Engraving Process Research Articles

Research of the In-process Artillery Shot in Terms of Projectile Band-engraving

The paper considers, in the classical treatment of an artillery shot, a pyrostatic (preliminary) shot period during which a projectile is assumed to be motionless until the pressure of the powder gases becomes equal to the conditional shot-start pressure. The latter is determined by the maximum force of resistance to the driving band completely engraved by rifling, with resistance related to the projectile cross-section area. In actual practice, the engraving is a gradual process (in this case the shot period is called a forcing one). A level of the axial inertial forces may even be sufficient for fuse arming of inertial safety devices. The fact that there is a need to have a sufficiently large set of the appropriate design and physical parameters, which are, usually, incompletely known, hinders the use of a rigorous calculation technique. To simplify the inter ballistics calculation, an analytical approximation of the engraving curve is proposed. For its description it is necessary to know the maximum force of resistance (or the shot-start pressure), the width of the driving band and the total travel of a projectile when engraving. Thus, it is assumed that after complete engraving of the driving band the resistance super-quickly drops to zero, and an appropriate jump in the acceleration (setback) curve of the projectile occurs. For the first time, it is proposed to include the number of inter ballistic parameters into the work of powder gases, thus ensuring an automatic integration of the system of equations regardless of the specific description of the engraving curve (in some cases, analytical integration needed for calculation may be impossible). The example of calculation for the 122-mm D-30 howitzer illustrates a practical application of the proposed technique. Comparison of calculation results using the traditional and proposed techniques is made to show that the integral characteristics of the shot are close. It is found that a progress of the engraving process is relatively slow, and a level of the maximum resistance force is reached almost at the very end of the forcing period. It should be noted that the pressure in the firing chamber can many folds exceed the forcing one. An available specific S-shaped initial section of the acceleration (setback) curve of the projectile is revealed, which is confirmed by experiments. The final values of the ballistic parameters are close to those obtained by a more rigorous technique.

Visual Language and ‘Paintaglios’ of Gerald Chukwuma: A Critical Analysis

Gerald Chukwuma is a prolific Nigerian artist whose creative adaptation and use of media tend to deviate from common practice. This essay draws on his several avant-garde works on display at the Nnamdi Azikiwe Library and at the administrative building of the University of Nigeria Nsukka. These artworks are referred to as ‘paintaglio’ in this essay owing to the convergence of painting, and engraving (or intaglio) processes. This study therefore identifies, critically interprets and analyzes Chukwuma’s artistic inclinations—style, spirit, forms, materials, and techniques. This is in order to lay bare the formal and conceptual properties that foreground the artist’s recent paintaglio experiments. The study relies on personal interviews, literature, and images of Chukwuma’s works as data. Such experimental works which clearly express influences of ‘natural synthesis’ ideology are here examined against the backdrop of their epistemic themes.

Optimization of surface engraving quality with ultrafast lasers

Large area engraving is achieved by moving a focused femtosecond beam on the sample surface. Of course, the process parameters are the moving speed (moving beam or moving sample or both) and the laser repetition rate. Surface engraving is obtained by multiple linear pass shifted along the y-axis perpendicular to the moving x-axis. The resulting surface shape is thus highly dependent on the deviation Δy between two successive shifted passes. Being able to predict and optimize the process in terms of the depth and surface quality is a key advantage. In this work, we show that experimentally engraved surface shapes can be numerically estimated using a simple ablation model. Only two parameters are needed to have a satisfactory description of the laser matter interaction for a given material. We combine the description of the engraving process with the laser matter interaction model to calculate the surface shape after laser scanning.

Niekonwencjonalne procesy kształtowania materiałów ceramicznych i kompozytowych

In order to reach the high quality parts of machines or tools very often ceramic or composite materials on metalic or ceramic base are being applied. Efficient shaping above mentioned materials using cutting or classical grinding is difficult because of their high mechanical properties. Rational solution is application of unconventional machining methods as: electrochemical, electrodischarge or electrochemical – electrodischarge (ECDM) in case when machined materials are at least partly conductive of electrical current. In case of shaping ceramic materials unconductive for electrical current the rational solution can be application of Spark Assisted Chemical Engraving (SACE) process – the special kind of ECDM process.

