Effect of Waterjet Machining Parameters on the Cut Quality of PP and PVC-U Materials Coated with Polyurethane and Acrylate Coatings

The article focuses on the machining of polymeric materials polypropylene (PP) and un-plasticized poly vinyl chloride (PVC-U) after surface treatment with polyurethane and acrylate coatings using waterjet technology. Two types of waterjet technologies, abrasive waterjet (AWJ) and waterjet without abrasive (WJ), were used. The kerf width and its taper angle, at the inlet and outlet of the waterjet from the workpiece, were evaluated. Significant differences between AWJ and WJ technology were found. WJ technology proved to be less effective due to the creation of a nonuniform cutting gap and significant burrs. AWJ technology was shown to be more efficient, i.e., more uniform cuts were achieved compared to WJ technology, especially at a cutting head traverse speed of 50 mm·min−1. The most uniform kerf width or taper angle was achieved for PP + MOBIHEL (0.09°). The materials (PP and PVC-U) with the POLURAN coating had higher values of the taper angle of the cutting gap than the material with the MOBIHEL coating at all cutting head traverse speeds. The SEM results showed that the inappropriate cutting head traverse speed and the associated WJ technology resulted in significant destruction of the material to be cut on the underside of the cut. Delamination of the POLURAN and MOBIHEL coatings from the base material PP and PVC-U was not demonstrated by SEM analysis over the range of cutting head traverse speeds, i.e., 50 to 1000 mm·min−1.

MULTI-RESPONSE OPTIMIZATION ON ABRASIVE WATERJET MACHINING OF GLASS FIBER REINFORCED PLASTICS USING TAGUCHI METHOD COUPLED WITH TOPSIS

This work aims to perform the multi-response optimization for abrasive waterjet machining (AWJM) of glass fiber reinforced plastics (GFRP). The experiments were conducted with AWJM factors like pressure (P), traverse speed (TS), and standoff distance (SOD) at three levels. Taguchi’s L9 orthogonal array (OA) was used to design the experiments. The influence of control factors was evaluated by measuring the surface roughness and taper angle while cutting GFRP. The optimum parameter for an individual response was obtained through Taguchi’s [Formula: see text]/[Formula: see text] and multi-response optimization was performed with TOPSIS. From TOPSIS, the optimal parameter of the pressure of 200 MPa, standoff distance (SOD) of 1.5[Formula: see text]mm, and traverse speed (TS) of 25[Formula: see text]mm/min were found. After optimization, the taper angle was decreased by 1.41%. The influence of cutting variables on the responses was statistically analyzed through analysis of variance. It was observed that the pressure has a significant effect on multi-response characteristics and a contribution of 85.90%. After, AWJM, the surface was examined using SEM analysis and found the deformation and pull-out of fibers.

Experimental Analysis of Kerf Taper Angle in Cutting Process of Sugar Palm Fiber Reinforced Unsaturated Polyester Composites with Laser Beam and Abrasive Water jet Cutting Technologies

In this research, the effect of processing input parameters on the kerf taper angle response of three various material thicknesses of sugar palm fiber reinforced unsaturated polyester composite was investigated as an output parameter from abrasive waterjet and laser beam cutting techniques. The main purpose of the study is to obtain data that includes the optimum input parameters in cutting the composite utilizing these two unconventional techniques to avoid some defects that arise when using traditional cutting methods for cutting the composites, and then make a comparison to determine which is the most appropriate technique regarding the kerf taper angle response that is desired to be reduced. In the laser beam cutting process, traverse speed, laser power, and assist gas pressure were selected as the variable input parameters to optimize the kerf taper angle. While the water pressure, traverse speed, and stand-off-distance were the input variable parameters in the case of waterjet cutting process, with fixing of all the other input parameters in both cutting techniques. The levels of the input parameters that provide the optimal response of the kerf taper angle were determined using Taguchi’s approach, and the significance of input parameters was determined by computing the max–min variance of the average of the signal to-noise ratio (S/N) for each parameter. The contribution of each input processing parameter to the effects on kerf taper angle was determined using analysis of variation (ANOVA). Compared with the results that were extrapolated in the previous studies, both processes achieved acceptable results in terms of the response of the kerf taper angle, noting that the average values produced from the laser cutting process are much lower than those resulting from the waterjet cutting process, which gives an advantage to the laser cutting technique.

