CALCULATION OF WEAR RATE A common used equation to compute the wear rate is (Archard,1953).           Vi =ki F s where F is the normal load, s the sliding distance, Vi the wear volume and ki the specific wear rate coefficient. Index i identifies the surface considered. The k-value is given in m3/Nm or m2/N, sometimes in mm3/Nm. From design view the wear displacement h is more convenient than V. With hi =Vi /A, the contact pressure p=F/A where A is the area subjected to wear then:           hi =ki p s The sliding distance s can be replaced by s=v.t where v is the mean value for the slide rate and t the running time. Because the k-value depends just like the friction coefficient on a lot of parameters this factor is to be find experimentally. k  [10-15 m3/Nm] class Examples 0.0001 0.001 0.01 0.1 1 10 100 1000 - 0.001 - 0.01 - 0.1 - 1 - 10 - 100 - 1000 - 10000 0 1 2 3 4 5 6 7 class 2/3: with teflon re-enforced bronze - tempered steel, dry. class 3: hardwearing plastics - tempered steel, moderate load, dry. class 4: bronze (Pb) - tempered steel, after running in, boundary lubricated fatty oil. class 7: grinding. www.tribology-abc.com