Error assessment of laser cutting predictions by semi-supervised learning

Experimentation data of perspex glass sheet cutting, using CO2 laser, with missing values were modelled with semi-supervised artificial neural networks. Factorial design of experiment was selected for the verification of orthogonal array based model prediction. It shows improvement in modelling of edge quality and kerf width by applying semi-supervised learning algorithm, based on novel error assessment on simulations. The results are expected to depict better prediction on average by utilizing the systematic randomized techniques to initialize the neural network weights and increase the number of initialization. Missing values handling is difficult with statistical tools and supervised learning techniques; on the other hand, semi-supervised learning generates better results with the smallest datasets even with missing values.

Joint Performance for Laser Cutting-welding of Zinc-coated Tailored Blanks

The process of laser bull welding of zinc-coated steel（SGCD3 and WLZn）blanks was presented.whose edges were prepared by laser cutting.The properties of the butt joints.such as tensile strength.bending,stamping.weld shape,and corrosion-resisant were tested.The experiments of laser cutting and welding were carried ont on a custom-made system designed.which is a set of equipment for wide sheet butt welding based on a laser cutting-welding combination process.The experiments proved the technological feasibility of laser butt welding for thin zinc coated steel sheets whose edges were prepared by laser cutting on the same equipment.

Prediction and Analysis of Surface Quality of Northeast China Ash Wood during Water-Jet Assisted CO_(2) Laser Cutting

As a natural and environmentally friendly renewable material,Northeast China ash wood(NCAW)(Fraxinus mandshurica Rupr.)was cut by water-jet assisted CO_(2) laser(WACL),the surface quality was evaluated by surface roughness of cut section.The surface roughness was measured by three-dimensional(3D)profilometry.Furthermore,the micromorphology of machined surface was observed by scanning electronic microscopy(SEM).Carbon content changes of machined surface were measured by energy dispersive spectrometer(EDS).A relationship between surface roughness and cutting parameters was established using response surface methodology(RSM).It is concluded that the cutting speed,laser power and water pressure played an important role in surface roughness of cut section.The surface roughness increased as an increase in laser power.It decreased caused by increasing of cutting speed and water pressure.Measurements revealed that the surface quality of NCAW part was improved using the optimized combination of cutting parameters.The established quadratic mathematical model of a good prediction is helpful for matching suitable cutting parameters to obtain expected surface quality.

AN EXPERIMENTAL STUDY OF CO_2 LASER CUTTING OF METALLIC COATED SHEET STEELS

An experimental investigation is outlined for the CO 2 laser cutting process of metallic coated sheet steels, GALVABOND. It shows that by proper control of the cutting parameters, good quality cuts are possible at high cutting rate. Visual examination indicates that when increasing the cutting rate to as high as 5000 mm/min (about 100 times that suggested previously), kerfs of better quality can be achieved. Some kerf characteristics such as the width, heat affected zone and dross in terms of the process parameters are also discussed. A statistical analysis has arrived at a recommendatio on the optimum cutting parameters forprocessing GALVABOND.

Prospects of Robot Laser Cutting in the Era of Industry 4.0

Laser cutting is a non-contact thermal cutting process and an integral part of manufacturing. In metal processing, laser cutting is at the forefront of the manufacturing chain followed by joining and manufacturing processes like welding. The future of metal manufacturing processes like laser cutting shall rely on intelligent systems such as automation and robotics based on the advancement of technology and digital transformation spearheaded by Industry 4.0. Moreover, the digital transition where robots and automated systems are key drivers creates a broader platform to utilize energy-efficiency materials. Such energy-efficient materials include high-strength steels (HSS) for structural applications (e.g. bio-energy structures, wind turbines, ice-going vessels) onshore, offshore and in the Arctic region. The aim of this paper is to elucidate the prospects of robot laser cutting systems in the framework of integrated metal manufacturing in future factories. Previous studies on laser cutting technologies are examined based on scientific and industrial perspectives. Robot laser cutting system is compared with the well-known flat-bed laser cutting CNC machine in several aspects including flexibility in manufacturing, ease for digitalization, off-line capabilities and investment analysis. The findings shall help to determine the competitiveness of robot laser cutting systems with flat-bed laser cutting CNC machines, especially when considering metal manufacturing in small and medium-sized enterprises (SMEs). The outcome of this study is to stir up experimental and computational research on robot laser cutting systems of metals, and help companies in their decision-making process when deciding which laser cutting system will best suit their manufacturing operations in the future.

