Wire Fencing (Part 1): Determinants of Wire Quality
Knotted wire fences are fabricated on specialised machines. The input material is typically galvanised steel wire. However, the quality of the input wire used by the Fence Producer is beyond control of the Machine Manufacturer. The problem is that wire strand breakages have been reported during fabrication and subsequent field erection. This is an issue for the Fence Producer because of the lost productivity, and the potential for reputation (brand) damage for both the Manufacturer and Producer. While existing standards do exist for wire, even wire that meets these standards is known to fail during fence fabrication. Thus there is a need to better understand how the quality of wire affects the manufacturabil- ity of fences, and to identify, or if necessary create, a test for wire quality that is able to be conducted by Fence Producers. In this research, samples were obtained from known good and failed fences and wire coils, and subjected to a variety of physical and metallurgical tests. These were then statistically examined and compared to the known fate of the fence, to determine the sensitivity of the test. Four potential tests were evaluated: Tensile strength (UTS), ductility, 3-point bend- ing, microstructural, impact energy, plus a fifth novel new test called linear torsional ductility (LTD). From these tests, it was evident that the linear torsional ductility test was the most sensitive and reliable indicator for wire quality. This paper is part of a collection, with companion papers examining material properties of wire, microstructure, impact energy for wire, knot performance, and the testing of whole fences.
Material Properties of Wire for the Fabrication of Knotted Fences
This paper describes the materials properties of galvanised fencing wire, as used in the fabrication of knotted wire fences. A range of physical properties are investigated: tensile strength, ductility in tension, Young’s modulus, three-point bending, and bending span. A range of commercially available wire products were tested. The results show that most, but not all, high tensile wire samples met the minimum tensile and ductility requirements. Young’s modulus results failed to provide any meaningful insights into wire quality. Flexural modulus results also failed to provide any insight into wire quality issues, with no statistically significant differences existing between acceptable and problematic wire batches. The implications are that premature fence failures are unlikely to be caused solely by reduced tensile properties. Existing test methods, including tensile strength and ductility, are somewhat incomplete, perhaps even unreliable, as measures of wire quality.
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.