Striation Zone Research Articles

Experimental study on the cutting performance of abrasive waterjet using steel slag as the particles

Abrasive waterjet (AWJ) is a promising method owing to the advantages of non-thermal effect and high removal rate. However, the high consumption of garnet abrasive has limited the development of AWJ technology. In this study, steel slag, which is a typical solid waste, was used as abrasive particles instead of garnet for abrasive waterjet (GAWJ) cutting for the first time. Stainless steel was used as specimen in the experiments to estimate the machining performance of steel slag abrasive waterjet (SAWJ). The results showed that SAWJ produced a cutting wear zone (CWZ) and a striation zone (SZ) on the cross-section surface compared to GAWJ. It produces longer SZ with dense and shallow striations on the surface compared to GAWJ. The influence of process parameters on the kerf produced by GAWJ and SAWJ is almost the same. SAWJ creates a finer kerf, contributing to higher cutting accuracy and less waste of substrate material. For material removal rate and roughness, performance similar to GAWJ can also be achieved. The SEM image reveals that micro cutting and plowing are the main material removal mechanisms for SAWJ cutting stainless steel. The cutting efficiency of SAWJ is about 90 % that of GAWJ, but the cutting efficiency per unit price can reach more than 260 %. The substitution of abrasives using steel slag is expected to bring about a 45 % reduction in operating expenses for the AWJ factories, potentially generating $8.34 million in annual savings for the Chinese AWJ industry.

Abrasive WaterJet Machining of Thick Carrara Marble: Cutting Performance vs. Profile, Lagging and WaterJet Angle Assessments

This paper deals with an assessment of the machined surface created by abrasive waterjet technology regarding its cutting performance versus profile, lagging and waterjet angle assessments. The results of the experiments presented in this study are with regard to Carrara marble. The machined surfaces were measured in seven different locations across a 40 mm depth of cut by a high precision contact-type profilometer and thus assessed using the standardized amplitude parameters of the profile distribution. The lagging and waterjet angle were also evaluated by creating a digital photo of the machined surface together with a reference gauge. The existence of machining marks on the machined surface has been mostly noticeable in the bottom zone around ~20 mm depth of cut down to jet exit. This investigation leads to a conclusion that, stand-off distance and traverse rate play the roles of the utmost importance in considerations of the machined surface quality in contrast to abrasive mass flow rate. In addition, while the striation zone (rough surface) cannot be eliminated entirely, by selecting proper process parameters, a smooth cutting machined surface can be accomplished.

Surface morphological features of fiber laser cutting of AA2219 aluminum alloy

High-power fiber laser cutting of AA2219 aluminum alloy was studied. The cutting surface morphologies were examined by optical stereoscopic microscope, and the characteristic sizes were measured by a Vernier caliper. The results showed that the cutting surface was grouped into three zones featured by different striation patterns from the upper to the bottom, which are horizontal striation zone at the upper, vertical striation zone at the middle, and oblique striation zone at the lower. The oblique striation zone was the roughest zone. An optimal range of laser line energy to get an accepted cutting surface both with a small fraction of oblique striation zone and less dross was found, which was determined as 25–35 J/mm. The formation mechanisms of surface features were summarized by the interaction between the gas flow inside the cut and the forces exerted on the molten pool.

Parameter design for cut surface characteristics in abrasive waterjet cutting of Al/SiC/Al2O3 composite using grey theory based RSM

The abrasive mixed waterjet was successfully employed to cut many materials including austenitic steel, inconel and glass for a variety of industrial applications. The present work focusses on studying the surface roughness, striation zone and striation angle in Abrasive waterjet cutting (AWJC) of Al/SiC/Al2O3 composite. The water pressure, traverse speed, abrasive flow rate and stand-off distance were included as the dominant parameters in the study. The features of striation zone (length and angle) and surface roughness were observed as the responses for each of the cutting trials planned as per Taguchi’s L18 orthogonal array. Parameter design was performed using the grey theory based response surface methodology (g-RSM) by following the method of simultaneous optimization to forecast the optimal cutting condition. All the studied parameters and their interactions were found to have a substantial effect on the observed responses. Significant improvements were observed in the responses obtained with the optimal parameter setting predicted by the g-RSM approach. The Atomic force microscopy (AFM) images and P-profile plots were also studied to observe the texture of the cut surface.