Tattoos in pre-Islamic poetry, a study in the light of social reality

- The research study on the origins of tattooing, in its historical depth, revealed the emergence of this phenomenon in totemic religions. It was believed that the blood coming out during the engraving process makes the image of the totem blend spiritually and materially with its totem, so that it and the totem marked with it share the same characteristics. - Tattoos are used for adornment purposes or to treat some tumors and pains, and they have to do with ideas of witchcraft, and tattoo marks help define a person and his affiliation to a particular sect or tribe. A tattoo is drawing a specific shape that is engraved on a part of the skin of the human body with a needle prick and a dye of a certain color is sprayed on it, to interact with the blood oozing from the needle prick, leaving a permanent and unchanged effect on the skin. The tattoo engraved is part of the tattoo process and not the tattoo itself. -

Quasi-static and dynamic engraving of small caliber projectile

The engraving process of projectile is one of the main topics of interior ballistics and has not been well known till now. Our study focuses on engraving small calibre projectile under quasi-static and dynamic loading conditions. Quasi-static tests were carried out on a MTS 810 and a gas gun-based test rig was specially designed to perform the dynamic tests. The hoop and axial strains of the outside surface of the gun barrel were monitored and analysed to reflect the interaction between the projectile and the barrel. The effects of projectile structure and loading rate on the engraving process were investigated. The experimental results showed that severe friction between the projectile and gun bore occurs and plastic deformation of the copper layer increases the engraving resistance. Changes in force and strain under different conditions indicate that many factors including projectile structure and loading rate have great influences on the engraving process. [Received 20 July 2016; Accepted 16 November 2016]

Numerical Simulation of Gun Bore Damage during Engraving Process of Driving Band

A Damage mechanics finite element numerical computation method was established based on HLC microscopic damage model to solve the problem of damage, crack initialization and growth inside bore during the firing process. The damage and failure process of the bore surface was simulated numerically during multiple rounds of firing. The law of the barrel material performance changing with the number of firing rounds was analyzed during the engraving process of the driving band and compared with the experimental results. It is proved that HLC microscopic damage model can show the complicate damage behavior and predict the cracking defect, which provides a reference for safety design of the gun barrel.

Modeling and dynamic simulation on engraving process of rotating band into rifled barrel using three different numerical methods

The FEM (finite element method), FEM-SPH (smoothed particle hydrodynamics method) adaptive coupling method and the coupled Eulerian-Lagrangian method (CEL) are introduced to simulate the engraving process. Eight-node hexahedral elements were mainly used to build the finite element models of the rotating band engraving into the gun barrel except in CEL simulation. In this case, the rotating band model and mesh are both built in ABAQUS in order to meet the requirements of CEL simulation. The simulation results include the deformation process of the rotating band, the motions of the projectile, the dynamic engraving resistance and the calculating efficiency were obtained, compared and analyzed. The advantages and disadvantages of numerical methods when simulating engraving process are discussed. The results show that the FEM-SPH adaptive coupling method and the CEL method have advantages for applications involving the simulation of the engraving process. The intent is to better understand the numerical methods and eventually broaden the utilizations in analyses of interior ballistics.

Mathematical Modelling and Simulation Research of Thermal Engraving Technology Based on PMMA Material.

We proposed a thermal engraving technology based on heat transfer theory and polymer rheology in microfluidic field. Then, we established a 3D model of the thermal engraving process based on polymethyl methacrylate (PMMA) material. We could employ the model to analyze the influence of temperature and speed on microchannel processing through the finite element simulation. Thus, we gained the optimal processing parameters. The orthogonal experiments were carried out within the parameter ranges obtained by the simulation results. Finally, we fabricated the smooth microchannel, the average roughness of which was 0.3 μm, by using the optimal parameters. Furthermore, we examined the surface morphology and wettability. Our work provides a convenient technological support for a fast, low-cost, and large-scale manufacturing method of microfluidic chips.

Preparation of the projectile rotating band and its performance evaluation

Alternative materials are being investigated as substitution of the traditional copper rotating band, in order to solve problems associated with their mechanical and physical properties. Meanwhile, new processes for joining the rotating band on the projectile body have also to be developed because of different material physical properties. In this paper, swaging, welding, and newly developed spraying technologies for fabricating rotating band are analyzed, respectively. Quasi-static and dynamic engraving methods are presented for evaluating the performance of as-prepared rotating band. The former was performed on an 810 Material Testing System and the latter was carried out by using a specially developed gas-gun-based impact test rig. Hoop and axial direction strain gauges were positioned on the exterior of the barrel to monitor the effect of the rotating band on the barrel during engraving process. It is suggested that aluminum bronze coating prepared by the High Velocity Arc Spraying (HVAS) process should be a good candidate for application to a rotating band of medium- and large- caliber projectiles. The measured strains were found to be dependent on a set of variables, such as loading rate, band material and structure, forcing cone and rifling (land and groove) structure, bore condition (oiled or dry), etc. The loading rate has been verified as the most important factor and the essential difference among quasi-static engraving, dynamic engraving, and actual firing.