Magnetic Kirigami by Laser Cutting

Magnetic kirigami with tunable configurations under magnetic actuation is of significant interest in various emerging fields.However,there remains a grand challenge to develop magnetic kirigami with a facile fabrication strategy,programmable mag-netization,and functionality.In this work,we present a novel magnetic kirigami that is readily fabricated by the laser cutting technique.The magnetic kirigami consists of an array of magnetic microplates,each with a programmed magnetization.By applying an actuation magnetic field,each microplate can rotate and even flip,allowing for predesigned kirigami configura-tions.By further coating the surface of the microplate array,the magnetic kirigami can be programmed with functionality.We demonstrate a potential application of information encryption by engineering magnetic kirigami into a magneto-responsive QR code.Providing a simple fabrication strategy,our work paves the way for other applications of magnetic kirigami.

Laser cutting of thermoplastic film:Mechanism and processing technology

The mechanism of ultraviolet(UV) nanosecond laser cutting of thermoplastic films and the influence of process parameters on process quality are systematically discussed.The photothermal effect plays a dominant role in the interaction between the UVnanosecond laser and thermoplastic materials.In this photothermal reaction,a heat source with the focal point as the core is formed,around which a thermal carbonization layer,a thermal melting layer,and a thermal expansion layer are formed in order from the inside to the outside.Among them,the thermal carbonization layer is not prevalent,and the thermal melting layer and thermal expansion layer are prevalent.The process quality can be adjusted by adjusting the cutting speed,the laser power,and the repetition number of cuts to regulate the process of heat generation and heat dissipation.In the effective range,the faster the cutting speed and the lower the laser power,the smaller the kerf width and heat-affected zone(HAZ) width.Within a certain range,the depth of kerf can be increased by increasing the repetition number of cuts.

Analysis and comparison of laser cutting performance of solar float glass with different scanning modes

Cutting quality and efficiency have always been important indicators of glass laser cutting.Laser scanning modes have two kinds,namely,the spiral and concentric circle scanning modes.These modes can achieve high-performance hole cutting of thick solar float glass using a 532-nm nanosecond laser.The mechanism of the glass laser cutting under these two different scanning modes has been described.Several experiments are conducted to explore the effect of machining parameters on cutting efficiency and quality under these two scanning modes.Results indicate that compared with the spiral scanning mode,the minimum area of edge chipping(218340µm)and the minimum Ra(3.01µm)in the concentric circle scanning mode are reduced by 9.4%and 16.4%respectively.Moreover,the best cutting efficiency scanning mode is 14.2%faster than that in the spiral scanning mode.The best parameter combination for the concentric circle scanning mode is as follows:Scanning speed:2200 mm/s,number of inner circles:6,and circle spacing:0.05 mm.This parameter combination reduces the chipping area and sidewall surface roughness by 8.8%and 9.6%respectively at the same cutting efficiency compared with the best spiral processing parameters.The range of glass processing that can be achieved in the concentric circle scanning mode is wider than that in the spiral counterpart.The analyses of surface topography,white spots,microstructures,and sidewall surface element composition are also performed.The study concluded that the concentric circle scanning mode shows evident advantages in the performance of solar float glass hole cutting.

