Bale wire is a major expense in the operational cost of a baler. It may all look the same, but there are differences that can affect productivity more than most realize.
Two factors used to determine quality of bale wire are tensile strength and elongation. Good bale wire (black annealed) will have a tensile strength of 69,000 to 75,000 PSI. Elongation is the ability of the wire to stretch before it breaks. A bale wire with good wire elongation would be that of 25 per cent or more. Less expensive bale wire on average has an elongation factor of 15 per cent. It’s important to note that baler manufacturers produce balers more powerful than earlier models, so these factors are especially critical now.
Bales expand when ejected from the bale chamber and the amount of expansion depends on the products baled. Whenever a metal is worked it will harden and lose some of its elongation and strength. If the original baling wire has low elongation, that of 15 per cent or less, the wire beside the knot on your bale will have insufficient elongation to withstand bale expansion and will break. Proper tensile strength and good wire elongation result in the ability to produce and contain denser bales. Producing denser bales results in lower wire costs (due to less wire use). Denser bales also lower handling costs, storage costs, freight costs, reduce maintenance on baler auto-tier and reduce wear and fuel usage on the forklift.
To properly evaluate the cost of wire it is important to examine the “cost per baled tonne.” Productivity is measured in tonnage so it should also be the unit of measure when costing wire. Using black annealed bale wire as an example, the purchase price for quality bale wire (one with a higher elongation factor and tensile strength) is 44 cents per lb. verses a lower quality wire at 42 cents per lb. The better wire can hold 2,600 lbs. of recyclables (based on a 42-inch x 65-inch bale) so the cost would be $2.00 verses $2.37 per baled tonne of the cheaper wire.
Lower quality wire will typically only hold a bale weighing 2,100 lbs. so there will be a requirement of 15 per cent more wire. In contrast, high-quality wire that costs about two cents more per pound provides a cost savings of about 39 cents per baled tonne. With a production rate of about 3,000 tonnes per month, savings could add up to $13,000 per year or $195,000 during the life span of the baler.
Written by Kathlyn Schoon of Machinex Recycling Technologies, based in Pickering, Ontario. E-mail Kathlyn at email@example.com