7. Economic review

With ECM, operating time is a direct function of cathode penetration depth, since machining takes place simultaneously over the entire surface and no preliminary roughing is required. To achieve good reproducibility of dimensions and surface finish, machining depths must be sufficient to erase the memory effect of initial defects (figure 21 ).

To draw up an economic balance sheet, the following parameters must be taken into account:

• the machinability of the material according to its metallurgical state: this parameter has no influence on ECM machining times, but is very important for all other metal removal processes (except EDM);

• surface finish ;

• ...