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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 Ep 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 μm. The indentation was carried in three series of 10 indents with 100 μm 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.

Printed circuit boards are part of electronic devices and affect the functioning of today's society. At present, printed circuit boards are manufactured for relatively long periods of time using the same methods. The presented article focuses on the design of the possibility which eliminates errors arising from the development and etching of PCBs. It describes the theoretical design of the use of hydrodynamic continuous water jet machining in PCB production. The proposal points to the possibility of using positive water jet properties are as such: no heat-affected zone, thin separation gap, absence of dust particles and toxic fumes.

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 70 MPa, circular nozzle diameter was 1.19 mm, traverse speed of cutting head was 100 mm s−1 (which is 200 impact for millimeter) for stainless steel and 660 mm s−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 μm. 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 μm deep), it is possible to assume the material plastic deformation, but the value of aluminum alloy tensile strength Rm is not exceeded. The experimental results from an aluminum alloy evaluation do not confirm the subsurface mechanical strengthening of the material.

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.