Research On Laser Direct Marking 2D-Barcodes Process On Titanium Alloy Substrates

Manufacturers see an increasing need to address full life cycle traceability with rapid development of manufacturing informatization.Marking parts with machine-readable codes allows for a part to be tracked throughout the manufacturing process and the supply chain.Laser based direct part marking of Data Matrix codes is the best choice to achieve this aim.Because of the diversity of laser processing parameters and substrate materials,the biggest challenge in the application of laser based direct part marking technique is to consistently produce high quality machine-readable barcodes.The widely used titanium alloy in industry is selected as the experimental material.The feasibility of laser direct marking Data Matrix barcodes was firstly studied.The relashionship between laser processing parameters and the geometric features and readability of laser marked Data Matrix barcodes have been investigated to improve the quality of barcodes and determine the laser parameters.The objective is to consistently produce machine-readable 2D barcodes with small damage to the substrate.The research results are of great significance and application value to the development of enterprise informatization.The following studies have been carried out.(1)The technical requirements of marking 2D barcodes were analyzed,and then the experimental apparatus was set up.The feasibility of laser direct marking Data Matrix barcodes onto titanium alloy substrates had been studied.The experiment was carried out on a thin plate of 2mm thick.The microstructure of the laser marked area was measured by using the environmental scanning electron microscope and X-ray diffractometer.Results show that there is neither deformation nor microcracks within the titanium alloy substrate.This indicates that the laser does not have a destructive effect on the substrate.The conclusion lays the foundation for the following studies.(2)Laser direct marking technology was studied to improve the quality of Data Matrix barcodes.The quality assessment method of laser marked Data Matrix barcodes was proposed.The computational models of symbol contrat,marking depth and surface roughness of laser marked Data Matrix code were given.The six laser parameters(i.e.effective vector step,delay between the effective vector step,Q-switch frequency,Q release time,pumping current,and laser line spacing)were selected to carry out single factor experiments by analyzing the function and correlation of laser parameters.The effects of these laser parameters on the quality and microcosmic quality of the resulting 2D barcodes were studied.The relationship between the laser processing parameters and the geometric features and quality of the resulting marks were analyzed.Single-factor analysis of variance(ANOVA)results showed that the four laser marking parameters(i.e.pumping current,effective vector step,Q-switch frequency,and laser line spacing)had a statistically significant effect on the contrasts of laser marked Data Matrix symbols.(3)Based on the interaction between laser and material,the Taguchi orthogonal experiments were carried out to improve the quality of laser marked Data Matrix barcodes.The ratio of signal to noise for Data Matrix symbol contrast and multi-factor ANOVA were carried out.The optimal combination levels of laser parameters and the statistical significance of each parameter on the quality of Data Matrix barcodes were determined.The laser processing parameters optimization of was carried out based on the neural network and intelligent optimization method,and the two optimization results were analyzed.The relationship between the geometric features and symbol contrast of the resulting marks were analyzed.Thus laser marked 2D barcodes of high quality could be guaranteed.(4)The quality prediction modeling of laser direct marking on titanium alloy substrate was studied.The multivariate nonlinear regression models were established based on stepwise regression analysis.The significance of the three regression models was tested by using variance analysis method.The partial regression coefficients were tested by t-test and the fitting effect of the three regression models was evaluated.These three models were also verified using additional experimental conditions.In addition,20 sets of parameters were selected from the recommended optimal parameters to test the prediction models.This can further improve the quality of Data Matrix symbols and surface finish of laser marked area.Thus the machine reading efficiency of barcodes in industry was enhanced and the development of manufacturing informatization was promoted.The results also provide references for laser direct marking of other materials.(5)The laser color marking technique on titanium alloy substrates was studied.The calculation model of chromacity coefficient was derived based on theory of interference.The chromacity of the oxide film on the surface of titanium alloy is calculated and experimentally verified.Based on the chromacity coefficient,the parameter range of laser coloring on titanium alloy surface is calculated.Then the influence of laser parameters on the resulting colors was studied.The environmental scanning electron microscope(ESEM)and X-ray diffractometer(XRD)were utilized to analyze the blue pattern.The repeatability of laser induced colors was studied and the laser color marking technology was applied to the marking field of Data Matrix barcodes on titanium alloy substrates.The color Data Matrix barcodes were successfully marked and they can meet the industrial reading requirements.The color marking method is not only artistic,but also has small damage to the surface,which guarantees the integrity of the parts to the greatest extent.Therefore,the laser color marking technique has a good application prospect.