Search Results (11)

This paper introduces an Acoustic Emission (AE)-based monitoring method designed for supervising the Abrasive Waterjet Cutting (AWJC) process, with a specific focus on the precision cutting of Carbon Fiber-Reinforced Polymer (CFRP). In industries dealing with complex CFRP components, like the aerospace, automotive, or medical sectors, preventing cutting system malfunctions is very important. This proposed monitoring method addresses issues such as reductions or interruptions in the abrasive flow rate, the clogging of the cutting head with abrasive particles, the wear of cutting system components, and drops in the water pressure. Mathematical regression models were developed to predict the root mean square of the AE signal. The signal characteristics are determined, considering key cutting parameters like the water pressure, abrasive mass flow rate, feed rate, and material thickness. Monitoring is conducted at both the cutting head and on the CFRP workpiece. The efficacy of the proposed monitoring method was validated through experimental tests, confirming its utility in maintaining precision and operational integrity in AWJC processes applied to CFRP materials. Integrating the proposed monitoring technique within the framework of digitalization and Industry 4.0/5.0 establishes the basis for advanced technologies such as Sensor Integration, Data Analytics and AI, Digital Twin Technology, Cloud and Edge Computing, MES and ERP Integration, and Human-Machine Interface. This integration enhances operational efficiency, quality control, and predictive maintenance in the AWJC process. Full article

Titanium aluminide alloys have gained attention for their lightweight and high-performance properties, particularly in aerospace and automotive applications. Traditional manufacturing methods such as casting and forging have limitations on part size and complexity, but additive manufacturing (AM), specifically electron beam melting (EBM), has overcome these challenges. However, the surface quality of AM parts is not ideal for sensitive applications, so post-processing techniques such as machining are used to improve it. The combination of AM and machining is seen as a promising solution. However, research on optimizing machining parameters and their impact on surface quality characteristics is lacking. Limited studies exist on additively manufactured TiAl alloys, necessitating further investigation into surface roughness during EBM TiAl machining and its relationship to cutting speed. As-built and heat-treated TiAl samples undergo machining at different feed rates and surface speeds. Profilometer analysis reveals worsened surface roughness in both heat-treated and non-heat-treated specimens at certain machining conditions, with higher speeds exacerbating edge cracks and material pull-outs. The hardness of the machined surfaces remains consistent within the range of 32–33.1 HRC at condition 3C (45 SFM and 0.1 mm/tooth). As-built hardness remains unchanged with increasing spindle and cutting head speeds. Conversely, heat-treated condition 3C surfaces demonstrate greater hardness than condition 1A (15 SFM, and 0.04 mm/tooth), indicating increased hardness with varying feed and surface speeds. This suggests crack formation in the as-built condition is considered to be influenced by factors beyond hardness, such as deformation-related grain refinement/strain hardening, while hardness and the existence of the α₂ phase play a more significant role in heat-treated surfaces. Full article

The article aims to assess the roughness of parting surfaces in the context of abrasive water jet technology for various materials. The evaluation is based on the feed speed of the cutting head, which is adjusted to achieve the desired final roughness, taking into consideration the stiffness of the material being cut. We used non-contact and contact methods to measure selected parameters of the roughness of the dividing surfaces. The study included two materials—namely, structural steel material S235JRG1 and aluminum alloy AW 5754. In addition to the above, the study involved using a cutting head with varying feed rates to achieve different surface roughness levels required by customers. The roughness parameters Ra and Rz of the cut surfaces were measured using a laser profilometer (laser profilometer). To ensure the accuracy of the laser profilometer, a control roughness measurement was conducted using a contact roughness gauge. The roughness values obtained for Ra and Rz from both measurement methods were plotted on a graph to illustrate their dependencies and were subsequently evaluated and compared. By measuring the roughness parameters Ra and Rz, the study was able to provide insights into the effectiveness of the cutting head’s feed rates in achieving the desired roughness levels. Additionally, by comparing the results of the laser profilometer and contact roughness gauge, the accuracy of the measurement non-contact method used in the study was verified. Full article

