ITF

18 displacement twice per year using 60 mm slip gauges. The accuracy of platen displacement should be ± 0.008 cm. The automated compression machine, including the load cell and platen displacement, should be checked for accuracy against a known traceable reference annually. The accuracy of the load cell should be ± 0.2% over the full scale of its operation (0-1 kN) and the platen displacement should be ± 0.008 cm. Durability. The velocity of ball projection should be checked monthly. The spin rate of ball projection should be checked every two years. The angular velocity and size of the spigots in the felt-wearing device should be checked annually. Tolerances are provided in the Durability Test Method above. The emery paper should be replaced using the following protocol (refer to Figure 7): a. After 16 hours of testing, replace only the pieces labelled number 1 using new pieces of evenly-cut medium grade emery paper (obtained from the ITF) and adhesive spray or adhesive tape applied to the reverse. Ensure that there is no overlap or gap between adjacent pieces. b. After a further 16 hours of testing, replace only the pieces labelled number 2 as described above. c. After a further 16 hours of testing, replace only the pieces labelled number 3 as described above. d. After a further 16 hours of testing, replace only the pieces labelled number 4 as described above. e. Return to step (a). Figure 7. Schematic diagram of the locations of emery paper in the felt-wearing device (net drawing from above). All dimensions are given in centimetres.

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