Effect of Process Parameters on Abrasive Contamination during Water Abrasive Jet Machining of Mild Steel

In the area of grit blasting, it is well known that microscopically small abrasive debris gets trapped on the surface, and due to impact the grits might cause the surface to fracture and a fraction of it to be embedded. The same problem appears in abrasive water jet (AWJ) machining especially in the so-called deformation wear zone or striation zone. The major aim in this study is to investigate the abrasive contamination on mild steel cutting surface. In the present study mild steel was used as the work material, since it is widely used in many industries. In order to analyze the pattern of the contaminations on the cut surface, the selected process parameters were abrasive flow rate, pressure and work feed rate. Abrasive contamination was measured at different depths along the path of the abrasives. The three selected zones for measuring abrasive contamination at different depths were the primary impact zone, the smoother zone and the deformation wear zone. It was found that contamination at the middle zone, i.e., the smoother zone had the least abrasive contamination while the initial impact zone and the deformation wear zone showed high abrasive contamination. It was also found that a higher pressure reduces abrasive contamination while a higher abrasive flow rate and work feed rate increase abrasive contamination.

Study on adhesion resistance behavior of sample with striated non-smooth surface by laser processing technique

Abstract Imitating the body surface morphology of some biological systems, several moulds with biomimetic surface were manufactured by laser processing technique. The key feature of this biomimetic surface is to arrange a various spacing of striations to create a non-smooth working surface. The anti-adhesion behavior of the samples with different surfaces was investigated. It was found that the biomimetic surface had a beneficial effect on improving the anti-adhesion behavior against polymers. Under the same conditions, the adhesion force of different non-smooth samples was 29.2–83.4% lower than that of smooth one, and it decreased with the increase in unit width or area ratio of the striations zone to the testing sample. In addition, physical or chemical structure of melting polymers was the key factor affecting the adhesion force of sample/polymer couples during ejecting the parts. Based on an in-depth study on the anti-adhesion mechanism of biomimetic surfaces by laser processing, the particular non-smooth structure of striation zone, which was proposed initially and indicated the greater tendency of forming apertures, was one of the main reasons for enhancing the adhesion resistance of moulds with biomimetic surface.

Thermal fatigue behavior of medium carbon steel with striated non-smooth surface

Imitating the body surface morphology of some biological systems, the medium carbon steel specimens with biomimetic surface were manufactured by laser processing technique. The key feature of this biomimetic surface is to arrange a various spacing of striations to create a non-smooth working surface. The thermal fatigue behavior of specimens with different surfaces, i.e. the specimen with 2-mm-spacing striations, 4-mm-spacing striations and smooth surface, was investigated and compared. It was found that the biomimetic surface has a beneficial effect on improving the thermal fatigue behavior of medium carbon steel, and that the specimen with 2-mm-spacing striations had the highest resistance to thermal fatigue. Compared with the base material, the striation zone on the non-smooth surface was mainly characterized by the refinement of grains and the alteration of microstructure. Based on such strengthening mechanism as well as the emergence of huge compressive residual stress in the striation zone, the pile–nail effect, which is proposed initially and can be explained by crack retardation mechanism together with stress counteraction mechanism, is the main reason for enhancing the thermal fatigue resistance of medium carbon steel with biomimetic surface.

Quantitative evaluation of abrasive contamination in ductile material during abrasive water jet machining and minimising with a nozzle head oscillation technique

In the area of grit blasting, it is well known that microscopically small abrasive debris gets trapped on the surface, and due to impact this grit might cause the surface to fracture and a fraction of it to embed. The same problem appears in abrasive aqua jet machining (AAJM), especially in the so-called deformation wear zone or striation zone. An experimental study was undertaken on a commonly used ductile material, aluminium Al–Mg4, 5Mn, which is used as a base material for manufacturing most of the aircraft/aerospace components. The results indicated that as the depth of cut increases the grit contamination decreases. A comparison was made between straight cutting and oscillation cutting, and it was observed that oscillation cutting is 10 times better than straight cutting for ductile material with respect to particle contamination. Alternative technology is suggested to overcome the grit contamination problem.

