Racionalizacija toka materijala u proizvodnji polu-okvira za automobilsku industriju

The core idea of the paper is a value stream mapping with identification of waste sources, and drawbacks which help to uncover hidden reserves of production. The analysis covers the current state of individual processes within the production line. After determination of the present drawbacks the plan of rationalization was created in which the combination of elements of lean production was used. The proposed solutions could be used when establishing the principles of lean production at particular sections of the assembly line within the whole plant. In case that proposed solution cannot be put into practice it can be used as a blueprint for other types of improvement respectively decreasing of waste and drawbacks.Osnovna ideja rada je prikaz toka vrijednosti uz identifikaciju izvora troškova i nedostataka, koji će pomoći da se razotkriju skrivene pričuve u proizvodnji. Analiza obuhvaća postojeće stanje u pojedinačnim postupcima na proizvodnoj traci. Nakon prepoznavanja postojećih nedostataka napravljen je plan racionalizacije u kojemu je rabljena kombinacija elemenata lean proizvodnje. Predložena bi se rješenja mogla primijeniti kad se primijene principi lean proizvodnje na pojedinim dijelovima montažne trake u cijelom pogonu. U slučaju da se predloženo rješenje ne može primijeniti u praksi može se koristiti kao model za druge vrste poboljšanja kao što su smanjenje otpada i nedostataka.Web of Science2341220121

Surface Integrity Evaluation of Brass CW614N after Impact of Acoustically Excited Pulsating Water Jet

AbstractPresented article is focused on surface integrity evaluation of brass CW614N form the sight of surface topography, structural changes in surface layers and strengthening character in subsurface layers after impact of acoustically excited pulsating water jet (PWJ). Surface topography was evaluated using optical profilometry. Structural changes in subsurface layer were observed based on mass material removal Δm [mg/s] and maximal depth of penetrance of PWJ hmax [mm]. Nano indentation measurement according to Berkovich were used to examination of strengthening character in subsurface layer. Disintegration of experimental samples was performed under constant technological conditions: hydraulic power of plunger pump Ph = 19kW; round nozzle diameter d = 1.6mm; feed speed rate v = 0.75mm/s; pressure of plunger pump p = 38MPa, stand-off distance of nozzle from target material z = 45mm; ultrasound frequency f = 20.29kHz and as variable factor was set power of ultrasound P on values 340, 360 and 380W. In terms of surface topography experimental investigation proved that PWJ under selected conditions is not suitable for precision machining. Evaluation of the surface characteristics indicates that the chemical composition has a significant effect on material weight loss Δm [mg/s] and a maximum depth of penetration of PWJ hmax [mm]. Evaluation of characteristics of subsurface layer was observed strengthened area with lower elasticity

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

The Virtuosity of Violoncello Playing in the Work of David Popper

Hlavním cílem této práce bylo představit osobnost Davida Poppera jako virtuóza, pedagoga a skladatele. Jeho virtuózní technika dala základ k moderní violoncellové hře. Upozorňuji zvláště na jeho Vasokou školu violoncellové hry a na jeho ostatní virtuozní skladby

The Virtuosity of Violoncello Playing in the Work of David Popper

The main aim of my work is to introduce the personality of David Popper, as a virtuous cellist, teacher and composer.His virtuous technique gave the ground to modern cello playing. I pay a special attention to his etudes high School of Violoncello Playing and to his concertant pieces

Dynamic simulation for optimisation solution of manufacturing processes

One way how to study the real behaviour of industrial processes or systems in practice is to use computer simulations. We can simulate different conditions and find optimal parameters without increased risk. The right application of these parameters in practice can produce the desired results. The advantage is not only the safe verification of various variants of the simulated parameters, but also the possibility of their use in different areas of industrial practice. This article deals with an example of the use of simulation in the production of the selected automobile cooling system component. The simulation model was created to design the correct number of Kanban circuits to shorten production lead time and to reduce inter-operational supplies. The suitability of using computer simulations to optimize the production processes and systems in practice can be confirmed based on comparison of the results from the computer simulation with results achieved in practice

Dynamic simulation for optimisation solution of manufacturing processes

One way how to study the real behaviour of industrial processes or systems in practice is to use computer simulations. We can simulate different conditions and find optimal parameters without increased risk. The right application of these parameters in practice can produce the desired results. The advantage is not only the safe verification of various variants of the simulated parameters, but also the possibility of their use in different areas of industrial practice. This article deals with an example of the use of simulation in the production of the selected automobile cooling system component. The simulation model was created to design the correct number of Kanban circuits to shorten production lead time and to reduce inter-operational supplies. The suitability of using computer simulations to optimize the production processes and systems in practice can be confirmed based on comparison of the results from the computer simulation with results achieved in practice

