Carbon dioxide (CO2) laser cutting finds one of its most relevant applications in the processing of a wide variety of polymeric materials like thermoplastics and thermosetting plastics. Different ...types of polymeric materials like polypropylene (PP), polymethyl methacrylate (PMMA), low- and high-density polyethylene (LDPE, HDPE), are processed by laser for different household as well as commercial products in the industry. The reason is their easy availability and economical aspect in the market. The problems associated with laser cutting include heat-affected zone (HAZ) generated on the cut surface, kerf width (KW), surface roughness (SR), dross formation, and striations formation. Furthermore, other related problems include taper cutting for deep parts and high-power consumption. The primary purpose of this work is a comprehensive literature review in CO2 laser cutting of polymeric materials. The influence of parametric variation on the cut quality is also explained. Cut quality in terms of KW, SR, HAZ, dross formation, and striations formation is analyzed by optimizing cutting variables like laser power (PL), cutting speed (CS), assist gas pressure (Pg), pulse frequency, nozzle type and its diameter, and stand-off distance (SOD). The effects of the laser cutting on the properties of different thermoplastics/thermosetting materials are also reported. However, this topic requires further studies on exploring the range of polymeric materials, and their optimal parameters selection to improve the cut quality. Therefore, the research gaps and future research directions are also highlighted in the context of CO2 laser cutting for polymeric materials.
•In this research, 2D triangular anti-trichiral structure and auxetic stents with the aims of uniform shrinkage behavior and high energy absorption were introduced.•Under compression, the deformation ...mechanisms were based on the rotation of the triangles and bending of the ligaments.•In the 2D structures, the most negative Poisson's ratio values, with the values of υyz = −0.55 and υzy = −1.6, were measured in the structure in which the triangle edge lengths were considered 13 mm.•In the cylindrical stents, the most negative Poisson's ratio values, with the values of υzx = −2.2 and υzy = −2.19, and uniform shrinkage behavior were observed in the stent in which the triangle edge lengths were considered 15 mm.•The energy absorption capability in the triangular anti-trichiral stent was three times as high as the conventional anti-trichiral stent.•The lateral displacements of the triangular anti-trichiral stent, under compression, were twice as high as the conventional anti-trichiral stent.
In this study, 2D triangular anti-trichiral structures and auxetic stents, under compression, were introduced. The cores of the anti-trichiral structures were the equilateral triangles. The deformation mechanisms in 2D structures were based on the rotation of the triangles and bending of the ligaments. A parametric study was carried out to investigate the dependence of the Poisson's ratio to the triangle edge lengths. The most auxeticity, with the values of υyz = −0.55 and υzy = −1.6, was obtained in the structure in which the triangle edge lengths were considered 13 mm. Next, the auxetic stents with the aims of uniform shrinkage behaviors as well as high energy absorption were introduced. For this purpose, the equilateral triangles were distributed on the cylindrical surfaces along with the peripheral and longitudinal directions. Under compression, the stent with 15mm triangle edge lengths possessed uniform shrinkage behavior, and the values of Poisson's ratio were measured υzx = −2.2 and υzy = −2.19. Finally, the comparisons between triangular and conventional anti-trichiral stents were performed. It was observed that the lateral displacements, as well as energy absorption of the triangular stents were twice and three times as high as the conventional anti-trichiral stents respectively.
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•The mechanical properties of CFRP short pulse laser cutting and the effect of damage on it were studied.•Combined with mechanical drilling, the crack propagation and fracture mode of CFRP laser ...cutting scale are analyzed.•Large damage further reduces the tensile and bending strength of CFRP and intensifies the fatigue crack propagation.•The findings are helpful to lay a foundation for damage suppression and improvement of CFRP mechanical properties.
