Industrial Welding Research Articles

Object oriented and distributed software applied to industrial robotic welding

Associating robot manipulators with industrial welding operations is common and maybe one of the most successful applications of industrial robots. Nevertheless, it is far from being a solved technological process, mainly because the welding process is not fully understood but also because robots are still at an early satge of development, being difficult to use and program by regular operators. This is also true for Human Machine Interfaces (HMI), which are not intuitive to use and are therefore unsatisfactory. In this paper we discuss these problems and present a system designed with the double objective of serving our R&D efforts on welding applications, but also our need to assist industrial partners working with welding setups. Frequently industrial partners are not happy with available commercial systems, requiring tailored solutions that could be adapted to several robots and robot controllers. The developed system is explained in some detail, and demonstrated using two test cases which reproduce two situations very common in industry: multi‐layer butt welding (used on big structures requiring very strong welds) and multi‐point fillet welding (used for example on structural pieces for the construction industry).

Open Issues from the 15th International Conference on Manganese

Manganese (Mn) is an essential metal that is required as a cofactor for many enzymes and is necessary for optimal biological function. Mn is abundant in the earth’s crust and is present in soil and well water. Mn is also found in industrial settings, including mining, welding, and battery manufacture. Mn is also present in infant formula, parenteral nutrition, as well as pesticides and gasoline additives. A sufficient amount of Mn is obtained from most diets, and Mn deficiency is exceedingly rare. Excessive exposure to Mn in high doses can result in a condition known as manganism that results in psychological and emotional disturbances and motor symptoms that are reminiscent of Parkinson’s disease, including gait disturbance, tremor, rigidity, and bradykinesia. Treatment for manganism is to remove the patient from Mn exposure, though symptoms are generally irreversible. The effects of exposure to Mn at lower doses are less clear. Little work has been done to evaluate the effects of chronic exposure to subclinical levels of Mn, especially in regard to lifelong exposures and the effects on the aging process. Mn is known to have effects on some of the same mechanistic processes that are altered in aging. This review will describe the general effects of Mn exposure and will focus on how Mn may be related to some of the mechanism of aging: neurogenesis, oxidative stress, and microglial activation and inflammation.

Riction welding of aluminium and plain low carbon steel

The thermal cycle during friction welding is an important factor that significantly affects on the mechanical properties and microstructures in welded joints. The weld heat input has been normally estimated using the torque during friction welding, however most of industrial friction welding machines are not able to measure the torque which cannot be available to use process control.In this paper, the calculation of heat input rate is proposed for friction welding under a new concept for the dissimilar welded joints. This heat input concept, which is solved governing equations combined with high temperature strength, and thermal conduction is successfully expanded into joints by dissimilar materials with large differences of thermal behaviors. It is revealed that mechanical properties are correlated with the proposed heat input rate to dissimilar joints by pure aluminum and plain low carbon steel. Mechanical properties are evaluated by notch tensile strength. This weld heat input rate is also related with intermetallic phase formation that is confirmed in the transmission electron microscope observations.As a conclusion, the optimum welding condition is obtained with increased the heat input rate.1) By using the simple assumptions made in this study, it is possible to obtain the heat input rate, to a certain extent, to predict the mechanical properties of the friction welded joints to dissimilar materials. It is also clarified this proposed heat input rate predicts formation of intermetallic compounds at the weld interface.2) The calculated heat input rate correlates with the tensile strength of the welds. High joint strength is obtained in the case of welds of higher heat input rate.3) Intermetallic phase does not form when friction time is less than 1 second. This is also confirmed from the results of calculation. Intermetallic phase at weld interface is determined as Fe4A13 using diffraction pattern of TEM observation.

Laser beam welding of wrought aluminium alloys

Laser beam welding is now a common manufacturing method for a wide range of steel products from automobiles to razor blades. However, the process has only recently been approved for critical applications involving aluminium alloys, notably in the aerospace and automotive industries. The properties of aluminium alloys influence the interaction between the beam and the material to a far greater extent than for steels. The challenge of developing industrial welding procedures has therefore been considerable. The present review describes the effects of CO2 and Nd–YAG laser beam processing parameters and the properties of the most common wrought aluminium alloys on the characteristics of welded joints. Porosity, solidification cracking, and poor weld bead geometry are shown to be the most frequently encountered imperfections. These can be eliminated through the use of appropriate filler materials, process gases, material preparation, and in some instances, adaptive control systems. Very little work has been reported on the corrosion properties of laser welded aluminium alloys. Experimental processing parameters are presented and compared using an analytical model, which can also be employed for predictive purposes. A number of industrial applications are described. These demonstrate that, for specific alloys, the process is now sufficiently well understood to be approved for high volume production, particularly in the transport industries.