An Artificial Neural Network Model for Prediction of Colour Properties of Knitted Fabrics Induced by Laser Engraving

In this paper, we propose an artificial neural network (ANN) model for prediction of color properties, including color yield (in terms of K/S value) and CIE L, a and b values of 1005 cotton knitted fabrics under the effect of laser engraving process with different process parameters. Fabric factors to be examined in the ANN model included fiber composition, fabric density, mass of fabric, fabric thickness, linear density of yarn, yarn twist, direction of yarn twist and crimp. After obtaining the ANN model, its performance was compared with linear regression model. It is noted that the ANN model produced superior results in prediction of color properties of laser engraved 100 % cotton knitted fabrics. The relative importance of the examined factors influencing color properties was also investigated.

The effect of laser engraving on aluminum foil-laminated denim fabric

In this paper, a developed textile design method combining laser engraving and foil lamination was explored. With the foil laminating, the surface of denim fabric shows shinning effect. After that, the foil-laminated denim samples were treated with laser engraving by adjusting the parameters, including resolution (dots per inch, dpi) at 20, 30, 40 and 50 dpi and the pixel time (microsecond, μs) at 120 and 180 μs to melt and evaporate the aluminum foil and some surface fibers. The properties of the laser-engraved foil-laminated denim fabric, including weight, tearing strength, air resistance, surface observation, color appearance, colorfastness and abrasion resistance, and some low-stress mechanical properties, were investigated. The experimental results revealed that the changes in these properties are mainly related to the melted and evaporated surface laminated aluminum foil and different sizes of cracks, wrinkles and pores formed on the fiber surface with the increment of laser energy applied. This study also revealed the potential of pattern creation with different values and reflective appearance for the embellishment of denim fabric combining the aluminum foil laminating method through the laser engraving process. With lower resolutions, engraved vague patterns with small laser beam dots can be achieved. While the treatment resolution increased, clear patterns could be performed. Based on the same resolution, the higher pixel time can export more energy, which makes the pattern look more clearly. This design approach opens up new possibilities for metallic denim fabric design without any chemicals used.

Effect of Pulse Length on Engraving Efficiency in Nanosecond Pulsed Laser Engraving of Stainless Steel

Dependency of laser pulse length on the effectiveness of laser engraving 304 stainless steel with nanosecond pulses was investigated. Ytterbium fiber laser with pulse lengths from 4 to 200 ns was used at a constant average power of 20 W. Measured criteria for effective laser engraving were high material removal rate (MRR), good visual quality of the engraved surface, and low processing temperature. MRR was measured by weighing the samples prior and after the engraving process. Visual quality was evaluated from magnified images. Surface temperature of the samples was measured by two laser spot-welded K-type thermocouples near the laser-processed area. It was noticed that MRR increases significantly with longer pulse lengths, while the quality decreases and processing temperature increases. Some peculiar process behavior was noticed. With short pulses (<20 ns), the process temperature steadily increased as the engraving process continued, whereas with longer pulses the process temperature started to decrease after initially jumping to a specific level. From visually analyzing the samples, it was noticed that the melted and resolidified bottom structure had cracks and pores on the surface when 50 ns or longer pulse lengths were used.

Diamond micro engraving of gravure roller mould for roll-to-roll printing of fine line electronics

Printing electronics has attracted great attention in recent years due to its various superior performances compared with conventional silicon-based semiconductor industry. Roll-to-Roll gravure printing is able to transfer conductive nanoparticle ink onto the flexible film substrate to form continuous fine metal lines using a gravure roller mould with tens of thousands of tiny gravure cells on its surface. However, it is difficult to scale down the printed line width, which is crucial for the film's circuit density, resolution and transparency, because the market-available rollers fabricated by conventional engraving techniques for graphic printing usually have gravure cells larger than 25μm. Hence, in this study, a novel method based on ultraprecision machining technology, Diamond Micro Engraving (DME), is introduced to miniaturize the gravure cells in order to reduce the ink volume transfer during the printing process. A V-shape sharp diamond tool is used to continuously generate concave inverted micro pyramidal structures on the gravure roller surface using the Slow Slide Servo technology. Geometrical modelling of the engraving process is conducted to help programming the tool path to realize accurate control of the instantaneous position of two linear axes and one rotatory axis. Through applying the DME process, generation of consistent cell structure is achieved. The engraved gravure cell width is successfully miniaturized to 7μm. With the optimized cell spacing value, the DME-machined roller moulds are used in gravure printing of metal mesh film, which works as a potential transparent conductive film to replace the expensive indium-tin-oxide (ITO). The printed line width is reduced from 47μm to 19μm, and the transmittance of the printed metal mesh film for visible light is increased from 65.2% to 80.4% accordingly, which is comparable to the transmittance of ITO film.