Carbon fiber reinforced polymer (CFRP) composites are widely used in the aerospace field because of their outstanding performance. Short pulse laser is an effective means for efficient and high-quality cutting of CFRP. However, the inevitable thermal effect of laser processing results in damage such as heat-affected zone, and the exposed area of fiber loses the ability to transmit force, which weakens the mechanical properties of CFRP. However, the effect of thermal damage on mechanical properties is complex. In this paper, the dynamic and static mechanical behavior of short pulse laser cutting CFRP is studied, and the effect of cutting damage on the mechanical properties is explored. The mechanical properties of CFRP plate hole laser cutting is similar to those of mechanical drilling but are lower than those of material without hole due to the existence of holes. Matrix cracking exists in the tensile fatigue of laser cutting holes, while surface cracks occur in the stress-concentrated area due to the not smooth cutting edge of mechanical drilling. Compared with small laser cutting damage, the tensile and bending strength of the CFRP plate were weakened by 11.5% and 6.2%, respectively. The tensile fatigue crack propagation and fiber protrusion are aggravated by large damage. The damage always starts at both sides of the vertical direction of the hole under 0° laying, resulting in cracks along the fiber axis until fracture. The failure mode and fracture cross-section morphology are mainly fiber tears and delamination, and the section of the 90° laying specimen surface is tidier than that of the 0° laying specimen. The mechanical properties under thermal damage studied in this paper will help to lay a foundation for damage suppression and improvement of material mechanical properties.
Laser cutting is a promising alternative to the traditional methods in CFRP cutting. However, laser cutting is based on thermal interaction that results in thermal damages of both matrix and fibres. ...The heat affected zone (HAZ) extension is strictly dependent on the adopted laser source and the working parameters. The paper presents an experimental study on the laser cutting of CFRP plate, 1 mm in thickness by means of 150 W Nd:YAG pulsed laser. The cutting region and the influence of process parameters, pulse energy, pulse duration and overlapping, on the kerf geometry and the HAZ were analyzed. Experimental results showed that the adopted laser is able to cut the CFRP plate, up to 10.8 mm/s. However, an accurate selection of the process parameters is necessary in order to obtain the maximum cutting speed and a narrow HAZ. Moreover, a relation between the HAZ extension and the process parameters (average power, cutting speed, pulse frequency and pulse duration) was found.
Understanding the cutting processability of cellulose nanofibril (CNF) films by continuous wave laser is important for precise shape processing that closely follows the design pattern. In this study, ...laser cutting of films made of surface-carboxylated CNFs with various counterionic species was performed to explore the factors that control the cutting processability. The cut width and the thermally affected width are mainly controlled by the laser irradiation energy per unit length. The processed cross section is tapered and rises above the film thickness. NMR analysis suggests that the pyrolysates contain water-soluble cello-oligosaccharides, the molecular weight of which varies with the type of CNF film. We consequently demonstrated that the COOH-type CNF film is preferable to the COONa-type CNF film for reducing the coloration residue and for processing the film into a shape that best follows the designed processing pattern.
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In the present work, laser cutting of Carbon Fibre Reinforced Plastics (CFRP) is investigated by means of a Quasi Continuous Wave (QCW) fibre laser. The adoption of high pulse power (up to 4.5 kW) ...and short pulse duration (0.05 ms) may reduce the HAZ formation and allows high cutting speed. For the aforementioned reasons, the improvement of the laser cutting parameters is industrially relevant, especially on materials that are difficult to cut with the standard modes. To assess the influence of the process parameters on kerf geometry and Heat Affected Zone, experimental tests were carried out fixing the average power at 450W and changing the pulse power, the pulse duration, and the overlapping factor. The tests were performed adopting a full factorial design 33 according to the DoE methodology. ANalysis Of VAriance was used to determine which and how the process parameters affect the kerf geometry and HAZ extension. Results show that the laser allows cutting 1.3 mm-thick CFRP sheets with cutting speed up to 2700 mm/min. Also, by an appropriate selection of the process parameters, it is possible to obtain narrow kerfs (smaller than 200 μm) and a limited HAZ (about 0.5 mm). Besides, the correlation between the inner and the outer HAZ was found: the HAZ measured on the bottom surface can be usefully adopted as a damage index to understand the overall thermal damage since it can be correlated to section HAZ. The latter is the reference damage parameter according to UNI EN ISO 12584 standard.
