welded together, and while still soft the link is worked to the required shape, and a finish is given to the weld. Additional links are threaded on to the previously-made one before being welded. The studded link, used for chains of over one inch diameter, is closed at the side and strengthened laterally by a stud welded across its width, thus dividing the link into two parts. Chains must be capable of resisting sudden shock; their material must, therefore, not be brittle. They must also withstand heavy, steady loads; thus the iron employed in their manufacture is required to possess great tensile strength, as well as considerable ductility. Lloyd's tests consist of the application of a standard stress to every 15-fathom length of chain, sufficient to exhibit weakness in any part without injuring any satisfactory specimen. Also pieces of chain are cut at random from any part of each length, and subjected to a stress 50 per cent. above the standard, the cut portion being linked up again. These tests proving satisfactory the quality of the chain is certified.