Dominika Lehocká

Sandstone Turning by Abrasive Waterjet

The machining of materials with specific mechanical properties causes problems in terms of the required quality, economic efficiency, and overall effectiveness of the process. A number of works have been published which indicate that the subjects of interest are still important (Krolczyk et al. 2013). The machining of the aforementioned materials based on conventional methods does not always meet the requirements of eco-friendly technology nor the efficiency potential of the technological device and tool (Vasilko and Strojný 1967; Krolczyk et al. 2014). The abrasive waterjet (AWJ) represents a suitable technological method that has specific benefits resulting from the nature of the tool. Many scientific reports have been written about using the water jet and the AWJ for cutting (Summers 1972; Ciccu and Grosso 2014), drilling (Teale 1965), turning (Sitek 2009; Sitek 2005, 2011), and for the purposes of underground mining (Summers 1992; Sharma et al. 2011). The AWJ can be used for the creation of rotating symmetric parts from rocks by turning. The production of parts using standard methods is very complicated and even impossible for some rock materials due to their properties (Summers 1972; Agus et al. 1993; Aydin et al. 2013). The use of the AWJ is an option for how to eliminate problems related to the standard method of turning (Sitek et al. 2005). The first results were published by Dr. Hashish (1987) 28 years ago. Ansari and his colleagues (1992) undertook relatively extensive research into turning visualizations using a high-speed camera. Hlavac and Palicka (2006) applied this method for the turning of many materials used in industry. Axinte et al. (2009) applied this method for the turning of grinding wheels. Interesting results were obtained in glass turning (Zhong and Han 2002), alumina ceramic turning (Liu et al. 2014), and the turning of hard-strength materials (Sitek 2009). The application of this turning method enables the machine rotating of semifinished products of varying structures and shapes (Henning 1999).

Assessment of Deformation Characteristics on CW004A Copper Influenced by Acoustically Enhanced Water Jet

Paper deals with copper CW004A deformation characteristics evaluation after pulsating water jet disintegration. Experimental samples were prepared from copper CW004A with marking A, B, and C. As variable factors were selected combinations of pressure of pump pressure and nozzle diameter: A (p = 65 MPa; d = 1.067 mm), B (p = 49 MPa; d = 1.321 mm), C (p = 38 MPa; d = 1.600 mm). Surface topography was evaluated using optical profilometry. Microhardness measurement was measured using Vickers indenter. Hardness measurement was performed on seventeen points under disintegrated area in distance from 0.1 to 3 mm. Measured values indicate slight increase of strain hardening undercutting area.

Surface Roughness of Graphite and Aluminium Alloy After Hydro-abrasive Machining

The paper compares the quality of machined surface of graphite and aluminium alloy by abrasive waterjet using the focusing tube with a diameter of d f1 = 0.5 mm and d f2 = 0.78 mm. The machining was carried out using the technology of rotating workpiece disintegration by abrasive waterjet. Abrasive tangential waterjet was used to carry out the experiment (water pressure P = 400 MPa). Workpieces were clamped in the rotating chucking appliance with rotation frequency n = 300 min−1. The change in focusing tube diameter caused the change in values of roughness parameters and also caused the change of resulting shape of workpieces. Values of roughness parameters were measured using the MicroProf FRT optic profilometer.

Evaluation of Possibility of AISI 304 Stainless Steel Mechanical Surface Treatment with Ultrasonically Enhanced Pulsating Water Jet

Experimental study described in this article is focused on evaluation of dynamic effect of PWJ on disintegration efficiency on AISI 304 stainless steel surface. AISI304 stainless steel was disintegrated with circular nozzle diameter 1.19 mm, pressure 70 MPa, frequency 20.25 kHz and traverse speed 100 mm.s−1 (202 impacts per millimeter). Disintegration efficiency was evaluated based on surface and subsurface characteristics. Surface characteristics were evaluated based on surface topography and roughness parameters Ra [μm], Rz [μm], Rp [μm] and Rv [μm] comparison of disintegrated and non-affected area. Subsurface changes in material structure were described based on metallographic analysis and hardness measurement HV0.2 under the eroded area. The results of the disintegration efficiency evaluation of AISI 304 stainless steel surface show that was no massive erosion of material. Surface quality was slightly changed. Small microscopic craters were predominantly created on surface. Craters were characterized with predominant pitting mechanism and prevails fracture mechanism of material removal.

Rationalization of material flow in production of semitrailer frame for automotive industry

Osnovna ideja rada je prikaz toka vrijednosti uz identifikaciju izvora troskova i nedostataka, koji ce pomoci da se razotkriju skrivene pricuve u proizvodnji. Analiza obuhvaca postojece stanje u pojedinacnim postupcima na proizvodnoj traci. Nakon prepoznavanja postojecih nedostataka napravljen je plan racionalizacije u kojemu je rabljena kombinacija elemenata lean proizvodnje. Predložena bi se rjesenja mogla primijeniti kad se primijene principi lean proizvodnje na pojedinim dijelovima montažne trake u cijelom pogonu. U slucaju da se predloženo rjesenje ne može primijeniti u praksi može se koristiti kao model za druge vrste poboljsanja kao sto su smanjenje otpada i nedostataka.

The Simulation as a Tool for Technical Devices Design and Optimization

The article deals with the research of the pressures originated inside the cooling system and also in the mould cavity during the injection moulding process. The simulations were realized for three designed types of running system and for four versions of cooling system. 3D model of the mould was created in Autodesk Inventor Proffesional software and then solidification of material was simulated in Autodesk Moldflow Insight software. The results were compared and the best version from the view of pressure was manufactured and placed into the injection moulding machine Arburg Allrounder 320 C.