Glass cutting is widely used in many fields, such as aerospace and integrated electronics. To meet requirements of high-quality glass cutting, methods of full ablation cutting and stealth dicing of ...silica glass using picosecond laser Bessel beam are studied in this paper. Position synchronized output function of laser source and burst mode (BM) can flexibly adjust drilling spacing and the number of sub-pulses during processing. Through experimental research and theoretical analyses, effect of hole spacing, BM, laser power, and defocusing distance on the roughness of the cross-sections of cutting samples are investigated. The optimal combination of full ablation cutting parameters is obtained with the minimum roughness of the cross-section of 355 nm. To expand the application range of Bessel beam glass cutting, stealth dicing process is developed. Process parameters selection strategy of stealth dicing is obtained. Main parameter that affects the effect of stealth dicing is the defocusing distance. Aforementioned methods may provide simple, efficient, and high-quality full ablation cutting and stealth dicing technologies for glass materials.
Real-time, in-situ evaluation of sweat and electrolyte loss under heat stress is critical in preventing the risks of heat-related illnesses and maintaining individual’s physical performance for ...athletes or individuals working in extreme environments. Simultaneous monitoring of sweat rate and sweat chloride concentration via wearable device could provide an accessible route to assess the wastage of fluid and electrolytes. In this work, we report a low-cost, easy-to-manufacture epidermal microfluidic patch via entire laser-cutting scheme and transfer-printing operation. Sandwich-structured sweat rate sensor with trigger sites can induce a high pulse of electrode admittance for quantifying sweat rate when advancing sweat arrives at trigger sites, which favors the sensor inherent higher noise tolerance and independence of sensing on the change of ionic charge. Sweat chloride concentration is also quantificationally analyzed by measuring the admittance of interdigital electrode embedded in the microchannel, representing a simple, practicable, and stable alternative to colorimetric and ion-selective sensors. In-vitro and on-body experiments demonstrate the feasibility and accuracy of continuous measurement for sweat rate and sweat chloride concentration by admittance sensing method. This intrinsically robust, reliable sensing performance of the skin-interfaced microfluidic patch contributes to potential development of such device in personalized medicine.
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•Sandwich-structured sensor with trigger sites can induce a high pulse of electrode admittance for quantifying sweat rate.•Admittance-based method is used for sweat chloride ion quantification.•Pulse based measurement presents higher noise tolerance and independence on the change of ionic charge.
Ceramics possess high thermal and chemical resistance, low density, and high compressive strength; however, the machining complications imposed by their inherent brittleness limit their range of ...applications. Laser cutting technology can offer an automated manufacturing technique for machining these brittle materials. In this paper, a laser cutting method, so-called wobbling, was developed for performing deep, high precision, and defect-free laser cutting of industrial grade alumina ceramics. This work explored picosecond laser process parameters such as focal position, linear speed, and wobble amplitude in order to control cut depth and optimize cut quality in terms of kerf width, kerf taper, surface cleanness, while avoiding crack formation. The morphology and cut quality were evaluated using 3D laser scanning microscopy and scanning electron microscopy (SEM). Picosecond laser cutting process parameters were optimized, achieving a maximum material removal rate of ~10 mm3/min. It was shown that the laser cutting process developed via these experiments represents an effective and efficient manufacturing tool that can be incorporated in engineered net shaping systems.
We developed the laser oxyfuel and oxyflame hybrid (LOXAFH) cutting method which has the potential to break the limit by integrating laser and oxyfuel cutting methods. The LOXAFH cutting method was ...designed through numerical simulation, and verified through clad plate cutting experiments. Furthermore, the influence of heat sources composed of 1 kW laser beams, oxygen jet flow, and flame which contribute to the melting of the clad plate was analyzed. Controlling factors such as laser input, preheating flame, and oxygen jet flow were found to be crucial in achieving optimal cutting results. The nozzle shape, particularly the converging-diverging nozzle, showed superior performance in the effective oxidation-induced melting and removal of molten slag. 500 W LOXAFH cutting demonstrated the ability to cut clad plate up to 15 mm thick.
•Development of the convergence cutting technology: combining laser cutting and oxyfuel cutting.•Overcoming the limitations of traditional methods by complementing the limitations of laser cutting and oxyfuel cutting.•Potential to cut thick clad plates consisting of non-oxidizable metal with oxidizable metal.
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