Industrial Welding Research Articles

Improving Changeover Time: A Tailored SMED Approach for Welding Cells

Short changeover times have always been critical in manufacturing business. Set-up duration reduction initiatives have been associated with Shingós ‘Single Minute Exchange of Die’ (SMED) method. Although a great number of companies have initiated SMED, some failed on implementation. The main reason is that strict application of Shingós SMED methodology is not the most efficient way to reduce set-up times in all situations. In the present study a tailored methodology is presented that has been developed specifically for an automotive supplier. The validation of the proposed method was done through implementation on an industrial welding cell for a period of four months. The main finding is that in addition to SMED tailored methodology, appropriate strategy definition and preparatory activities are key enablers for success. That includes project targets and timescale definition, selection of the appropriate team and coordinator, allocation of specific roles and responsibilities to each team member, training of team and shop floor staff on the new methodology and changeover standards. By implementing the new tailored SMED improvement programme, the company achieved 33% reduction on changeover time.

Analysis of Image Segmentation for Radiographic Images

Digital image processing is used to identify regions in an image by using various segmentation methods. This paper gives a brief account on five of the different segmentation techniques namely region growing, watershed, thresholding, split and merge, k-means clustering methods highlighting the advantages as well as disadvantages of each of these methods. A modification of traditional region growing segmentation method is presented which automatically selects the seed points and grows the regions until all the regions in the image are segmented. The results of segmentation methods presented in the paper are not dependent on the kind of image to be segmented and these methods are used in segmenting industrial radiographic weld images in which several defects like porosity, lack of fusion, slag line, incomplete penetrations, and wormholes occur. The methods are evaluated on various types of images and efficiency of these methods in the detection of several weld defects is presented along with the experimental results. The evaluation of performance of these different segmentation methods on sample images is done on the basis of subjective criteria and conclusions are achieved. These methods are used to detect the flaws in an object by identifying the flawed region in the image. Due to this ability of region detection, it finds various applications in medical imaging, optical character recognition, computer vision, remote sensing, mobile robots and industrial radiography. Keywords: Image segmentation, thresholding, region growing, watershed, split and merge, k-means clustering

통계를 이용한 국내 용접산업 현황 분석 (III)

통계를 이용한 국내 용접산업 현황 분석 (III)

Knowledge modelling for laser beam welding in the aircraft industry

This paper presents a knowledge model of the laser beam welding (LBW) in the aircraft industry, which is developed through the utilisation of integration definition for function modelling and concept mapping. The developed knowledge model has been captured in the form of rules and recommendations, which is commonly used as guidelines in this field, and represented with unified modelling language. The LBW component development comprises four key stages, namely, structure design, process planning, fixture fabrication and component fabrication. This has been achieved through the adoption of a three-phase qualitative research methodology: data collection and analysis, knowledge model development and validation. The captured knowledge in the form of rules and recommendations has developed an understanding of the LBW in the aircraft industry and improved the structure design and process planning from joint type selection, structure dimension definition and process parameter optimisation, etc. A prototype handbook has been developed based on skin–stringer connection of aircraft fuselage to guide designers and engineers directly in developing laser beam-welded fuselage panels. The procedure of knowledge modelling for the LBW as well as the methods and tools adopted can be applied to other processes. The developed knowledge model has been validated through a case study.

Focus on International and Regional Standards Devoted to Health, Safety and Environment

The complexity of welding fabrication activities requires an in-depth knowledge of all the involved aspects, including the industrial best practices. In this view Standards and Technical Reports are the most recognized documents developed by standardization committees and IIW, together representing the welding community. The scope of this paper is to focus on international and regional standards which may help the welding industry in managing the aspects of Health, Safety and Environment.

Temperature and emissivity determination of liquid steel S235

Temperature determination of liquid metals is difficult but a necessary tool for improving materials and processes such as arc welding in the metal-working industry. A method to determine the surface temperature of the weld pool is described. A TIG welding process and absolute calibrated optical emission spectroscopy are used. This method is combined with high-speed photography. 2D temperature profiles are obtained. The emissivity of the radiating surface has an important influence on the temperature determination. A temperature dependent emissivity for liquid steel is given for the spectral region between 650 and 850 nm.