Taper Angle Correction in Cutting of Complex Micro-mechanical Contours with Ultra-Short Pulse Laser

The objective of this work was to investigate the possibility of taper angle correction in cutting of complex micro-mechanical contours using a TruMicro ultra-short pulse laser in combination with the SCANLAB precSYS micro machining sub system. In a first step, the influence of the process parameters on the kerftaper angle of metallic alloys was systematically investigated without beam inclination. A set of base parameters was derived for the subsequent investigations. In a second step, the kerftaper angle was controlled by static beam inclination. In a third step, the same optics was used in its dynamic precession mode to fabricate micro-mechanical components of complex contours with perpendicular 0~ taper angles. It was found that taper angle adjustments of up to 7.5~ are possible with the used setup for cutting applications. Taper angle control is possible both in the static beam inclination mode and in the dynamic precession mode. The static mode could be interesting for contours with sharp inner radii and for achieving faster cutting times similar to results with fixed optics, but would require excellent synchronization of beam inclination and axis motion. The dynamic precession mode would allow an easier integration of the optics into a laser machine but will result in longer cutting times and limitations with respect to achievable inner radii.

Dimethicone-aided laser cutting of solar rolled glass

Solar rolled glass,with one micro-structure surface and another roughness surface,can cause diffuse refraction of the focused laser spot,and this phenomenon restricts the application of laser manufacturing.In this study,laser cutting of solar rolled glass with a thickness of 2.5 mm was successfully achieved with the help of dimethicone to ensure laser focusing.Dimethicone was coated on the top surface of the rolled glass processing zone,and a bottom–up multilayer increment with the spiral line was applied to control the cutting path.Different viscosity values of dimethicone were considered.Results showed that surface quality increased as the viscosity increased until a certain threshold was reached;afterward,the surface quality decreased or directly caused the cutting to fail.The minimum surface roughness(3.26µm)of the processed surface(chipping:Width≤113.64µm,area 215199µm)was obtained when the dimethicone viscosity and laser pulse frequency were 1000 mm/s and 43 kHz(power 25.4 W),respectively.The micro-defects on the processed surface were few,and the edge chipping width and depth of the laser processed surface were small.

Numerical Analysis and Experimental Study of the Effect of Workpiece Thickness on Flow Field in Laser Cutting

Based on Navier-Stokes equation and renormalization group(RNG) onflow model,the 3D symmetrical impinging jet model of laser cutting is established by adopting a taper nozzle and a convergence nozzle. Numerical simulation of gas flow in laser cutting is used to investigate the effect of workpiece thickness on flow field of assist gas in cutting slot. The isolines of static pressure as well as the distributions of static pressure and velocity are analyzed in details with different workpiece thickness,and the trend of dynamics characteristics of gas jet is shown in the study. For taper nozzles and convergence nozzles,the dynamic structure of assist gas being close to the lower surface of workpiece is exacerbated while the cutting quality and cutting effciency become worse with the increasing of workpiece thickness. The parallel degree between assist gas and the axis of convergence nozzle is better than that of taper nozzle after the gas goes out of the nozzles. Two typical subsonic nozzles are designed for the cutting experiment at the end of the paper.

Experimental Study on Inert Gas-assisted Laser Cut Veneer Based on LOM

Based on the LOM(Laminated Object Manufacturing)process,an inert gas-assisted laser method for wood cutting was proposed.The carbonization degree of wood surface was improved by the introduction of helium(He)gas,and the influence of process parameters on the carbonization layer of wood surface was solved,it was significance to reduce the post-processing of LOM and improve the quality of forming workpiece.The cherry wood veneer was used as the experimental material,under the condition of the same process parameters,the wood was cut with or without inert gas-assisted,and the influence factors of kerf quality were studied by variance analysis.The results showed that under the same condition,compared with traditional laser processing,the kerf width was obviously reduced in the inert gas-assisted cutting.Because the He gas had oxygen-isolation and flame retardant effect,which prevented heat accumulation and conduction.The micro morphology of the kerf surface showed that the flatness was better in the inert gas-assisted cutting.As the excess heat was blown out by the cooling and purging of the gas,the phenomenon of oxidation and burning was reduced,the range of HAZ(heat affected zone)was reduced,and the carbonization phenomenon was obviously improved.The surface quality of kerf was improved effectively.According to the analysis of variance,in addition to the effect of laser power,cutting speed and inert gas flow on the cutting width,the interaction between inert gas flow and laser power,laser power and cutting speed were also the main factors which affected the cutting width.The feasibility of the combined inert gas and laser processing to improve wood cutting quality has been verified through experimental research,which provided a certain reference for the followup research on improving the wood processing quality.

