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The changing needs of modern manufacturing require a re-examination of the maintenance management role in achieving key cost and service benefits. The development of maintenance requirements is supported by the progress of information technology, which provides new opportunities for the implementation of maintenance processes. The aim of the article is to describe the latest trends in the field of maintenance management from the perspective of the challenges of the fourth and fifth industrial revolution as well as economic, environmental, and social challenges. The five stages of the machine maintenance approach, related to the five industrial revolutions, are characterized, along with the advantages and weaknesses of each machine maintenance approach. The operating data in different operating periods were characterized. Digitalization can empower machine maintenance services by using collected data and advanced technologies to monitor equipment health, diagnose faults, predict and prevent failures long before they occur and ensure performance optimization.

A multilayer structure is a type of construction consisting of outer layers and a core, which is mainly characterized by high strength and specific stiffness, as well as the ability to dampen vibration and sound. This structure combines the high strength of traditional materials (mainly metals) and composites. Currently, sandwich structures in any configurations (types of core) are one of the main directions of technology development and research. This paper evaluates the surface quality of II- and III-layer sandwich structures that are a combination of aluminum alloy and CFRP (Carbon Fiber-Reinforced Polymer) after the machining. The effect of depth of cut (ae) on the surface roughness of the II- and III-layer sandwich structures after the milling process was investigated. The surface homogeneity was also investigated. It was expressed by the IRa and IRz surface homogeneity indices formed from the Ra and Rz surface roughness parameters measured separately for each layer of the materials forming the sandwich structure. It was noted that the lowest surface roughness (Ra = 0.03 µm and Rz = 0.20 µm) was obtained after the milling of the II-layer sandwich structure using ae = 0.5 mm, while the highest was obtained for the III-layer structure and ae = 1.0 mm (Ra = 1.73 µm) and ae = 0.5 mm (Rz = 10.98 µm). The most homogeneous surfaces were observed after machining of the II-layer structure and using the depth of cut ae = 2.0 mm (IRa = 0.28 and IRz = 0.06), while the least homogeneous surfaces were obtained after milling of the III-layer structure and the depths of cut ae = 0.5 mm (IRa = 0.64) and ae = 2.0 mm (IRz = 0.78). The obtained results may be relevant to surface engineering and combining hybrid sandwich structures with other materials.

Digitalization and sustainability are important topics for manufacturing industries as they are affecting all parts of the production chain. Various initiatives and approaches are set up to help companies adopt the principles of the fourth industrial revolution with respect sustainability. Within these actions the use of modern maintenance approaches such as Maintenance 4.0 is highlighted as one of the prevailing smart & sustainable manufacturing topics. The goal of this paper is to describe the latest trends within the area of maintenance management from the perspective of the challenges of the fourth industrial revolution and the economic, environmental and social challenges of sustainable development. In this work, intelligent and sustainable maintenance was considered in three perspectives. The first perspective is the historical perspective, in relation to which evolution has been presented in the approach to maintenance in accordance with the development of production engineering. The next perspective is the development perspective, which presents historical perspectives on maintenance data and data-driven maintenance technology. The third perspective, presents maintenance in the context of the dimensions of sustainable development and potential opportunities for including data-driven maintenance technology in the implementation of the economic, environmental and social challenges of sustainable production.

Cutting inserts made of ceramic materials are used in rough machining processes of Inconel 718. This article compares sintered carbide S205 inserts with 6160 ceramic inserts after finish turning of Inconel 718 with a hardness of 45 HRC. The evaluation focused on insert wear, surface topography and changes in cutting edge radius. The results show differences in the wear of S205 and 6160 inserts. S205 inserts characterize the formation of buildup on the rake face, while 6160 inserts tend to form buildup on the flank face. Furthermore, ceramic 6160 inserts are more prone to notch wear. Surface topography analysis revealed the formation of individual high peaks on surfaces machined with ceramic inserts. The Sa parameter for all cutting conditions studied did not exceed 0.45 µm.

This piece of work deals with the influence assessment of the kind of coating of the cutting inserts and their wear on the dimensional accuracy and the top layer microstructure and roughness of the surface machined with constant cutting parameters vc = 85 m/min, f = 0.14 mm/obr and ap = 0.2 mm. The tests were performed on shafts made of Inconel 718 material under the conditions of finish turning, requiring a tool life of more than 20 min. The cutting inserts of identical geometry made of fine-grained carbide covered with coatings were applied by the PVD and CVD method. The values of the obtained diameter dimensions were assessed in reference to the assumed ones, as well as the values of the surface roughness and stereometry and the microstructure of the top layer. The nature and mechanisms of edge wear and its value expressed by the VBC parameter were also assessed. It was determined in the tests that the machined surface quality defined by the Ra and Sa roughness parameters and the dimensional accuracy were influenced not only by the coating microhardness but also by the method of applying the given coating. The lowest values of the tested roughness parameters were observed for the surface machined with an edge, with the S205 coating applied by the CVD method, which was characterized by the lowest microhardness. The edge with this coating also showed the lowest wear, defined by the VBC parameter, which translated into dimensional accuracy. Furthermore, the edge with the S205 coating also provided the best results with regard to the surface layer microstructure. The least favorable results, both in terms of dimensional accuracy and surface roughness, were obtained for the surface machined with a 1115-PVD-coated edge. The highest wear value was also recorded for this edge.

