Technical Help
Why does wire untwists at the knot?
Balers with automatic tiers that use black-annealed, high-strength baling wire can incur problems in which the wire unties at the knot after the bale is produced.
It is our opinion that the primary cause of this problem is that the wire tensile strength is too low in either one or both of the wires making the knot. The wire specifications require a tensile strength of 65,000 - 75,000 psi in order for the knot to remain tied.
From experience, we have observed knots untying where one wire has a tensile strength of 75,000 psi while the other wire making up the knot has a tensile strength considerably less than this, for example, 60,000 psi. Under these conditions, the lower strength wire pulls out or unties from the higher strength wire. In some cases, by checking the tensile strength of all coils, the baler operator can "match up" wires with similar tensile strength, even if they are of lower tensile strength than normal, and thereby produce a satisfactory knot.
If you are having problems with your baling wire untwisting at the knot and would like us to check the tensile strength of your wire, please send us two, 12" to 14" samples of unused wire. We will test the wire for tensile strength and elongation free of charge, even if the wire was not produced by us.
