For fretting tests, only one static load (related to 60% EL) is applied for
5000 cycles. The standard fretting test parameters are a stroke of 50 µm at
a frequency of 200 Hz, as described fully in Annexes A and B. Uncoated
specimens are freshly ground to a surface roughness of Ra < 0.1 µm before
testing [5]. The contact is closed for 10 s and then and opened for another
10 s. At impact, the base pressure of the vacuum is less than 5 × 10–8 mbar, i.e.
the surfaces are not recovered during opening. During a fretting test, a base
pressure of 55 × 10–7 mbar is sufficient, since the change from oxidative to
adhesive wear occurs in the range 0.1–10–3 mbar. The devices are described in
Annex A, and a detail of the fretting test equipment is shown in Fig. 3.