Strain and strain-hardening analysis of formed parts produced by multi-pass metal spinning

U članku se daju rezultati eksperimentalnog istraživanja usmjerenog na analizu radijalne i tangencijalne raspodjele deformacije i utjecaja otvrđivanja plastičnom deformacijom površinskih slojeva šupljih dijelova od metalnog lima proizvedenih višeslojnim utiskivanjem (rotacijskim oblikovanjem) metala. Korišteni su tanki limovi od čelika EN 10025-94 (ISO 630-80), debljine 1 mm. Rezultati istraživanja potvrđuju minimalni utjecaj anizotropije materijala na radijalnu i tangencijalnu raspodjelu deformacija i relativno značajan utjecaj anizotropije materijala na otvrđivanja plastičnom deformacijom površinskih slojeva utiskivanih dijelova. Ustanovljeno je da veće otvrđivanje plastičnom deformacijom postoji u smjeru 90° prema smjeru valjanja lima nego u smjeru 0°.The paper presents results of experimental study focused on the analysis of radial and hoop strain distributions and effect of strain-hardening of the surface layers of sheet metal hollow parts produced by multi-pass metal spinning. The thin sheets of 1 mm thickness, steel EN 10025-94 (ISO 630-80), were used for experimental study. The results of the study confirm minimal influence of the anisotropy of material on radial and hoop strain distributions and the relatively significant influence of the material anisotropy on the strain-hardening of the spun part\u27s surface layers. It is found higher strain-hardening in the direction 90° refer to the rolling direction of the sheet compared to the direction 0°

The Effect of Process Parameters on Surface Finish of Metal Spun Parts

The paper brings the results of surface finish analysis of formed parts produced by CNC multi-pass conventional metal spinning. The influence of mandrel speed, spinning roller feed and workpiece geometry on the surface finish of formed parts made of mild steel type of EN 10025-94 (ISO 630-80) have been studied by profile and 3D surface parameters evaluating. For the study, the full factorial design of experiment (33) was used and ANOVA (Analysis of Variance) was carried out. It is shown that the optimal roller feed exists within the range of minimal and maximal experimental feed values and the surface roughness measured in different areas of experimental samples (radius R10, conical area, cylindrical area) indicates that the higher surface roughness occurs at the conical surfaces

Study on surface roughness, morphology, and wettability of laser-modified powder metallurgy-processed Ti-graphite composite intended for dental application

In this study, the surface laser treatment of a new type of dental biomaterial, a Ti-graphite composite, prepared by low-temperature powder metallurgy, was investigated. Different levels of output laser power and the scanning speed of the fiber nanosecond laser with a wavelength of 1064 nm and argon as a shielding gas were used in this experiment. The surface integrity of the machined surfaces was evaluated to identify the potential for the dental implant’s early osseointegration process, including surface roughness parameter documentation by contact and non-contact methods, surface morphology assessment by scanning electron microscopy, and surface wettability estimation using the sessile drop technique. The obtained results showed that the surface roughness parameters attributed to high osseointegration relevance (Rsk, Rku, and Rsm) were not significantly influenced by laser power, and on the other hand, the scanning speed seems to have the most prevalent effect on surface roughness when exhibiting statistical differences in all evaluated profile roughness parameters except Rvk. The obtained laser-modified surfaces were hydrophilic, with a contact angle in the range of 62.3° to 83.2°.KOMPLAS; Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGA, (026STU-4/2023); Vedecká Grantová Agentúra MŠVVaŠ SR a SAV, VEGA, (2/0054/23)VEGA [2/0054/23]; KEGA [026STU-4/2023]; STU Grand Scheme for Support of Young Researcher

Laser surface texturing of tool steel: textured surfaces quality evaluation

In this experimental investigation the laser surface texturing of tool steel of type 90MnCrV8 has been conducted. The 5-axis highly dynamic laser precision machining centre Lasertec 80 Shape equipped with the nano-second pulsed ytterbium fibre laser and CNC system Siemens 840 D was used. The planar and spherical surfaces first prepared by turning have been textured. The regular array of spherical and ellipsoidal dimples with a different dimensions and different surface density has been created. Laser surface texturing has been realized under different combinations of process parameters: pulse frequency, pulse energy and laser beam scanning speed. The morphological characterization of ablated surfaces has been performed using scanning electron microscopy (SEM) technique

Laser beam machining of commercially pure titanium: influence of process parameters on surface roughness