We report on a monitoring system based on a high-speed camera for fiber laser fusion cutting. The monitoring system is used without an external illumination retrofit on a conventional cutting head, with the optical path aligned coaxially to the incident laser, permitting a direct, spatially, and temporally resolved detection of the melt pool area in the cut kerf from the top view. The dependence of the melt pool area on laser processing parameters such as laser power and feed rate are thus evaluated for stainless steel, zinc-coated steel, and aluminum, respectively. The signal characteristics of the images captured from the melt pool are examined in the visible spectral range of the emitted secondary thermal radiation from the process zone. An ad hoc developed image processing algorithm analyzes the spectral and geometric information of the melt pool from high-speed camera images and distinguishes between complete and incomplete cuts. Full article

The article presents the results and process analysis of the face milling of aluminium alloy 2017A with the CoroMill 490 tool on an AVIA VMC 800 vertical milling centre. The study analysed the effects of the cutting speed, the feed rate, the actual number of teeth involved in the process, the minimum thickness of the cut layer (h_min), and the relative displacement in the tool-workpiece system D(ξ) on the surface roughness parameter Ra. To measure relative displacement, an original bench was used with an XL-80 laser interferometer. The analysis of relative displacement and surface roughness allowed these factors to be correlated with each other. The purpose of this article is to determine the stable operating ranges of the CoroMill 490-050Q22-08M milling head with respect to the value of the generated relative displacement w during the face-milling process and to determine its influence on surface roughness. The research methodology presented in this paper and the cutting tests carried out allowed the determination of the optimum operating parameters of the CoroMill 490-050Q22-08M tool during the face milling of aluminium alloy 2017A, which are v_c 300 m/m and f_z—0.14 mm/tooth. Working with the defined cutting parameters allows all the cutting inserts in the tool body to be involved in shaping the geometrical structure of the surface, while maintaining a low vibration level D(ξ) > 1 µm, a low value of the parameter h_min > 1.5 µm, and the desired value of the parameter Ra > 0.2 µm Full article

This article deals with the evaluation of selected aspects of abrasive water jet technology (AWJ) in the cutting of abrasion-resistant steel (HARDOX 500) with a thickness of 40 mm. The high abrasion resistance as a typical significant property of this steel ranks it among the special materials that are increasingly used. As the AWJ is a multiparametric technology, selected levels of feed rate, abrasive mass flow and pump working pressure were used in the experiments from the spectrum of technological parameters. For the purposes of evaluation, the examined cut surfaces were documented by a modified photographic method of displaying the cut surface by means of side lighting on the untreated cutting surface. The experimental part evaluates the dependences of selected cutting surface quality parameters (surface roughness and abrasive water jet deflection) on selected important technological parameters of the production system with AWJ technology (abrasive mass flow, technological head feed rate and pump working pressure). Based on the evaluation of the experiments, regression models were created to interpolate and extrapolate data to compare or supplement existing solutions in the field of research and as a basis for optimizing operating costs and increasing the efficiency of production systems with abrasive water jet technology. Full article

The semi-conical shell workpiece is a special kind of thin-wall part that is commonly used in aerospace and mold industries. Due to the special stiffness distribution and weak rigidity for the area with a large radius, the machining quality of the semi-conical shell is sensitive to both cutting force and vibration. Conventionally, constant conservative machining parameters are chosen to ensure the workpiece deformation and surface quality, which will reduce the machining efficiency. Based on the cutting force and vibration response simulation of the whole milling process. A feed rate variation strategy is proposed for the ball head end milling process of the semi-conical shell workpiece. The cutting force, dynamic performance and stability prediction are obtained considering the shape and boundary conditions of the workpiece and the contour tool path of the milling process. Variable feed rate is used in the milling simulation to find the harmony between machining quality and efficiency. User-defined vibration amplitude and another user-defined cutting force threshold are used to find the optimal feed rate for each simulation segment. Both continuous and discrete feed rate variation strategies are proposed, and the improved discrete feed rate variation is applied in the milling experiment. About 25% of the consumed time is saved with almost the same machining quality by the experimental results. Full article