In situ droplet surface tension and viscosity measurements in gas metal arc welding

In this paper, we present an adaptation of a drop oscillation technique that enables in situ measurements of thermophysical properties of an industrial pulsed gas metal arc welding (GMAW) process. Surface tension, viscosity, density and temperature were derived expanding the portfolio of existing methods and previously published measurements of surface tension in pulsed GMAW. Natural oscillations of pure liquid iron droplets are recorded during the material transfer with a high-speed camera. Frame rates up to 30 000 fps were utilized to visualize iron droplet oscillations which were in the low kHz range. Image processing algorithms were employed for edge contour extraction of the droplets and to derive parameters such as oscillation frequencies and damping rates along different dimensions of the droplet. Accurate surface tension measurements were achieved incorporating the effect of temperature on density. These are compared with a second method that has been developed to accurately determine the mass of droplets produced during the GMAW process which enables precise surface tension measurements with accuracies up to 1% and permits the study of thermophysical properties also for metals whose density highly depends on temperature. Thermophysical properties of pure liquid iron droplets formed by a wire with 1.2 mm diameter were investigated in a pulsed GMAW process with a base current of 100 A and a pulse current of 600 A. Surface tension and viscosity of a sample droplet were 1.83 ± 0.02 N m−1 and 2.9 ± 0.3 mPa s, respectively. The corresponding droplet temperature and density are 2040 ± 50 K and 6830 ± 50 kg m−3, respectively.

Operation of a Fuzzy Controlled Half-Bridge DC-Converter as a Welding Current-Source

A new Fuzzy controlled welding machine (FCWM) current source is introduced in this paper and the results of the new control method are explained. The Fuzzy controller is applied to the welding machine to improve some problems of welding process. The new intelligent controller guaranties a constant current during welding to improve welding quality. It also provides some features such as hot-start and anti-stuck function and a standby mode for energy saving. The effectiveness of this intelligent welding machine was proven by the experimental results and durable test. The results show that designed FCWM can be used in mobile welding industries.

Operation of a Fuzzy Controlled Half-Bridge DC-Converter as a Welding Current-Source

In This paper a new Fuzzy Controlled Welding current source is introduced and the results of the new control method are explained. The Fuzzy controller is applied to the welding machine to improve some problems of welding process. The new intelligent controller guaranties a constant current during welding to improve welding quality. It also provides some features such as hot-start and anti-stuck function and a standby mode for energy saving. The effectiveness of this intelligent welding machine was proven by the experimental results and durable test. The results show that designed FCWM (Fuzzy Controlled Welding Machine) can be used in mobile welding industries.

Deltaspot as an innovative method of resistance spot welding

Resistance spot welding has established itself across a wide range of industries as a cost-effective method for joining steel sheets. In modern vehicle manufacturing in particular, steel sheets of varying strengths, quality and surface treatment need to be joined. One of the problems of resistance spot welding in the automotive industry is the lifetime of welding electrode tips. The new innovative method of resistance spot welding DeltaSpot should solve this problem by using the special process tape between welding electrodes and joining materials. The paper describes the principle of DeltaSpot welding method and evaluates the properties of DeltaSpot joints made by combination of galvanized steel sheets DX51D+Z (a0 = 0.9 mm) and RA-K 40/70+Z100MBO (a0 = 0.77 mm). The basic mechanical properties of welded joints were evaluated. Some samples were prepared for metallographic analysis where the influence of the welding parameters on the structure of welded joint was observed. The properties of DeltaSpot joint were compared to the properties of standard resistance spot joints.

Kinematic-Kinetic-Rigidity Evaluation of a Six Axis Robot Performing a Task

Six axis serial robots of different sizes are widely used for pick and place, welding and various other operations in industry. Developments in mechatronics, which is the synergistic integration of mechanism, electronics and computer control to achieve a functional system, offer effective solutions for the design of such robots. The integrated analysis of robots is usually used in the design stage. In this study, it is offered that the integrated analysis of robots can also be used at the application stage. SolidWorks, CosmosMotion and ABAQUS programs are used with an integrated approach. Integration software (IS) is developed in Visual Basic by using the application programming interface (API) capabilities of these programs. An ABB-IRB1400 industrial robot is considered for the study. Different trajectories are considered. Each task is first evaluated by a kinematic analysis. If the task is out of the workspace, then the task is cancelled. This evaluation can also be done by robot programs like Robot Studio. It is proposed that the task must be evaluated by considering the limits for velocities, motor actuation torques, reaction forces, natural frequencies, displacements and stresses due to the flexibility. The evaluation is done using kinematic, kinetic and rigidity evaluation charts. The approach given in this work can be used for the optimal usage of robots.

