Influence of Machining Strategies and Technological History of Semi-Finished Product on the Deformation of Thin-Wall Elements After Milling

The paper presents an analysis of the influence of machining strategy and the technological history of semi-finished product on the deformation of thin-walled elements made of aluminium alloy EN-AW 2024 after milling. As a part of this research work, five machining strategies are analysed. Additionally, the rolling direction of the plate (longitudinal and transversal) is taken into account as a technological history. During the research, the focus is set on the effects of the machining strategies i.e. HPC, HSM and conventional machining as well as their combinations on the post-machining stresses and deformations. Each of these strategies has a different range of technological parameters, which results in differences in machining efficiency and introduces post-machining stresses to the surface layer of the workpiece that vary in values and nature (i.e. compressive stresses or tensile stresses). The conducted study shows that larger deformations were obtained for transversal rolling direction in each analyzed case. The lowest deformation both for transversal and longitudinal rolling direction were achieved for the HSM and CM strategy

Comparative researches of shearing strength of single-lap adhesive bonded joints 316L steel after „thermal shock”

W pracy przedstawiono badania porównawcze wytrzymałości statycznej na ścinanie zakładkowych połączeń klejowych wykonanych ze stali 316L. Badania miały charakter porównawczy i dotyczyły połączeń klejowych poddanych zmiennym obciążeniom cieplnym oraz połączeń niepoddanych takim szokom. Połączenia klejowe są coraz częściej stosowanym sposobem łączenia w odpowiedzialnych maszynach i urządzeniach eksploatowanych w warunkach zmiennych obciążeń termomechanicznych. Technika klejenia, dzięki postępowi w dziedzinie chemii materiałów adhezyjnych, ciągle się rozwija. Analizowano wyniki badań wytrzymałości statycznej na ścinanie, uzyskanej dla różnych sposobów przygotowania materiału do operacji klejenia. Uzyskane wyniki z przeprowadzonych badań opracowano statystycznie z zachowaniem właściwych standardów naukowych. Zakres badań obejmował stosunkowo krótki cykl zmęczeniowy, wynosił on 200 cykli przy zakresie zmienności -40 °C + +60 °C. Celem głównym badań było sprawdzenie podatności połączeń na zmiany wytrzymałości pod wpływem zmęczenia cieplnego.The article presents results of comparative research of shearing strength of 316L steel single-lap adhesive bonded joints. Adhesive bonding is increasingly being applied as structural joining technique in highly reliable machines and appliances operating in the circumstances of variable thermomechanical loads. The bonding technology, thanks to a progress in the adhesive materials chemistry is continuously developing. Results of static shearing strength of single-lap adhesive bonded joints for different variations of material preparing were analyzed. The obtained results of the conducted research have been elaborated statistically with respect to the appropriate scientific standards. The range of research covered relatively short fatigue cycle, that is 200 cycles in range of temperatures between -40°C and +60°C. Determining the susceptibility of joints to changes of durability by the influence of the thermal fatigue was the main aim of investigations

The study of cutting forces and amplitudes during the milling magnesium alloys

Jednym w ważniejszych celów przedsiębiorstw branży lotniczej jest produkcja coraz lżejszych samolotów/śmigłowców oraz zmniejszenie zużycia paliwa. Jest to możliwe dzięki zastosowaniu elementów wykonywanych ze stopów magnezu. W prezentowanym artykule przedstawiono wyniki badań sił skrawania i ich amplitud po frezowaniu dwóch stopów magnezu AZ31 oraz AZ91HP. Obserwowano wpływ parametrów technologicznych oraz rodzaju narzędzia na wartość sił skrawania oraz ich amplitud. Analiza sił jest ważnym zagadnieniem ze względu na deformację wióra, a co za tym idzie również ze względu na odkształcenia oraz temperaturę w strefie skrawania.One of the most important company objectives for aerospace industry are the production of lighter airplanes/helicopters and reduced fuel consumption. In order to this components made of magnesium alloys should be used. The results of investigation of cutting forces and their amplitudes after milling two magnesium alloys AZ31 and AZ91HP were presented in this article. Influence of technological parameters and the type of used tools on the value of cutting forces was observed. The forces analysis is an important problem due to the deformation of the chip, and therefore also due to the strain and temperature in the cutting area

Methodological problems of temperature measurement in the cutting area during milling magnesium alloys

This paper presents a literature review on temperature measurement during milling of magnesium alloys as well as other structural materials. Methodology and temperature measurement methods used in own tests are discussed in this paper. Selected test results for each method of temperature measurement in the cutting area are demonstrated

Investigations of Adhesive Properties of Polyamide Modified with Friction Reducing Agents