Austenitic stainless steel belongs to the best oxidation-resistant alloys, which must function effectively and reliably when used in a corrosion environment. Their attractive combination of properties ensures their stable position in the steel industry. They belong to a group of difficult-to-cut materials, and the abrasive water jet cutting technology is often used for their processing. Samples made of stainless steel AISI 304 has been used as the experimental material. Data generated during experiments were used to study the effects of AWJ process parameters (high-pressure water volume flow rate, the diameter of the abrasive nozzle, the distance of the nozzle from the material surface, cutting head feed rate, abrasive mass flow, and material thickness) on surface roughness. Based on the analysis and interpretation of all data, a prediction model was created. The main goal of the long-term research was to create the simplest and most usable prediction model for the group of austenitic steels, based on the evaluation of the practical results obtained in the company Watting Ltd. (Budovateľská 3598/38, Prešov, Slovakia) during 20 years of operation and cooperation with customers from industrial practice. Based on specific customer requirements from practice, the publication also contains specific recommendations for practice and a proposal for the classification of the predicted cut quality. Full article

In industries such as aerospace and automotive, drilling many holes is commonly required to assemble different structures where machined holes need to comply with tight geometric tolerances. Multi-spindle drilling using a poly-drill head is an industrial hole-making approach that allows drilling several holes simultaneously. Optimizing process parameters also improves machining processes. This work focuses on the optimization of drilling parameters and two drilling processes—namely, one-shot drilling and multi-hole drilling—using the Taguchi method. Analysis of variance and regression analysis was implemented to indicate the significance of drilling parameters and their impact on the measured responses i.e., surface roughness and hole size. From the Taguchi optimization, optimal drilling parameters were found to occur at a low cutting speed and feed rate using a poly-drill head. Furthermore, a fuzzy logic approach was employed to predict the surface roughness and hole size. It was found that the fuzzy measured values were in good agreement with the experimental values; therefore, the developed models can be effectively used to predict the surface roughness and hole size in multi-hole drilling. Moreover, confirmation tests were performed to validate that the Taguchi optimized levels and fuzzy developed models effectively represent the surface roughness and hole size. Full article

This article presents the results of experimental studies of the impact of centrifugal shot peening parameters on the roughness, microstructure, and microhardness of the surface layer of laser-cut C45 steel parts. Residual stress distributions and the presence of iron oxides on the surface of these elements were also examined. Centrifugal shot peening tests were performed on an FV-580a vertical machining center while using a specially designed peening head. The parameters that were varied during centrifugal shot peening included tangential speed of the tool v_g and feed rate v_f. The use of centrifugal shot peening for finish machining of laser-cut C45 steel parts allowed for obtaining a four-fold reduction in the surface roughness parameters Ra and Rz. As a result of shot peening, the geometrical structure of the surface of the steel parts was modified and it acquired new beneficial features, such as large values of the rounding radii of the micropeaks and high material ratios (Rmr_max = 92%). At the same time, the surface layer was hardened (microhardness increased by 16%) and a compressive residual stress layer was produced on the surface of the workpieces. Additionally, as the shot impacted the processed surface, combustion products were “blasted” or “sheared” off it. Shot peening using the proposed technique can be successfully performed while using CNC machines. Full article

The paper is an evaluation of the surface roughness of various materials produced by water jet cutting (AWJ, abrasive water jet). A 3D laser profilometer developed at the Department of Design and Technical Systems Monitoring at our University was used in roughness measurement. To verify the values measured by the laser profilometer, another measurement was performed using a 2D contact roughness meter. The tests were done on aluminum and stainless-steel materials, respectively. Six samples were produced; three made of stainless steel and three made of aluminum. All samples were produced at a different feed rate of the cutting head. This was adapted to the different roughness required, per the manufacturer’s material data sheets. Varying rates of separation translated into different qualities of the surfaces under evaluation. The evaluated roughness parameters were Ra and Rz. Dependencies were plotted in the chart based on the values measured, which were then compared and evaluated. Full article