Surface Engraving Research Articles

Controlling the Surface Friction of Rotating Rods by Laser Surface Engraving

Controlling the Surface Friction of Rotating Rods by Laser Surface Engraving

Plasma–induced rapid crystallization and surface engraving of amorphous TiOx(OH)y to enhance adsorption and photocatalytic activity

Herein, we highlight a facile, green, and controlled technique commonly known as plasma-liquid interaction for crystal growth, defect engineering, and surface modification of amorphous titanium oxide. Using a novel two-step procedure combining hydrolysis and plasma treatment, we have fabricated defect-enriched anatase TiO2 powder. Rapid crystallization of amorphous titanium oxide is observed due to the interaction of plasma-generated reactive species with the solvated material. However, prolonged treatment time decreases the material's crystallinity due to excess generation of oxygen vacancy defects (OVD) in the TiO2 lattice. The plasma treatment also engraves the material’s surface forming the porous structure, increasing the specific surface area to ∼46 %. At a higher treatment time, TiO2 nanoparticles are grown on the material’s surface. The dye adsorption of the material is quite rapid, and the performance depends on the material’s surface condition. This rapid adsorption speeds up the photo-degradation performance (up to ∼96 %) of the material. The presence of OVD increases the photocatalytic activity of the material. However, an excess amount of OVD quenches the activity. A comparative study between ambient air and argon plasma-assisted material modification for optimized adsorption and photocatalytic performance has been carried out.

Experimental investigation of laser engraving quality on paper.

Laser engraving technology is a type of laser processing technology, widely used for product coding, marking, and so on. A large amount of research has reported the results of metal surface engraving; however, few research results, to the best of our knowledge, have provided theoretical support for the application of paper packaging laser engraving. In this paper, the quality of paper laser engraving is investigated by experimental methods. First, various phenomena appearing in paper carving were studied, including plant fiber burning, charcoal, and edge marks; second, the main factors affecting the quality of laser engraving are researched, and the influence of laser intensity and the preset width of carving marks on the engraving quality are discussed. The results show that the engraving precision is the best when the laser power is 11 W and the preset width is small (0.26 mm). Finally, the laser engraving precision of UV coated paper is studied, and the effect of UV material melting and secondary crystallization on engraving the quality of paper laser engraving quality is discussed. When the laser power is small, the maximum and minimum values of UV film melting and secondary crystallization engraving trace are relatively small as well; further, when the laser power increases, the maximum width of engraving is basically consistent with the preset width, and the precision of laser engraving is optimal.

Machine Learning Based Prognostics of Fatigue Crack Growth in Notch Pre-cracked Aluminum 7075-T6 Rivet Hole

Constant stress amplitude fatigue tests were conducted on the notch pre-cracked Aluminum 7075-T6 rivet hole dog-bone coupons. Monitoring of visible surface crack length by special surface engraving using digital microscope images and by ultrasonic sensors signals was carried out to yield fatigue crack length measurements in relation to number of fatigue cycles applied. The experimental results provide ultrasonic sensor validation for fatigue crack length measurements. Fracto-graphic examination of failed fatigue surfaces has provided further confirmation of notch pre-crack length, crack initiation process, and crack growth marker bands. These experimental inputs were used in NASGRO and AFGROW software fatigue crack growth simulations. The simulation results did not match the crack initiation fatigue life measured by experiments. However, there was good agreement with crack growth simulations of larger cracks. Hence, we plan to develop a machine learning application that will learn the fatigue crack initiation and crack growth processes from data obtained from our own experiments and other fatigue data available from AFGROW databases. Nonlinear AutoRegressive models with eXogenous input (NARX) artificial neural network were used to predict crack growth longer than 5.0-mm. Particle filtering modeling with Bayesian updating was applied to these experimental data for prognostics of fatigue crack growth. A concept design and preliminary implementation results will be presented.

An Engraving Character Recognition System Based on Machine Vision

In order to solve the problem of low efficiency, low quality and false detection of metal surface engraving character detection, we proposed a kind of engraving character recognition system based on machine vision. This system can identify and detect through the image acquisition of engraving area, and a series of mathematical and morphological treatments of binary image. It can extract the contour using optimized Laplace edge detection operator and combining with the convexity characteristic of engraved words. The system successfully carried out the experiment of engraving character recognition and it can detect the character recognition with high efficiency and high qualified rate. It has realized the automation of engraving character recognition test production line, and it has certain application value and promotion significance.

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.

Color Fading of Indigo-Dyed Cotton Denim Fabric by Laser

Laser allows short-time surface engraving of the patterns of desired variety, size, and intensity on a wide range of textile surfaces with precision and without much damaging the texture of the materials. The laser application in textile material has been applied possible to make denim fabric looked faded and worn out without the use chemical process. In this study, laser was applied on the denim fabric in order to evaluate its effect on fabric shade. The laser power density increased in response to the increase in the level of pixel time and resolution. Under the effect of high laser power density, a paler surface appearance was noted in the denim fabrics and the K/Ssum values indicated that the amount of dye on denim fabric was decreased significantly.

Comparison of Picosecond and Femtosecond Laser Ablation for Surface Engraving of Metals and Semiconductors

Pico and femtosecond lasers present a growing interest for industrials applications such as surface structuring [1] or thin film selective ablation [2]. Indeed, they combine the unique capacity to process any type of material (dielectrics, semiconductors, metals) with an outstanding precision and a reduced affected zone. We report on results about surface engraving of metals (Al, Cu, Mo, Ni), semiconductor (Si) and polymer (PC) using a picosecond thin disk Yb:YAG-amplifier. The pulse duration of this source can be changed using two different configurations: direct amplification of a 34ps-oscillator on one hand, and 1ps-chirped pulse amplification (CPA) scheme on the other hand. The results obtained with this thin disk laser are compared to ones achieved with two commercial femtosecond lasers respectively based on Yb-doped crystals and fibers, and operating at similar output power levels (up to 15Watt).

Laser Marking in Digital Encoding of Surfaces

In this work we consider some laser based methods and technologies for surface engraving and layered marking of opaque and transparent materials. Based on that, physical object surface and sub-surface layers can be enhanced with digital codes for augmented security and more advanced human-computer interactions. Laser procedures for creating digitally encoded layers in various materials are investigated and one of the mechanisms of laser-induced formation of marks (micro-cracks) in transparent materials is discussed in more details.