Optimization of the taper angle of the jetter confuser used for reversible blast cleaning of propellers from corrosion

It is shown that it is very effective to remove corrosion products from various surfaces, including the metal surface of the propeller, using the new technology of reverse-jet cleaning (RJC) developed by the authors. The RJS technology is based on the physical principle that the jet of the working fluid (pulp based on river sand or bentonite clay), upon impact with the surface to be cleaned, turns 180°, which leads to an increase in the jet effect on the surface to be cleaned by 1.5–2 times due to the occurrence of the reactive component. To ensure the marked turn of the jet, an original design of the body was developed, which is distinguished by a patent novelty. One of the main elements in this design is a jet-forming device in the form of a confuser. The presented theoretical studies of the pressure loss of the working fluid in the confuser channel, based on the study of the pressure loss function to the extremum, which made it possible to obtain a dependence for calculating the optimal taper angle in a wide range of Reynolds numbers characterizing the turbulent mode of motion taking into account the influence of the working fluid density and its dynamic viscosity, the average speed of movement of the working fluid, the radius of the confuser, as well as the coefficient of equivalent roughness, i.e. from gradual wear of the confuser channel. The resulting dependence can be recommended for calculation in the design of jet cleaning devices and other installations of jet technology.

Femtosecond Laser Engraving of Deep Patterns in Steel and Sapphire

Femtosecond laser engraving offers appealing advantages compared to regular laser engraving such as higher precision and versatility. In particular, the inscription of deep patterns exhibits an increasing interest in industry. In this work, an optimization protocol based on constraining overlap ratio and scan number is demonstrated. The proposed method allows changing overlap ratio while maintaining depth in the same range, which reduces the sampling number. This study WAS applied to stainless steel 316 L and sapphire for engravings deeper than 100 μm. Results exhibit overall depths higher than threshold values and allowed to determine optimized engraving quality, for instance, roughness in steel can be reduced while maintaining depth and taper angle by reducing overlap ratio. The optimized laser parameters such as roughness and taper angle factors for sapphire were also found to be as follows: 200 kHz, 86% overlap and 12 J/cm2. As a demonstration, a logo engraving is illustrated at the end.

Multipolar-sensitive engineering of magnetic dipole spontaneous emission with a dielectric nanoresonator antenna

We propose an axisymmetric silicon nanoresonator with designed tapered angle well for the extraordinary enhancement of the decay rate of magnetic dipole (MD) emitters. Due to the resonant coupling of a MD emitter and the MD mode of the subwavelength resonator, the Purcell factor (PF) can easily reach 500, which is significantly higher than the PF when using a silicon nanosphere of the same size. The PF and the resonance frequency are conveniently tuned through the resonator diameter and the taper angle of the blind hole. When supported by a metallic substrate, further enhancement ($$>10^3$$ > 10 3 ) of the MD spontaneous emission is triggered by an image-induced quadrupolar high-Q mode of the nanoantenna. For the sake of comparison we include a critical analysis of the canonical problem that considers a Si spherical shell. Our results might facilitate a novel strategy for promising realizations of chip-scale nanophotonic applications.

Spindle assembly with adjustable output characteristics

A method for controlling the output characteristics of spindle assemblies based on the use of tapered gas bearings with a small taper angle is proposed. An experimental bench for studying the performance characteristics of these bearings is described. The results of researches of gas-static bearings with a small taper angle are presented. Keywords: spindle assembly, gas-static support, small taper angle, experiment. [email protected]

Impacts of Traverse Speed and Material Thickness on Abrasive Waterjet Contour Cutting of Austenitic Stainless Steel AISI 304L

Abrasive water jet machining is a proficient alternative for cutting difficult-to-machine materials with complex geometries, such as austenitic stainless steel 304L (AISI304L). However, due to differences in machining responses for varied material conditions, the abrasive waterjet machining experiences challenges including kerf geometric inaccuracy and low material removal rate. In this study, an abrasive waterjet machining is employed to perform contour cutting of different profiles to investigate the impacts of traverse speed and material thickness in achieving lower kerf taper angle and higher material removal rate. Based on experimental investigation, a trend of decreasing the level of traverse speed and material thickness that results in minimum kerf taper angle values of 0.825° for machining curvature profile and 0.916° for line profiles has been observed. In addition, higher traverse speed and material thickness achieved higher material removal rate in cutting different curvature radii and lengths in line profiles with obtained values of 769.50 mm3/min and 751.5 mm3/min, accordingly. The analysis of variance revealed that material thickness had a significant impact on kerf taper angle and material removal rate, contributing within the range of 69–91% and 62–69%, respectively. In contrast, traverse speed was the least factor measuring within the range of 5–18% for kerf taper angle and 27–36% for material removal rate.