a process and system for the treatment of substrates using ions from a low - voltage arc discharge . before coating with an anti - wear layer , the substrates are etched by ion bombardment in order to enhance the adhesion of the anti - wear layer , and the layer which is growing is influenced during the coating by ion bombardment in order to improve the elastic behavior of brittle hard - material layers . the process increases the capacity of the plasma of a low - voltage arc discharge to penetrate the three - dimensional structures of tools , machine parts and items of practical use , and thus effects more uniform treatment by the ion bombardment and therefore better layer properties in indentations . a prerequisite is a hollow substrate arrangement in which the discharge is not prevented from spreading to the substrates . the process , and the system suitable therefore , can be combined with many pvd coating sources , for example with arc sources , cathodic sputtering sources , or a low - voltage arc source .