The objective of the investigation was to identify surface roughness after turning with wedges of coated sintered carbide. The investigation included predicting the average surface roughness in the dry machining of Duplex Stainless Steel (DSS) and the determination of load curves together with roughness profiles for various cutting conditions. The load curves and roughness profiles for various cutting wedges and variable cutting parameters were compared. It has been shown that dry cutting leads to a decrease in friction for lubricated surfaces, providing a small initial contact area where the surface is contacted. The study has been performed within a production facility during the production of electric motor parts and deep-well pumps.

The work deals with the influence of the reach of the applied tool holder on the edge wear, dimensional accuracy and surface quality defined by the topography as well as the roughness of the machined surface. The research has been conducted on specimens made of Inconel 718 in the configuration of sleeves, within the scope of finish turning with constant cutting parameters, vc = 85 m/min; f = 0.14 mm/rev; ap = 0.2 mm. The material under machining has undergone heat treatment procedures such as solution treatment and precipitation hardening, resulting in a hardness of 45 ± 2 HRC. Two kinds of turning holders have been used with the reaches of 120 mm and 700 mm. The tools are intended for turning external and internal surfaces, respectively. The tests have been conducted using V-shaped cutting inserts manufactured by different producers, made of fine-grained carbide with coatings applied by the PVD (Physical Vapour Deposition) and CVD (Chemical Vapour Deposition) methods. The edge wear has been evaluated. The value of the achieved diameter dimensions has also been assessed in relation to the set ones, as well as the recorded values of surface roughness and the surface topography parameters have also been assessed. It has been determined that the quality of the manufactured surface evaluated by the 2D and 3D roughness parameters, as well as the dimensional quality are influenced by the kind of the applied tool holder. The influence is also visible considering the edge wear. The smallest values of the deviations from the nominal dimensions have been obtained for the coated inserts of the range of higher abrasion resistance (taking into account information from the producers). The obtained results show that in predicting the dimensional accuracy in the process of turning Inconel 718 alloy with long-overhang tools, one should consider the necessity of correction of the tool path. Taking into account the achieved surface roughness, it should be pointed out that not only the kind of the tool coating but also the character of its wear has a great influence, particularly, when a long cutting distance is required.

The demand of lattice structures for medical applications is increasing due to their ability to accelerate the osseointegration process, to reduce the implant weight and the stiffness. Selective laser melting (SLM) process offers the possibility to manufacture directly complex lattice applications, but there are a few studies that have focused on biocompatible Ti6Al7Nb alloy. The purpose of this work was to investigate the physical–mechanical properties and the microstructure of three dissimilar lattice structures that were SLM-manufactured by using Ti6Al7Nb powder. In particular, the strut morphology, the fracture characterization, the metallographic structure, and the X-ray phase identification were analyzed. Additionally, the Gibson-Ashby prediction model was adapted for each lattice topology, indicating the theoretical compressive strength and Young modulus. The resulted porosity of these lattice structures was approximately 56%, and the pore size ranged from 0.40 to 0.91 mm. Under quasi-static compression test, three failure modes were recorded. Compared to fully solid specimens, the actual lattice structures reduce the elastic modulus from 104 to 6–28 GPa. The struts surfaces were covered by a large amount of partial melted grains. Some solidification defects were recorded in struts structure. The fractographs revealed a brittle rupture of struts, and their microstructure was mainly α’ martensite with columnar grains. The results demonstrate the suitability of manufacturing lattice structures made of Ti6Al7Nb powder having unique physical–mechanical properties which could meet the medical requirements.

Cortical bone machining is commonly used in craniofacial surgery. The shaping of bone surfaces requires a precise determination of the process’s complexity due to the cutting tool’s defined or undefined geometry. Therefore, research was carried out to assess the impact of the rake angle (γ), clearance angle and depth of cut (d) on the cortical bone machining process. Analysis was carried out based on the orthogonal cutting in three directions. The cutting tool shape was simplified, and the cutting forces and the chip-formation process were monitored. The highest values of the resultant cutting force and shear force were recorded for γ < 0. The specific cutting force decreases with the increase of d. Cutting in the transverse direction is characterized by the highest values of resultant cutting force and shear force. The coefficient of friction depends primarily on the d and takes a constant value or increases with the increase of γ. The tests showed that the chips are formed in the entire range of d ≥ 0.5 µm and create regular shapes for d ≥ 10 µm. The research novelty confirms that even negative cutting angles guarantee controlled cutting and can find wider application in surgical procedures.

This paper presents the methodology of measuring chip temperature in the cutting zone in the rough milling of magnesium alloys. Infrared measurements are taken to determine the effect of variable cutting speed, feed per tooth, and depth of cut on the maximum temperature of chips. Thermal images of chip temperature for a generated collective frame and corresponding histograms are presented. Chip temperatures are presented in numerical terms as median and average values; maximum and minimum values; range; and standard deviation. Box plots are also shown for selected machining conditions. The problems arising during signal recording with a mean emissivity coefficient ε = 0.13, a value which is dedicated during machining magnesium alloys, are discussed in detail. Chip temperatures obtained in the tests do not exceed approx. 420 °C. Therefore, the dry rough milling process carried out with carbide tools with different blade geometries can be considered safe for a wide range of machining parameters. The proposed methodology of chip temperature measurement and result processing is a new and effective approach to safety assessment in the dry milling of magnesium alloys.