Quantitative evaluation of abrasive contamination in ductile material during abrasive water jet machining and minimising with a nozzle head oscillation technique

In the area of grit blasting, it is well known that microscopically small abrasive debris gets trapped on the surface, and due to impact this grit might cause the surface to fracture and a fraction of it to embed. The same problem appears in abrasive aqua jet machining (AAJM), especially in the so-called deformation wear zone or striation zone. An experimental study was undertaken on a commonly used ductile material, aluminium Al–Mg4, 5Mn, which is used as a base material for manufacturing most of the aircraft/aerospace components. The results indicated that as the depth of cut increases the grit contamination decreases. A comparison was made between straight cutting and oscillation cutting, and it was observed that oscillation cutting is 10 times better than straight cutting for ductile material with respect to particle contamination. Alternative technology is suggested to overcome the grit contamination problem.

The Ganoine Membrane of the Scales of Polypterus senegalus Includes a Labyrinth-Like Structure

The ganoine membrane is a basement membrane-like structure appearing between the maturation stage inner ganoine epithelium (IGE) and mineralized ganoine of polypterids and lepisosteids. In the present study, further ultrastructural investigation of the ganoine membrane of Polypterus senegalus was made and it was confirmed that it possessed a specialized labyrinth-like structure. The complete ganoine membrane was composed of six distinct zones: (1) a filamentous zone facing the distal plasmalemma of IGE, (2) lamella zone I, (3) vertical striation zone, (4) lamella zone II, (5) electron-dense zone, (6) electron-lucent zone directly facing the maturing ganoine surface. The ganoine membrane sometimes partially lacked some of these zones, but the electron-dense zone was usually present. Oblique or horizontal sections of the membrane showed that the vertical striation zone was made up of a typical labyrinth-like structure. Certain sulfated glycoconjugates were localized at the filamentous zone, especially adjacent to the lamella zone I and over the electron-dense zones.

Enhancing Abrasive Waterjet Cutting of Ceramics by Head Oscillation Techniques

Abrasive Water Jet (AWJ) cutting technology can provide very effective means for shape cutting of ceramics, but the slow cutting speed needs to be improved without compromising cutting quality. In this paper, experimental techniques based on statistical design principles and theoretical investigations were conducted to optimise and predict the AWJ cutting process applicable to ceramics. The new cutting head oscillation technique applied to the cutting process produced superior results and showed that the smooth zone depth increased by more than 30% with oscillation as compared to that without oscillation and both striation drag angle and frequency in the striation zone decreased.

Characteristics of Abrasive Waterjet Generated Surfaces and Effects of Cutting Parameters and Structure Vibration

We use three-dimensional surface topography analysis for evaluating waterjet generated surfaces. The waterjet generated surface is separated into smooth and striation zones, where striation influence is negligible in the smooth zone. It is found that the smooth zone has a random, moderately isotropic texture, with the height distribution nearly Gaussian. The effects of cutting speed, depth of cut, and abrasive size on the surface roughness are studied for the smooth zone and striation zone separately. This provides useful information for controlling process parameters to obtain smooth finished surfaces. Spectral analysis is used to investigate the surface striation and machine structure vibration. It is found that forced vibration of the mechanical structure strongly influences striations generated in the waterjet machining system.

Fatigue strength and fracture mechanism of ceramic-metal joints under cyclic bending

Abstract The cyclic fatigue strength and fracture mechanism of the ceramic-metal joint Si3N4-SS304 were investigated under cyclic bending loading. The results show that the fatigue strength at 107 cycles was about half the static bending strength. Different types of failure were observed for the low-cycle fatigue and high-cycle fatigue regions. Fracture surfaces were examined with SEM and EPMA. Three distinctive failure zones, including a fatigue striation zone, were clearly identified. The fatigue crack initiates and grows at the copper interlayer and finally kinks to the ceramic side. It is concluded that the copper interlayer dominates the fatigue strength of the joint.