Effect of pulsating water jet disintegration on hardness and elasticity modulus of austenitic stainless steel AISI 304L

The presented article is focused on the evaluation of mechanical properties of stainless steel disintegrated using an ultrasonically modulated pulsating water jet. The experimental procedure was performed using a nozzle with a circular orifice with an equivalent diameter of 1.6 mm. The mechanical properties evaluation was based on indentation elasticity modulus E-p and nano hardness H, which were measured using nanoindentation technique. Influence of ultrasonic power and plunger pressure change on disintegrated material was evaluated. Changes in mechanical properties in dependence on distance from the disintegrated surface were evaluated. Elasticity modulus and nano hardness change were observed below and on the sides of the disintegrated surfaces. Measurements were performed until the distance of 930 mu m. The indentation was carried in three series of 10 indents with 100 mu m spacing located below the affected area, next to the affected area and in the unaffected material. Results of experimental testing show changes of nano hardness (generally an appreciable decrease) and elasticity modulus (limited increase) of material under and to the side of the newly created surface.Web of Science1075-62730271

Comparison of ultrasonically enhanced pulsating water jet erosion efficiency on mechanical surface treatment on the surface of aluminum alloy and stainless steel

Presented article is focused on the comparison of erosion efficiency on the surface treatment of ultrasonically enhanced PWJ (pulsating water jet) on different metal materials surfaces. Surfaces of EN X5CrNi18-10 stainless steel and EN-AW 6060 aluminum alloy were evaluated. Pulsating water jet technological factors were set to the following values: pressure was 70MPa, circular nozzle diameter was 1.19mm, traverse speed of cutting head was 100mms(-1) (which is 200 impact for millimeter) for stainless steel and 660mms(-1) (which is 30 impact per millimeter) for aluminum alloy. The evaluation was made based on the surface topography evaluation, evaluation of microstructure, and microhardness in the transverse cut. The results of the stainless steel surface evaluation show slight erosion of material, with creating microscopic craters. Subsurface deformation was found to a depth of a maximum of 200 mu m. Hardness measurement shows 11% higher value of hardness under the affected area compared with a measurement in the center of the sample. From the findings, subsurface deformation strengthening of stainless steel with minimal influence of material surface can be assumed. Surface deformation of aluminum alloy is characterized by the formation of more pronounced depressions and less pronounced protrusions. Depressions were created by a combination of compression and tearing off material parts. A decrease in hardness value of 18% compared with a measurement in the center of the sample. In places of the first indent just below the disintegrated area (up to 600 mu m deep), it is possible to assume the material plastic deformation, but the value of aluminum alloy tensile strength R-m is not exceeded. The experimental results from an aluminum alloy evaluation do not confirm the subsurface mechanical strengthening of the material.Web of Science1035-81656164

Pulsating water jet erosion effect on a brass flat solid surface

The present study is focused on the disintegration effect of ultrasound-enhanced pulsating water jet (PWJ) technology on brass CW614N. The first part of the study discusses the effect of a combination of factors based on the full factorial design of experiments (DoE) 3(3). Traverse speed v (mm s(-1)), circular nozzle orifice diameter d (mm), and hydraulic power P (h) (kW) are selected as the disintegration variable factors. Mass material removal Delta m (mg s(-1)) is evaluated based on the change in these variable factors. In the next part, a verification experiment is performed with by varying the traverse speed between 0.2 and 1.4 mm s(-1). The mathematical model calculated in DoE is confirmed. Moreover, the significant effect of hydraulic power P (h) (kW) on the efficiency of the PWJ disintegration is demonstrated. The last part of the study discusses the surface and subsurface effects on a PWJ after brass CW614A erosion. A sample disintegration with hydraulic power P (h) = 13 kW and circular nozzle diameter d = 1.321 mm is observed. Optical profilometry and scanning electron microscopy are performed to visualise the surface erosion of a selected groove. A significant mass material removal is observed from the groove surface, and the disintegrated surface is characterised by erosion and crater formation. A slight cold deformation with a maximum depth of 200 mu m is detected in the subsurface layer. The experiment and results present a part of an extensive research focused on describing the PWJ disintegration efficiency for metallic materials.Web of Science971-41112109