Mechanical Properties of Remote-Laser Cut CFRP and Thermographic Laser-Process Monitoring

Remote-laser beam cutting is a productive technology without tool wear. Especially when cutting carbon fiber reinforced polymers (CFRP), it offers constant manufacturing quality. Since it is a thermal process, a heat-affected zone (HAZ) is formed at the edge of the cut. Based on quasi-static and cyclic mechanical tests on open-hole specimens, the influence of the process on the mechanical properties of CFRP is shown. The quasi-static tests are in good correlation with results from other researchers by indicating an increase in the maximum tensile stress of the test specimens, cut by remote-laser. The reason is the rearrangement of the shear stresses and a reduction of the notch stress concentration. However, the results of the present study show that excessive expansion of the HAZ leads to a reduction in the maximum tensile stress compared to milled test specimens. Under cyclic load conditions, remote-laser beam cutting does not lead to a more pronounced degradation than milling. The mechanical properties of the notched test pieces are sensitive to the expansion of the HAZ. For the production of components it is therefore necessary that the remote-laser beam cutting is carried out under controlled and documentable conditions. For this purpose, process thermography was tested as a tool for quality assurance. The results show that the technology is basically suitable for this task.

Laser Processing Mechanism of Monocrystalline Diamond

When a Nd：YAG laser, the wavelength of which is permeable for diamond, is focused on the surface of a diamond sample, a layer of surface material is ablated. Therefore, diamond can be cut by repetitive irradiation. In this study, the processing mechanism of ablation for a single crystal diamond was examined using a heat conduction analysis, considering laser absorption at the surface or the temperature dependence of absorption coefficient. When the laser beam is absorbed at the surface layer, the surface layer is ablated during an early period in the laser pulse. Once the absorption surface layer is ablated, the laser beam penetrates the base material and ablation stops. On the other hand, if the authors assume that single crystal diamond has the temperature dependence of absorption coefficient which is about equal to that of CVD （chemical vapor deposition） diamond, the temperature rise is not enough to ablate the material. However, it became clear that the diamond is ablated deeply when the authors consider both absorption at the surface layer and the temperature dependence of the absorption coefficient. It can be considered that the surface is transformed to graphite and becomes the absorption layer during the repetitive irradiation. It is estimated that the phase change to graphite is very small and its volume fraction is a few percent at most.

Laser material processing optimization using bayesian optimization: a generic tool

Optimizing laser processes is historically challenging,requiring extensive and costly experimentation.To solve this issue,we apply Bayesian optimization for process parameter optimization to laser cutting,welding,and polishing.We demonstrate how readily available Bayesian optimization frameworks enable efficient optimization of laser processes with only modest expert knowledge.Case studies on laser cutting,welding,and polishing highlight its adaptability to real-world manufacturing scenarios.Moreover,the examples emphasize that with suitable cost functions and boundaries an acceptable optimization result can be achieved after a reasonable number of experiments.

Controlling the laser induction and cutting process on polyimide films for kirigami-inspired supercapacitor applications

The recently emerging laser-induced graphene(LIG)technology,with one-step processing and designable features,has been widely used in the fabrication of wearable/portable electronics.Herein,by taking inspiration from kirigami,we designed a stretchable supercapacitor(SC)step by step through controlling laser induction and cutting process on the polyimide(PI)film,with the use of one single CO_(2) laser source.Firstly,the carbonized basic geometric units of lines were produced on PI films to investigate the processing-structure relationships.Then,the complex photothermal conversion and heat transfer progress involved in the carbonized process were simulated by a photothermal model.Both experimental and theoretical results suggested that the laser power,scan rate and focus condition have great influence on the size,shape and morphology of the carbonized lines.Finally,we optimized the parameters of laser induction and cutting process to fabricate the kirigami-inspired SCs with reliable electrochemical properties and editable mechanical flexibility,showing great potential in the field of flexible electronics.

