Experimental analysis of surface roughness and surface texture of machined and fused deposition modelled parts

Cilj istraživanja bio je utvrditi integritet površine dijelova proizvedenih klasičnim postupkom obrade odvajanjem čestica, tokarenjem i aditivnim postupkom taložnog očvršćivanja (tzv. FDM postupak). Pri analizi površine korištene su suvremene metrološke metode auto korelacije i gradijentne razdiobe. Površinska tekstura analizirana je pomoću Infinite Focus Measurement Machine (IFM) uređaja. Studija je provedena u stvarnom proizvodnom pogonu tijekom prototipne izrade novih proizvoda.The objective of the investigation was to identify surface integrity of machined parts by turning and by Fused Deposition Modelling (FDM) additive method produced ones. Surface analysis was made by using novel metrology methods: auto correlation and gradient distribution. An Infinite Focus Measurement Machine (IFM) was used for the surface texture analysis. The study was performed within a production facility during the prototyping process of new products

Investigations Into Surface Integrity in the Turning Process of Duplex Stainless Steel

The objective of the investigation was to identify surface roughness and surface topography parameters after the turning of Duplex Stainless Steel (DSS) with wedges of coated sintered carbide. The auto correlation and gradient distributions for variable cutting parameters were compared. An Infinite Focus Measurement Machine (IFM) was used for the surface texture analysis. The study was performed within a production facility during the machining of electric motor parts and deep-well pumps

Evaluation of hoop residual stress variations in the thickness of dissimilar welded pipes by using the LCR ultrasonic waves

Mjerenje naprezanja pomoću ultrazvučnih valova temelji se na akustičnoelastičnom zakonu, t.j.odnosu između naprezanja i brzine valova u inženjerskim materijalima. Uzdužni kritički lomljen - Longitudinal critically refracted (LCR) val je popularni ultrazvučni val u primjeni ultrazvučnog mjerenja naprezanja. LCR val je masovni uzdužni val koji putuje na efektivnoj dubini ispod površine. U ovom radu procjenjuje se varijacija cirkularnog zaostalog naprezanja u debljini cijevi. Cijev je proizvedena zavarivanjem dviju različitih cijevi od nehrđajućeg čelika AISI 304 i ugljičnog čelika tipa A106-B. Varijacije zaostalih naprezanja u debljini cijevi mjere se pomoću četiri različite frekvencije pretvarača, dok su nominalne frekvencije 1 MHz, 2 MHz, 4 MHz i 5 MHz. Uporabom različitih frekvencija omogućeno je LCR valovima da prodru do različitih dubina i mjere veličinu naprezanja cijevi. Pokazalo se da se razlika u naprezanju između unutarnje i vanjske površine cijevi i također između strane cijevi od nehrđajućeg čelika i one od ugljičnog čelika može procijeniti pomoću LCR valova.Stress measurement by using ultrasonic waves is based on acoustoelasticity law, i. e. the relation between stress and wave velocity in engineering materials. Longitudinal critically refracted (LCR) wave is a popular ultrasonic wave in the ultrasonic stress measurement application. The LCR wave is a bulk longitudinal wave that travels within an effective depth underneath the surface. This paper evaluates hoop residual stress variation in the thickness of a pipe. The pipe is manufactured by welding two dissimilar pipes from AISI stainless steel 304 and carbon steel A106-B type. The residual stresses variations in the thickness of pipe are measured by using four different frequencies of transducers while the nominal frequencies are 1 MHz, 2 MHz, 4 MHz and 5 MHz. Using different frequencies enables the LCR waves to penetrate in different depths and measure the bulk stresses of pipe. It has been shown that the stress difference between inner and outer surfaces of pipes and also between the stainless steel and carbon steel side of dissimilar pipe can be evaluated by using the LCR waves

Study of the surface integrity microhardness of austenitic stainless steel after turning

