Grzegorz Struzikiewicz

This paper presents the results of experimental studies on the influence of the turning process parameters on the values of specific cutting force kc. with the use of different grades of carbide inserts. Three variables were analyzed, i.e. cutting speeds vc, depth of cut ap and feed f, for dry...

Making furniture or furniture elements that account for the needs of children at various stages of development or with psychomotor dysfunctions is very difficult. From the point of view of exploitation and production technology, it is difficult to select a specific material and manufacturing technique. In this article, the results of using the APEKS method, which is a type of Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method, are presented to select the best solution for the production of children’s furniture elements with surface structures similar to those of natural materials. Wood bark was selected as a material that, due to the sensory tactile sensations of dysfunctional children, could contribute to therapy and education. Comparative analysis was performed on the basis of the subtractive and additive methods used for manufacturing furniture products. Precise multiaxis milling of ash wood and 3D printing with fused filament fabrication technology using wood PLA filaments were carried out. The method used to select the best option considered quantitative and qualitative criteria in the assessment. Various parameters characterizing the surfaces were analyzed, such as geometric dimensions, hill heights, valley depths, and 3D surface parameters. The quality and surface roughness (Sa, Sz, Ssk, Sku, Sp, and Sv) parameters obtained based on 3D microscope measurements were determined. A scale of 1 to 10 was used to assess qualitative factors (i.e., usability and aesthetics). Based on the critical values obtained from the coefficient K_cri = 79.36, it was assumed that multiaxis wood milling was the best method for producing furniture elements with the required surface characteristics for use as therapeutic and educational tools for children with dysfunctions. The applied method allowed an effective evaluation of the compared variants of the production of furniture elements for customized applications.

An effective chip formation process is significant for an efficient metal-cutting process. Long continuous chips can lead to scratches on the machined surface, increasing the risk to operator safety and stability of the machining process. The use of chip grooves on cutting inserts allows for control of the chip formation and breaking process during machining. The shape of the rake surface and the design of the chip groove also affect the efficiency of the machining process. The article presents the use of 3D imaging to analyze changes in the selected chip groove shapes depending on the cutting depth a_p = 0.10, 0.25, and 0.50 mm and the angular location of the cutting insert relative to the machined surface of the workpiece (i.e., major cutting-edge angle K = 60° and K = 90°). The analysis methodology was based on the use of 3D image registration and surface shape modeling. In the analysis based on the 3D imaging presented, the novelty was the adaptation of methods typically used to map and model the terrain surface, which have not been used previously in cutting processes. The evaluation of the shape of the chip groove surface was carried out using, e.g., watershed maps and 3D surface maps. The obtained results indicated a significant influence of the cutting depth and major cutting-edge angle on the surface shape, profile, and length of the chip former; chip groove volume; and the theoretical contact area of the formed chip with the cutting insert. It was observed that for small depths of cut, i.e., a_p < 0.25 mm, the chip-curling process may be difficult due to the flattened shape of the rake surface. In addition, the influence of the convexity of the rake surface of the cutting insert on the chip formation process was demonstrated. The results of the experimental research that verified the conclusions are presented. The developed results may be useful in the process of selecting the parameters and conditions of the metal finishing through use of tools with a shaped rake surface.

When turning titanium alloys, it is difficult to ensure the required quality with maximum machining efficiency. A typical problem in the turning process of titanium alloys is to achieve effective breaking and removal of chips from the machining zone. The combination of the new construction of cutting tools and machining methods in the machining of titanium alloys increases the efficiency of the machining. For this reason, the use of tools typical for the Prime Turning method in combination with the high-pressure cooling (HPC) method was analysed. The longitudinal turning of the Ti6Al4V ELI titanium alloy was performed using Sandvik Coromant grade 1115 carbide tools. An increase in the pressure of the cutting fluid to p = 70 bar was used. Measurements of the components of the total cutting force for finishing machining with variable cutting parameters in the range of: feed rates f = mm/rev, cutting depth ap = mm and cutting speed vc = m/min were performed. It has been shown that the values of cutting force are mainly dependent on the feed and the depth of cut. An analysis of the forms of chips obtained is presented. The dependence of the applied cutting parameters on the value of the chip breakage coefficient Cch was determined. The method of searching for the maximum efficiency of the turning process was determined, taking into account the desired value of the chip breakage coefficient.

