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The adaptive control of metal cutting processes is a logical extension of the CNC systems. In CNC systems of metal-cutting processes the machining variables (e.g., the cutting speed and feedrate) are prescribed by the part programmer. The determination of these variables depends on experience and knowledge regarding the workpiece and tool materials, coolant conditions, and other factors.The determination of these operating parameters depends on experience and knowledgeregarding the workpiece and tool materials, coolant conditions, and other factors. By contrast,the main idea in adaptive control is the improvement of the production rate, or the reductionof machining costs, by calculation and setting of the optimal operating parameters duringmachining itself. This calculation is based upon measurements of process variables in real time and is followed by a subsequent on-line adjustment of the machining variables subject to constraints with the objective to optimize the performance of the overall system.The adaptive control is basically a feedback system, in which the operatingparameters automatically adapt themselves to actual condition of the process. AC system formachine tools can be classified into two categories:1.Adaptive control with optimization(ACO);2.Adaptive control with constraints(ACC);ACO refers to systems in which a given performance index (usually an economicfunction) is extremized subject to process and system constraints. With ACC, the machiningparameters are maximized within a prescribed region bounded by process and systemconstraints, such as maximum torque or power. ACC systems, however, do not use aperformance index. In both systems an adaptation strategy is used to vary the operatingparameters in real time cutting progresses. Although there has been considerable research onthe development of ACO systems, few, if any, of these systems are used in practice. The major problems with such systems have been difficulties in defining realistic indexes of performance and the lack of suitable sensors which can reliably measure on-line thenecessary parameters in a production environment. The objective of most AC systems isimprovement in productivity, which is achieved by increasing the metal removal rate (MRR)during rough cutting operations. The increases in productivity range from approximately 20 to 80 percent and clearly depend on the material being machined and the complexity of the part tobe produced.

The aim of this research is to find possible ways to recycle and re-use industrial solar cell scrap. The work is concentrated on cells which are broken, damaged or rejected during the manufacturing process, which accounts from 2 to 3 percent of whole production on average. Different chemical methods have been suggested for the recovery of pure valuable elements from damaged or worn cells, while the technology presented in this paper utilizes industrial solar cell scrap to produce secondary value products. Crushed industrial waste of different fraction sizes was analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) methods. Tungsten inert gas welding (TIG) has been chosen as the coating formation process. Proper parameters: current 55 A, voltage 19 V, gas flow rate 5 l/min, torch tilt angle 80–85° were selected experimentally, as parameters of common welding are not suitable for the deposition. The chemical composition and transition of chemical elements towards the substrate showed sufficient adhesion and smooth distribution of elements. Alongside with aforementioned methods, mechanical tests were accomplished, showing that damaged solar cells industrial scrap could be used as a source of alloying elements to compose the coating. The hardness of produced coatings as deposited reached 39 HRC (microhardness 2 GPa) on average. Formed coatings could serve for various applications, however further in-depth research is necessary. As suggested, the wear test method is too aggressive for this type of surface. Nevertheless, coatings based on industrial solar cell scrap showed a mass loss two times lower on average than normalized structural steel S355 substrate in rough abrasive conditions.

Submerged arc welding (SAW), plasma transferred arc welding (PTAW), and tungsten inert gas welding (TIG) technologies were used to produce austenitic stainless steel (SS) and nickel alloy (Ni) matrix based hardfacings without reinforcement and reinforced by Cr3C2–Ni cermet. As a substrate material normalized structural steel S355 has been chosen. Mechanical properties of produced hardfacings were assessed in terms of hardness (HV/30) and wear resistance tests. The latter property was analysed under different wear conditions: two-body (ASTM G132) and three-body (ASTM G65) abrasive wear tests. Microstructure and phase evolution were analysed by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD), respectively. Cermet particles in all the conducted tests proved its’ selection – hardness and wear resistance of the reinforced hardfacings substantially increased. The addition of Cr3C2–Ni cermet increased the hardness twice on average in all utilized technologies leading to the higher wear resistance in further tests. Tendency of wear rate reduction is less expressed in SAW hardfacings, but in PTAW and TIG cases the strengthening effect is obvious: 8.6 and 8.1 times higher wear resistance of SS and Ni based PTAW hardfacings, respectively, and 7.5 and 4.8 times higher for TIG hardfacings. XRD analysis supported wear tests results proving the formation of the complex compounds.