The regulated quality parameters of the products are ensured by different technologies. In particular, sustainable manufacturing provides important requirements and main tasks for Industry 4.0/5.0. The priority directions to improve the sustainability of product manufacturing are associated with the simulation of machining processes by cutting, complex assurance of the technological system at parts machining, and the development of practical techniques for reliable measurement of the technological parameters of products. In the paper, a developed technique is implemented to estimate the surface layer of aluminum castings after step-by-step machining using rough and finish milling using the LM-hardness method. The degree of the degradation of the surface material of the workpieces is analyzed comprehensively using indicators of the criterion of surface homogeneity: coefficient of variation ν; Weibull homogeneity coefficient (m), and indicators related to it: material constant Am, technological damageability D, and the intensity of increasing of the technological damageability jD. It is established that step-by-step machining of workpieces by rough and finishing milling does not change the structurally homogeneous state of the material of the blanks. An increase in power loads at rough milling with manual feed of the working table of the metal-cutting machine creates a gradient structure in the workpieces. It increases the susceptibility to damage of the surface layers of workpiece material. Reduction of power characteristics at finish milling with automatic feed of the working table of the metal-cutting machine reduces the number of structural stress concentrators that ensure regulated parameters of products. Further investigations in that research direction are offered.