Development is a result of interactions between biological conditions and the environment in which the developing child lives. The child must receive the right amount of stimuli I – not too much and not too little. Thanks to this, the child gains experience and successfully acquires sensorimotor and cognitive skills. Furniture is part of the physical environment that all young children come into contact with. The aim of the presented study was to check the extent to which furniture designed to support the development of preschool children actually fulfils this function. It was expected that children who would have systematic contact with therapeutic furniture would develop better than children staying in a space with standard furniture. 60 children aged 3 to 6 years participated in the study. Half of the children (two experimental groups of 15 children each) attended a kindergarten that received the designed furniture. These pieces of furniture were located in rooms where children spent time every day – preschoolers had frequent contact with them and could use them spontaneously during free play time. The control groups included children attending preschool with standard equipment. All children were tested twice with a standardised intelligence test (IDS-2, IDS-P, SB5) at a six-month interval. Cognitive function indicators were constructed based on the converted results and used in further analysis. The average values of indicators of the level of cognitive functions were compared in the experimental and control groups. Significant improvement in the functioning of the average child from the experimental group compared to the average child from the control group was noted in the areas of short-term auditory memory, short-term visual memory, conceptual reasoning, gross motor skills and IQ.

The use of high-pressure cooling (HPC) in machining can increase the efficiency and improve process stability through more effective breaking and chip evacuation. Turning tests of the Grade 5 ELI titanium alloy were carried out using cemented carbide tools and taking into account the direction of feeding of the cutting liquid. Measurements of the components of the total cutting force were carried out for feeds in the range f = mm/rev and two angular settings (i.e., angle α = and β = ) of the nozzle. The chip breakage coefficient was determined. It was shown that the cutting force values depended on the feed value, and the angle of feeding of the cutting fluid did not significantly affect the values of the cutting forces. Despite the different forms of chips obtained, the applied method of searching for the best conditions was unsuccessful and no significant effect on the values of the chip breaking coefficient Cch was observed. To determine the best nozzle setting, it is useful to determine the working area of the chip breaker. Due to the shape of the chip, the optimal angular setting for the nozzle that supplied the cutting fluid was α = 60° and β = 30°. In addition, it was observed that the angle of incidence of the cutting fluid jet could affect the chip formation process and support the chip cracking process.

The article presents selected issues related to material quality manufactured by selective laser sintering of AlSi10Mg alloy powder after milling. The workpiece was prepared and machined by down-milling and up-milling with tools made of high-speed steel. Breaches, pores and failure-like cracks on the machined surface were found, which negatively influenced the values of 3D surface roughness parameters. The occurring phenomena were analyzed and proposals for their explanation were made. The results of this research describe the effect of cutting parameters (the feed rate of f = 0.013–0.05 mm/tooth) on the values of parameters describing the surface quality and benchmarks. Topography measurements and 3D surface roughness parameters are presented, as well as the results of microscopic surface analysis. It was found that for aluminum alloy produced by the direct metal laser sintering (DMLS) method, the recommended machining method is down-milling.

This article focuses on the issues related to the machining of DMLS (Direct Metal Laser Sintering) laser sintered parts made of Inconel 718 alloy. Longitudinal turning with CBN (cubic boron nitride) tool inserts is analyzed. The authors made an attempt to establish a procedure to find the optimal finishing cutting parameters while minimizing the specific cutting force and taking into account the machined surface quality criterion. During experiments the influence of cutting data on the values of cutting force and specific cutting force were performed. Moreover, the results of measurements of surface roughness parameters and the results of analysis of chip form are presented as well. Cast Inconel 718 has also been tested for comparative purposes. The variability of the material’s hardening state during machining was found, as well as the variability of the specific cutting force value as a function of the cross-sectional shape of the cutting layer. The values of all components of the total cutting force for turning the material obtained by the additive method are lower than for turning the cast material by approximately 32%. At the end of the article, the authors present an application of the proposed optimization algorithm. It was established that by changing the cross-section shape of the cutting layer, it was possible to perform the turning process at a specific cutting force value of 22% less, which is achieved by reducing the cross-section size.

The article presents selected issues related to the process of turning samples made of the AlSi10Mg alloy with the use of various manufacturing technologies, i.e. casting and DMLS (Direct Metal Laser Sintering). Machining processes of cylindrical surfaces of samples made with these two methods...

This article describes issues related to the machining of parts made of sintered nickel-cobalt alloy. Longitudinal turning with a CBN (cubic boron nitride) tool was analyzed. The results of experiments showed the influence of cutting parameters in the field of finishing machining on the values of cutting forces and specific cutting force, taking into account the wear of the cutting edge. Measurements and analysis of the topography and roughness parameters of the machined surface, as well as the cutting tool wear, were presented. The microscopic examination showed that the average grain size of the sintered nickel-cobalt alloy was 3.22 ± 0.1 (μm). The presence of the hardening state variability of the material during machining, as well as the value of the cutting force fluctuation as a function of the tool wear VB, were stated. The specific cutting force values increased to a small degree for the tool wear in the range of VB = 0–0.2 mm, and reached similar values in the range k_c = 5500–7500 N/mm². The specific cutting force values increased significantly for wear VB > 0.2 mm and were characterized by a large variability. The occurring phenomena were analyzed and several explanations were proposed. A recommendation was developed for the machining of parts made of sintered nickel-cobalt alloy. The Taguchi method was used in the experiment methodology.