Acoustic Properties of Micro-Perforated Panels Made from Oil Palm Empty Fruit Bunch Fiber Reinforced Polylactic Acid

This paper presents the development and performance of micro-perforated panels(MPP)from natural fiber reinforced composites.The MPP is made of Polylactic Acid(PLA)reinforced with Oil Palm Empty Fruit Bunch Fiber(OPEFBF).The investigation was made by varying the fiber density,air gap,and perforation ratio to observe the effect on the Sound Absorption Coefficient(SAC)through the experiment in an impedance tube.It is found that the peak level of SAC is not affected,but the peak frequency shifts to lower frequency when the fiber density is increased.This phenomenon might be due to the presence of porosity in the inner wall of the holes.Increasing or decreasing the air gap and perforation ratio shifts the peaks of acoustic absorption either way.

The Comprehensive Control of Astigmatism during and Following Intraocular Lens Implantation.

The operating corneoloscope and Terry operative keratometer were used respectively in 29 and 34 eyes during the intraocular lens implantation to measure the corneal astigmatism qualitatively or quantitatively,so that the tension of incision closure could be adjusted. The surgically induced astigmatism in qualitative group two weeks after the operation was 3. 5 ± 1. 70 D and that in quantitative group was 2. 56±1. 60 D. There were 55.17% and 38. 24% of the eyes with over 2. 00 D corneal astigmatism in qu...

All-Ti3C2TA:MXene Based Flexible On-chip Microsupercapacitor Array

Flexible on-chip microsupercapacitors(MSCs)are highly desired for integrated wearable or portable elec-tromics due to their advantages of small size,high power density,easy integration,long lifespan,high security,and tlexibility.The output voltage of MSCs can be improved by designing MSC arrays,which could further expand their application fields.In this work,we proposed a facile laser direct cutting method to prepare an on-chip flexible MSC array using TiC,T,MXene as both current collector and electrode materials.The designed MSC in PVAH2SO4 all-solid-state gel electrolvte exhibits a large volume/areal capacitance of 770.72 F/cm^3(46.24 mF/cm^2)at a scan rate of 20 mV/s,a high energy density of 68.51 mWh/cm^3 at a power density of 6.16 W/cm^3,excellent cveling stability with capacitance retention of 98.50%after 10000 charge/discharge cvcles.The MSC also shows superior flexibility and stabilitv even after repetition of charge/discharge cvcles under the convex and concave bending states.In addition.the assembled MSC array(4 in series)provides a high voltage of 3.2 V,which could easily power a purple light-emitting diode more than 10 min,demonstrating its potential application in integrated portable/wearable devices.

Photolithography-free fabrication of photoresist-mold for rapid prototyping of microfluidic PDMS devices

Traditional soft lithography based PDMS device fabrication requires complex procedures carried out in a clean room. Herein, we report a photolithography-free method that rapidly produces PDMS devices in 30 min. By using a laser cutter to ablate a tape, a male photoresist mold can be obtained within 5 min by a simple heating-step, which offers significant superiority over currently used photolithographybased method. Since it requires minimal energy to cut the tape, our fabrication strategy shows good resolution(~ 100 μm) and high throughput. Furthermore, the micro-mold height can be easily controlled by changing the tape types and layers. As a proof-of-concept, we demonstrated that the fabricated PDMS devices are compatible with biochemical reactions such as quenching reaction of KI to fluorescein and cell culture/staining. Collectively, our strategy shows advantages of low input, simple operation procedure and short fabrication time, therefore we believe this photolithography-free method could serve as a promising way for rapid prototyping of PDMS devices and be widely used in general biochemical laboratories.