Multi-function scratch tester

Scratch testing and especially multi-pass testing involve applying repeated movements of an indenter over a surface. Many tests are needed to produce a statistically reliable result. The tests need to be performed under conditions of known constant temperature and humidity, because variations in these parameters may affect the results. Specialized high contact pressure, low speed friction testing can be achieved using scratch-tester-type loading geometry; however, for the data to be meaningful in comparative tests, environmental control is again essential. Presently, most scratch testing is carried out in non-controlled environments and often without an adequate number of tests. A new machine has been designed and constructed to take account of the shortcomings of conventional scratch testers. A computer controls the environment conditions, the positioning and motion of the indenter, and records the data from sensors. A large sample locating surface is available to allow many samples to be examined in the same batch. This paper presents the design, construction and the additional uses of this new testing apparatus.