Software for PID Design: Benefits and Pitfalls

The most common PID design methods in industry are based on formulas. This article will present some major advantages of instead using the power of computer based softwares for PID controller design. The Matlab based software used in this work was developed in 2007 and derives robust, IAE minimizing, PID controllers. The experiences of using this software are collected in this article and include control signal activity limitation due to measurement noise, controller design on an industrial Friction Stir Welding process and fast controller design for large batches of processes. It is shown that the properties of the software make it suitable for design of PID controllers and in PID research. There are, however, some possible design pitfalls that the user needs to be aware of. Some of these are presented as well.

Modelling of the Heat Flux Density Distribution for Laser Beam Welding

Great interest of the laser beam welding in industry is a new theoretical task, making planning the welding procedure specification and the quality control of welded joints easier. Estimating and calculating the dimensions of a weld pool and temperature distribution near weld mainly concern heat source modelling. In the presented work calculations of welding pool shape and thermal field for cylindrical-powered-normally model of heat source have been presented. Parameters of the model of heat source and weld pool geometry were determined using analytical-numerical calculations. The results of numerical calculations were compared with the experimental data for butt joint made by CO2 laser beam. Comparable results have been observed. Practical recommendations for assumptions of model parameters - the flux density energy distribution of the heat source in case of calculations of the thermal field in the vicinity of a weld pool are given.

Fume transports in a high rise industrial welding hall with displacement ventilation system and individual ventilation units

Abstract To protect any person from exposure to the toxic and cancerous particles, welding fumes should be removed from region of respiration. In the present work, displacement ventilation system has been established within a high rise-welding hall, where welding processes cause very high welding fume emissions which flow in a thermal up-current from above the welding point to the ceiling. Numerical simulations on the air flow, thermal flow and pollutants have been conducted, showing that displacement ventilation can effectively remove the airborne pollutants from the respiration region and produce the suitable thermal stratification within the large scale industrial building space. Additionally, the personalized ventilation unit is adopted to deliver fresh air to the breathing zone. The spatial distribution of airborne pollutants is affected by the altitude of personalized ventilation annulus, which is numerically investigated to enhance the overall performance of the displacement ventilation and personalized ventilation units. Finally, on site measurements presented in this paper demonstrate the above mentioned numerical investigations. This research will be significant for the ventilation in high rise industrial buildings.

Physical and Cognitive Effects of Virtual Reality Integrated Training

The objective of this study was to evaluate the cognitive and physical impact of virtual reality (VR) integrated training versus traditional training methods in the domain of weld training. Weld training is very important in various industries and represents a complex skill set appropriate for advanced training intervention. As such, there has been a long search for the most successful and most cost-effective method for training new welders. Participants in this study were randomly assigned to one of two separate training courses taught by sanctioned American Welding Society certified welding instructors; the duration of each course was 2 weeks. After completing the training for a specific weld type, participants were given the opportunity to test for the corresponding certification. Participants were evaluated in terms of their cognitive and physical parameters, total training time exposure, and welding certification awards earned. Each of the four weld types taught in this study represented distinct levels of difficulty and required the development of specialized knowledge and skills. This study demonstrated that participants in the VR integrated training group (VR50) performed as well as, and in some cases, significantly outperformed, the traditional welding (TW) training group.The VR50 group was found to have a 41.6% increase in overall certifications earned compared with the TW group. VR technology is a valuable tool for the production of skilled welders in a shorter time and often with more highly developed skills than their traditionally trained counterparts. These findings strongly support the use ofVR integrated training in the welding industry.

Estimativa da produtividade em soldagem pelo Método de Monte Carlo

O objetivo deste artigo é o de analisar a viabilidade da utilização do método de Monte Carlo para estimar a produtividade na soldagem de tubulações industriais de aço carbono com base em amostras pequenas. O estudo foi realizado através de uma análise de uma amostra de referência contendo dados de produtividade de 160 juntas soldadas pelo processo Eletrodo Revestido na REDUC (refinaria de Duque de Caxias), utilizando o software ControlTub 5.3. A partir desses dados foram retiradas de forma aleatória, amostras com, respectivamente, 10, 15 e 20 elementos e executadas simulações pelo método de Monte Carlo. Comparando-se os resultados da amostra com 160 elementos e os dados gerados por simulação se observa que bons resultados podem ser obtidos usando o método de Monte Carlo para estimativa da produtividade da soldagem. Por outro lado, na indústria da construção brasileira o valor da média de produtividade é normalmente usado como um indicador de produtividade e é baseado em dados históricos de outros projetos coletados e avaliados somente após a conclusão do projeto, o que é uma limitação. Este artigo apresenta uma ferramenta para avaliação da execução em tempo real, permitindo ajustes nas estimativas e monitoramento de produtividade durante o empreendimento. Da mesma forma, em licitações, orçamentos e estimativas de prazo, a utilização desta técnica permite a adoção de outras estimativas diferentes da produtividade média, que é comumente usada e como alternativa, se sugerem três critérios: produtividade otimista, média e pessimista.

