Two (2) fresh edges of the abrasion bar should be used for each test. If only one specimen is being tested at a time, the next specimen can be abraded on a different part of the hex abrasion bar. Once the entire length of the bar has been utilized, it must be rotated to expose two (2) new edges. After the entire surface has been utilized the hex abrasion bar should be discarded and replaced.
The most common evaluation technique for evaluating abrasion resistance of webbing material is to utilize a CRE-type tensile testing machine equipped with split-drum webbing clamps as described in Federal Test Method 191b, Method 4108.
Average Breaking Strength – For each sample lot, the average breaking strength should be calculated for both the abraded (A) and unabraded (U) lots. The average breaking strength is found by summing each individual sample’s breaking strength and then dividing by the total number of samples in the lot.
Abrasion Resistance (AR) – Abrasion resistance is the percentage of retained breaking force after abrasion. The abrasion resistance can be determined using the following formula:
AR = 100 (A / U)
where AR = abrasion resistance (%)
A = average breaking force of abraded specimen, N (lb)
U = average breaking force of unabraded specimen, N (lb)
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