Polyamide is a material used in various industrial sectors. In moving connections, in order to reduce friction between elements made of polyamide, lubrication is used or other substances reducing friction are added, such as molybdenum disulfide. It can be hypothesised that improving the sliding properties of polyamide will adversely affect polyamide’s ability to form effective adhesive bonds. An interesting question is whether a possible unfavourable change in adhesive properties of such modified polyamide will significantly influence the strength of adhesive bonds of this material. This paper analyses the adhesive properties of polyamide with respect to the strength of adhesive bonds. In order to verify the hypothesis, comparative tests of tensile shear strength of bonded doubleoverlap samples were carried out. Tests were conducted in accordance with ASTM D3528. Samples were prepared using Polyamide PA6, PA6 – MoS2, PA6G + oil and EN AW 2024 aluminium alloy. The following technologies were used to prepare the surface prior to bonding: plasma, sol-gel and abrasive jet machining. The summary of the article indicates that adding friction reducing agents to polyamide does not significantly affect the deterioration of its adhesive properties. Samples prepared with sandblasting achieved form 81.8% up to 114% higher shear strength than samples prepared with plasma and sol-gel treatments, disregard of added friction reducing agents to the adhered polyamide material. It is also interesting information of a utility character. A general conclusion can be formulated that the appropriate preparation of the polyamide surface, regardless of its material modification with friction reducing agents, in the technologies analysed, particularly by sandblasting, can ensure satisfactory results of joining the polyamide by adhesive bonding

Zużycie ostrzy frezów podczas obróbki wysokokrzemowego, odlewniczego stopu aluminium AlSi21CuNi

W artykule przedstawiono wyniki badań zużycia ostrzy narzędzi frezarskich podczas obróbki wysokokrzemowych siluminów. Jako przedstawiciela tego rodzaju materiałów wybrano stop EN AC-AlSi21CuNi. Stopy aluminium o zawartości Si > 12% określane są jako trudnoskrawalne, ze wzglądu na zwiększone zużycie ścierne ostrzy, wywołane oddziaływaniem wydzieleń krzemu.Ma to niekorzystny wpływ na proces skrawania, pogarsza jakość i dokładność wykonywanych elementów. Istotne jest więc aby określić trwałość ostrza narzędzi i w momencie jego nadmiernego zużycia przerwać proces skrawania.This paper presents results of tests on the wear of milling cutters resulting from high silicon silumins machining. As a representative for this group of materials EN AC-AlSi21CuNi alloy was chosen. Aluminium alloys containing less than 12 % of Si are classified as difficult-to-cut due to increased abrasive wear of the cutters caused by the influence of silicon precipitates. This affects the cutting process by damaging the quality and accuracy of the manufactured elements. Therefore, it is so significant to determine the durability of the teeth and stop the cutting process when it is being excessively worn

Heterogeneity of Adhesive Joint Properties

This paper presents the results of a study of adhesive joints, focused on the heterogeneity of the properties of the adhesive material in the adhesive joint. The main objective of the study was to determine potential differences in the material properties of adhesive joints made with selected structural adhesives. Due to the impact of the joined material on the adhesive during the curing of the joint as well as the impact of phenomena occurring during the curing of the adhesive, the properties of the adhesive joint may vary along the thickness of the joint. Determining the differences in material properties over the thickness of the adhesive bond is important for more accurate prediction of adhesive bond strength in FEM simulations. In order to observe changes in the material properties of bonds, nanoindentation tests have been carried out on eight adhesive joint bonds made with common structural adhesives used to join sheets of aluminium alloy or corrosion-resistant steel. Basing on the achieved test results, load/unload curves were developed for imprints at characteristic spots of the joints. Distinct differences in the achieved average force value were observed for imprints located in the wall-adjacent zone and in the centre of the adhesive joint; this can be interpreted as areas of the joint with different material structures of higher or lower density of imperfections or porosities. Differences in the load/unload curves for ‘rigid’ and ‘flexible’ adhesives were analysed. The summary includes a conclusion that an adhesive joint is characterised by heterogeneous properties along its thickness

Effect of Abrasive Waterjet Peening Surface Treatment of Steel Plates on the Strength of Single-Lap Adhesive Joints

The paper presents results of comparative study of shear strength of single–lap adhesive joints, depending on the method of surface preparation of steel plates with increased corrosion resistance. The method of preparing adherend surfaces is often one of the most important factors determining the strength of adhesive joints. Appropriate geometric surface development and cleaning of the surface enhances adhesion forces between adherend material and adhesive. One of the methods of shaping engineering materials is waterjet cutting, which in the AWJP – abrasive waterjet peening variant, serves to shape flat surfaces of the material by changing the roughness and introducing stresses into the surface layer. These changes are valuable when preparing adhesive joints. In the study, surface roughness parameters obtained with AWJP treatment, were analyzed in direct relation to the strength of the adhesive joint. As a consequence of the experimental results analysis, the increase in the strength of the adhesive joints was observed in a certain range of parameters used for AWJP treatment. A decrease in shear strength of adhesive joint with the most modified topography of overlap surface was observed

Quality of Samples in Adhesive Joint Testing

The study attempts to assess the quality of various types of samples used in the adhesive joint testing. One great weakness of the scientific research conducted on this type of joints is that the published papers generally do not include an analysis of the samples quality. Although the standards define the tolerances of individual dimensions, detailed reports are in fact rarely presented. Above all, it is very important to control the thickness of the adhesive, which significantly affects the strength of adhesive bonds. It was found that obtaining high quality samples depends mainly on observing the technological discipline and using appropriate instrumentation. The paper presents the standards that should be a reliable model for the scientific research on adhesive joints