Actual Diamond Engraving of a Fullerene Coated Glass Plate

In this paper, we present the results of fullerene film engraving using a diamond tool. Based on available literature data, to our knowledge the fullerene film machinability is not explored in literature. Therefore, we have investigated wear mechanisms of the engraving process that could be used in micromachining. The engraving process parameters were estimated on the basis of poor quality groove's edge. The flat diamond tip, which remains after wear, has a pitted surface which was observed with a digital optical microscopy and identified using AFM. Soot-like wear debris was observed and spectroscopically analyzed. FTIR spectroscopy results strongly indicate that fullerene C60 disappears as a molecule and interacts with oxygen, nitrogen and water vapor from the atmosphere. The occurrence of tool wear and wear debris were observed by nondestructive thermography testing. Results confirm that development of high temperature in a cutting zone of 1556°C causes extensive thermo-chemical tool wear.

Fatigue fracture of cutter blade made of high-speed steel

The quality of the surface of cyclically loaded components is very important. Many observations confirm that the root cause of the micro cracks (causing the fatigue fracture) are primarily a surface's defects appearing during production process. These surface defects can be also caused by engraving processes used to perform identification marks. This paper presents the failure analysis of broken blade of the cutter Ku 500VX. The blade was subject of standard metallographic examination, hardness measurements, fractography analysis and metallographic studies using stereoscopic, light and scanning electron microscopes. The damage of the blade was caused by changes of the structure (formation of the brittle micro dendritic structure) that occurred during manual electric engraving process when the material was heated till its melting point. As a result the stresses occurred in surface what provided to micro cracking and to propagate the fatigue fracture. The origin of this fatigue fracture was in the place where the inscription was made.

Tribology of rotating band and gun barrel during engraving process under quasi-static and dynamic loading

Abstract The engraving process of a projectile rotating band is one of the most basic research aspects in interior ballistics, which has not been thoroughly understood thus far. An understanding of this process is of great importance from the viewpoints of optimal design, manufacturing, use, and maintenance of gun and projectile. In this paper, the interaction of copper and nylon rotating bands with a CrNiMo gun barrel during engraving was studied under quasi-static and dynamic loading conditions. The quasi-static engraving tests were performed on a CSS-88500 electronic universal testing machine (EUTM) and a special gas-gun-based test rig was designed for dynamic impact engraving of the rotating bands. The mechanical behaviors of copper and nylon were investigated under strain rates of 10−3 s−1 and 2 × 103 s−1 using an MTS 810 and a split Hopkinson pressure bar (SHPB), respectively. Morphologies of the worn surfaces and cross-sectional microstructures were observed with scanning electron microscope (SEM) and optical microscope (OM). It was found that large deformation and severe friction occur during engraving. The surface layer is condensed and correlated with a hardness gradient along the depth from the top worn surface. The structure of the rotating band and gun bore, band material, and loading rate have great effects on band engraving. The flow stress-strain of the copper strongly depends on the applied strain rate. It is suggested that strain rate and temperature play significant roles in the deformation mechanism of rotating bands.

CO2 Laser Manufacturing of Miniaturised Lenses for Lab-on-a-Chip Systems

This article describes the manufacturing and characterisation of plano-convex miniaturised lenses using a CO2 laser engraving process in PMMA substrates. The technique allows for lenses to be fabricated rapidly and in a reproducible manner at depths of over 200 µm and for lens diameters of more than 3 mm. Experimental characterisation of the lens focal lengths shows good correlation with theory. The plano-convex lenses have been successfully embedded into capillary microfluidic systems alongside planar microlenses, allowing for a significant reduction of ancillary optics without a loss of detection sensitivity when performing fluorescence measurements. Such technology provides a significant step forward towards the portability of fluorescence- or luminescence-based systems for biological/chemical analysis.

Research on the Key Technology of Laser Engraved Image

In 1960 the first ruby laser came out , after 40 years’ development, laser engraving technology has been widely used in various areas. This paper describes the characteristics of laser engraving, the advantages and applications in industries and study images of laser engraving key technologies in-depth from image processing, laser engraving process parameters and clean carbide processing , and JK-2030 CO2 laser engraving machines on paulownia color photos as examples for authentication, making laser engraving images more easily and efficiently .

Friction and wear between rotating band and gun barrel during engraving process

It is of great importance to investigate the occurrence of engraving (also known as “scoring”) of rotating bands during firing to achieve optimal design, manufacturing, use and maintenance of medium and large caliber rifled guns and their corresponding projectiles. In our present study, two short rifled gun barrel sections and projectiles with copper, Al–bronze and nylon rotating bands were prepared. Quasi-static and dynamic push tests were performed on the CSS-88500 Electronic Universal Testing Machine (EUTM) and a specially designed gas gun-based dynamic impact test rig. The quasi-static experimental results showed that the extruded materials accumulates at the end of the band and has not departed from the band base. However, the dynamic experimental results showed no clear accumulation, which is close to the recovered rotating band after firing. Large deformation and severe friction between rotating band and gun bore has occurred during engraving process. It is suggested that strain rate and temperature have great effects on the deformation behavior of rotating band during engraving process.