Core Competencies in Vocational Welder Worker: Based on Thai Welding Industry Participator Perceptions

A core competency facilitates the identification of training needs and guides the design of a professional development program. Thus, this research was to explore and examine the core competencies in vocational welder worker based on Thai welding industry participator perceptions. To synthesize core competencies first used the focus group technique with 17 experts to identify their perspectives on core competencies in vocational welder worker. After that competencies questionnaire survey was developed to collect data from a participator sample consist of , 206 welding industry participators. Research methods were applied to collect quantitative data using questionnaires, forms, interviews, discussion groups and workshops. The resulting analysis revealed that the main elements of the competencies in vocational welder worker could be divided into three core competencies categories, namely: 1) The knowledge and skills generally: Basic skills and Information technology skills 2) The knowledge and skills specific: Process of connection and control, Welding process design, Metal structuring, The selection of proper welding process, Welding control, Inspection and testing process piece, Drawing and design product, Handmade sheet metal product, Produce and control manufacturing, and Pipe installation 3) The attitude: Personalities and human relation.

DESIGN OF A PORTABLE ELECTROTHERMAL VAPORIZATION FLAME ATOMIC EMISSION SPECTROMETRY DEVICE FOR FIELD ANALYSIS

A nontraditional, portable flame atomic emission spectrometry (FAES) device has been constructed using a welding industry metal cutting torch as the flame source with a tungsten coil electrothermal vaporization device for sample introduction. Twenty-microliter sample aliquots were pipetted onto a commercially available tungsten filament, and a home-written Visual Basic program was used to automatically dry and atomize the sample. The sample was then transported into the heart of the air-acetylene flame, where it was excited, and the resulting emission signal was focused onto the entrance of a miniature charge coupled device spectrometer. Figures of merit were determined for five alkaline and alkali earth metals of biological and environmental significance. Limits of detection were, on average, 100 times lower than those for traditional flame emission spectrometers. The capabilities of this portable device make it an ideal tool for biological field analysis, particularly in areas where traditional laboratories are inaccessible.

Virtual welding equipment for simulation of GMAW processes with integration of power source regulation

A two dimensional transient numerical analysis and computational module for simulation of electrical and thermal characteristics during electrode melting and metal transfer involved in Gas-Metal-Arc-Welding (GMAW) processes is presented. Solution of non-linear transient heat transfer equation is carried out using a control volume finite difference technique. The computational module also includes controlling and regulation algorithms of industrial welding power sources. The simulation results are the current and voltage waveforms, mean voltage drops at different parts of circuit, total electric power, cathode, anode and arc powers and arc length. We describe application of the model for normal process (constant voltage) and for pulsed processes with U/I and I/I-modulation modes. The comparisons with experimental waveforms of current and voltage show that the model predicts current, voltage and electric power with a high accuracy. The model is used in simulation package SimWeld for calculation of heat flux into the work-piece and the weld seam formation. From the calculated heat flux and weld pool sizes, an equivalent volumetric heat source according to Goldak model, can be generated. The method was implemented and investigated with the simulation software SimWeld developed by the ISF at RWTH Aachen University.

Modelling of hybrid laser–GMA welding: review and challenges

Hybrid welding, which is the integration of laser beam welding (LBW) and gas metal arc welding (GMAW), may minimise the disadvantages while retaining the advantages for each of the two welding technologies and, hence, has recently received increasing interest in the welding industry. However, the hybrid welding involves very complex transport phenomena which are inherited from each of LBW and GMAW and their interactions. The development of hybrid welding has been based on the trial and error procedure and so far rather limited numerical modelling on hybrid welding is available. This paper presents an up to date literature review on modelling of the hybrid welding including LBW and GMAW. Issues and challenges for a comprehensive hybrid welding model are discussed. With the advances of numerical techniques and computers, a comprehensive hybrid welding model can be developed as a useful tool for determining key process parameters and helping the elimination/reduction of possible weld defects.