Laser machining is one of the most widely used advanced machining processes used for creating new surfaces, structures, cavities and also complex electro-mechanical devices, usually with very small dimensions, by laser radiation. Optimal selection of process parameters is highly critical for successful material removal and high machine surface quality. In the paper the relation between process parameters and machined surface quality characteristics is experimentally studied applying the five axis highly dynamic laser precision machining centre Lasertec 80 Shape equiped with the pulsed ytterbium fibre laser (wave lenght 1064 nm, maximal average output power 100 W) and CNC system Siemens 840 D and commercionally pure titanium (Grade 2) as working material. The influence of the pulse frequency and energy, laser scanning speed and stepsize (spacing between adjacent passes) on the machined surface roughness is evaluated using Taguchi experimental design approach. The influence of process parameters on surface quality is investigated for two laser scanning strategies: hatching and crosshatching. The significant influence of the stepsize on the machined surface roughness was found

Experimental study of Nd:YAG laser machining of Cr-Ni austenitic stainless steel

Mikroobrada laserom je moćan postupak za stvaranje novih površina, konstrukcija, šupljina te složenih elektro-mehaničkih uređaja vrlo malih dimenzija pomoću laserskog zračenja. Taj postupak uveliko ovisi o pravilnom izboru i podešavanju parametara. U radu se opisuje eksperimentalno istraživanje laserske mikroobrade pomoću Nd:YAG lasera male snage i pobuđivanog diodom. U eksperimentu se koristio austenitski, Cr-Ni nerđajući čelik tipa X5CrNi18-10 (1 mm tanak metalni lim). Eksperiment je planiran pomoću Taguchi metode, a stvorene šupljine procijenjene konvencionalnim optičkim i također konfokalnim mikroskopom da bi se ustanovila površinska hrapavost i volumen odstranjenog materijala. Praktički je pokazano da se laserom male snage može skidati materijal s obradnog komada te je potvrđeno da je podešavanje ulaznih parametara od bitne važnost za ovaj postupak.Laser micromachining is a powerful process of creating new surfaces, structures, cavities and also complex electro-mechanical devices with very small dimensions by laser radiation. This process highly depends on choosing proper parameters and their settings. An experimental investigation of laser micromachining with low-power, diode-pumped Nd:YAG laser is presented in the paper. Material used in the experiment was austenitic, Cr-Ni stainless steel type X5CrNi18-10 (1 mm thin metal sheet). The experiment was planned by Taguchi method and the created cavities were evaluated by conventional optical and also confocal microscopy in order to state the surface roughness and the volume of removed material. It was demonstrated practically that low-power laser is able to remove material from workpiece, and it was confirmed that this process is crucially sensitive to input parameter settings

NANOSECOND YB FIBRE LASER MILLING OF ALLUMINIUM BRONZE: EFFECT OF PROCESS PARAMETERS ON THE SURFACE FINISH

In this study the relation between laser beam machining parameters and machined surface quality, applying nanosecond pulsed ytterbium fibre laser (wavelenght 1064 nm, maximal average output power 100 W) and aluminium bronze (AMPCO 25®) as working material, is experimentally studied. The laser micromilling was performed via the cross hatching milling strategy. The influence of the laser pulse intensity, scanning speed and laser track distance on the machined surface morphology formation and surface roughness parameters was evaluated using ANOVA (Analysis of Variance). Finally, the machining quality was evaluated by means of SEM micrographs. The results show that the laser pulse intensity played the most significant role on the final surface morphology formation. It was also documented only negligible influence of the laser track distance on the final surface roughness

Laser-Based Ablation of Titanium–Graphite Composite for Dental Application

Biocompatible materials with excellent mechanical properties as well as sophisticated surface morphology and chemistry are required to satisfy the requirements of modern dental implantology. In the study described in this article, an industrial-grade fibre nanosecond laser working at 1064 nm wavelength was used to micromachine a new type of a biocompatible material, Ti-graphite composite prepared by vacuum low-temperature extrusion of hydrogenated-dehydrogenated (HDH) titanium powder mixed with graphite flakes. The effect of the total laser energy delivered to the material per area on the machined surface morphology, roughness, surface element composition and phases transformations was investigated and evaluated by means of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), confocal laser-scanning microscopy (CLSM) and X-ray diffraction analysis (XRD). The findings illustrate that the amount of thermal energy put to the working material has a remarkable effect on the machined surface properties, which is discussed from the aspect of the contact properties of dental implants