Cilj je istraživanja bio odrediti mikrotvrdoću integriteta površine (SI) austenitnog nehrđajućeg čelika nakon tokarenja vrhom alata obloženog karbidom. Integritet površine je važan kod određivanja otpornosti koroziji kao i pojave pukotine kod zamora materijala. Istraživanje je obuhvatilo analizu mikrotvrdoće SI za različite parametre rezanja u postupku suhog tokarenja austenitnog nehrđajućeg čelika 1.4541. Pokazalo se da povećanje brzine rezanja dovodi do povećanja dubine kaljenja SI. Analiza je provedena u proizvodnoj hali tijekom proizvodnje dijelova električnog motora i dubinskih pumpi.The objective of the investigation was to determine the surface integrity (SI) microhardness of austenitic stainless steel after turning with coated carbide tool point. Surface integrity is important in determining corrosion resistance, and also in fatigue crack initiation. The investigation included analysis of microhardness of SI for different cutting parameters in dry turning process of 1.4541 austenitic stainless steel. It has been shown that increase of cutting speed leads to the increase of SI hardening depth. The study has been performed within a production facility during the production of electric motor parts and deep-well pumps

Strengthening Effect after Disintegration of Stainless Steel Using Pulsating Water Jet

The article deals with the measurement of micro-hardness of the track by the action of ultrasonic excitation of pulsating water jet. The cumulative effect of liquid matter in the form of droplets concentrated in waveform measurements was provided in horizontal and vertical direction to material core (AISI 304). The material was subjected to pressures of p = 40, 50 and 60 MPa with the actuator working at a frequency of 20,14 kHz and traverse speed v = 1,1 mm/s, v = 0,80 mm/s and v = 0,30 mm/s respectively. The micro hardness measurement was carried out after machining it by pulsating water jet. The values were recorded in the zone located transversally under the trace to the depth of 1,5 mm with 0,1 mm distance between successive points. It was found that the deformation of material was ascertained from the boundary to the outer environment created by pulsating water jet to the inner core of the material. The results indicate that the pressure was the most influential parameter, which was responsible for the deformation strengthening of the material

Thermaltransport phenomenon of submerged arc welding process

U ovom je radu opisan prijelaz topline razmatrajući toplinsko zračenje izvora topline ovalnog oblika i prijenos topline rastaljene pokretne elektrode. Analitičkom se temperaturnom polju približilo ravnim segmentima za ovalni izvor topline s putanjom uzimajući u obzir promjene temperature uzrokovane sljedećim prijelazima (porast temperature zbog izvora topline i rastaljene pokretne elektrode i automatski hlađena područja ranije zagrijana). Točnost rješenja je provjerena usporedbom s eksperimentalnim rezultatima.In present work, thermal transport considering heat radiation by oval heat source shape and heat transfer of molten moving electrode was presented. In present paper, an analytical solution was presented by aggregating temperature increments caused by applying liquid metal and heat radiation of moving electrode. The assumptions for the study were heat source of temperature of applied metal in oval shape and Gaussian distribution of electric heat source. Accuracy of the solution was verified comparing experimental results

Measurement of thermal emission during cutting of materials using abrasive water jet

This article deals with measurement of the thermal gradient on material during abrasive water jet cutting. The temperature was measured by thermocamera before the technological process started, during the abrasive water jet cutting process technology, and just after the cutting process. We performed measurements on several types of materials. We calculated the approximate amount of energy during the abrasive water jet cutting process technology that changes into thermoenergy, which is the current water pressure drained in a catcher tank

Microscopic characteristics of magnetorheological fluids subjected to magnetic fields

© 2020 Elsevier B.V. With the aim of studying the microscopic characteristics of a magnetorheological fluid (MRF) in a magnetic field, the theoretical analyses of the particles dynamics in a magnetic field are presented, and a model for the particle motion is proposed. Based on these analyses, a three-dimensional numerical simulation of the microstructure of MRFs in different magnetic fields is performed. Furthermore, the microstructures of the MRFs are investigated using industrial computed tomography (CT) imaging. The numerical simulation and industrial CT results indicate that the chain structure of the same MRF becomes more apparent as the magnetic field strength increases, and in the same external magnetic field, this chain structure also becomes more apparent with an increase in the particle volume fraction. The lengths of particle chains in different magnetic fields are also captured in the industrial CT experiments. When the magnetic field strength is 12 mT, the particle chains of the MRF with a particle volume fraction of 30% reach more than 10 mm in length, which bridge the inner diameter of the container, and the dense clusters-like structure is formed, the clusters-like structure becomes denser with an increase in magnetic field. Moreover, the particle chain lengths of MRF with high particle volume fractions increase sharply with the magnetic field. The experiments demonstrated that the industrial CT is an efficient method to study the microstructures of MRFs by providing particle distributions of MRFs more clearly and intuitively