Experimental Study on Combustion and Pollutant Control of Biobriquette

To control pollutant emissions from the combustion of both domestic stoves and small-capacity industrial boilers, an artificial solid fuel called biobriquette has been developed. It is manufactured from a mixture of coal, biomass (sawdust), and desulfurizer under a high compression pressure. In this study, the combustion experiments were performed to elucidate the ignition and combustion characteristics of biobriquette. Comparisons were made between coal briquettes and biobriquettes for their combustion efficiencies and pollutant emissions in existing domestic stoves. Byproduct in the gas welding industry was used as a new desulfurizer in the biobriquette, and its desulfurization characteristics were studied. The experimental result shows that the biobriquette has a lower ignition temperature and a higher combustion efficiency than the coal briquette. The new desulfurizer was found to be more effective in desulfurization than the other two desulfurizers, limestone and scallop shell. It is also found that the biobriquette combustion in domestic stoves gives lower CO2 emission than the normal coal briquette. The developed biobriquette provides a simple, economical, and efficient way for coal utilization and pollutant control in some developing countries.

Numerical modelling of temperature distribution during multipass welding of plates

Welding is a reliable, cost effective, and efficient metal joining process. Manual metal arc welding (MMAW) is a widely used welding process in industry and multipass welding is very frequently used in the MMAW process. The temperature distribution that prevails during multipass welding affects the material microstructure and hardness of the regions near the weld, and the residual stresses that will be present in the material after cooling to room temperature. These changes will consequently affect the performance of the welded joint. In the present work, a computer model based on the control volume method has been developed to predict the temperature distribution during multipass welding of plates using the MMAW process. To validate the computer model, the temperature distribution was measured experimentally in a 12 mm thickness stainless steel weld pad during multipass welding. The welding parameters were used as input data for the computer model. The computer predictions and the experimentally measured temperature distributions agree well.

Occupational health concerns in the welding industry.

The Workplace Safety and Health Branch initiated a proactive study in the welding industry in Manitoba. Eight welding companies participated in this study. Health concerns raised by welders were welders' flash, sore/red/teary eyes, headaches, nosebleeds, and a black mucous discharge from their nasal membrane. Most welders expressed concern regarding excessive smoke levels in the workplace and inadequate ventilation. Types of welding identified were MIG mild steel, MIG stainless steel, and TIG aluminum. Monitoring involved an assessment of noise levels, fume composition, and carbon monoxide and ozone concentrations. Metal analyses were according to National Institute for Occupational Safety and Health (NIOSH) Method 7300. Noise dosimeters used were the Quest model 100 and Micro 14 & 15. Carbon monoxide was monitored using the Gastech Model 4700 and ozone using the AID Portable Ozone Meter Model 560. In Manitoba, a hearing conservation program is required when the equivalent sound exposure level (normalized Lex 8-hr) exceeds 80 dBA-weighted. The American Conference of Governmental Industrial Hygienists' threshold limit value-time weighted average (ACGIH TLV-TWA) for iron is 5.0 mg/m3, manganese is 0.2 mg/m3, carbon monoxide is 25 ppm, and ozone is 0.05 ppm (heavy work), 0.08 ppm (moderate work), and 0.1 ppm (light work). Welders' personal exposures to manganese ranged from 0.01-4.93 mg/m3 (N = 42; AM = 0.5; GM = 0.2; SD +/- 0.9; GSD +/- 3.2) and to iron ranged from 0.04-16.29 mg/m3 (N = 42; AM = 3.0; GM = 1.4; SD +/- 3.5; GSD +/- 2.5). Noise exposures ranged from 79-98 dBA (N = 44; AM = 88.9; GM = 88.8; SD +/- 4.2; GSD +/- 1.0). Carbon monoxide levels were less than 5.0 ppm (at source) and ozone levels varied from 0.4-0.6 ppm (at source). Ventilation upgrades in the workplace were required in most welding shops. Only 7 percent of the welders wore respiratory protection. A hearing conservation program and hearing protection were required at all monitored workplaces.

アルミニウムと炭素鋼の摩擦圧接

The thermal cycle during friction welding is an important factor that significantly affects on the mechanical properties and microstructures in welded joints. The weld heat input has been normally estimated using the torque during friction welding, however most of industrial friction welding machines are not able to measure the torque which cannot be available to use process control.In this paper, the calculation of heat input rate is proposed for friction welding under a new concept for the dissimilar welded joints. This heat input concept, which is solved governing equations combined with high temperature strength, and thermal conduction is successfully expanded into joints by dissimilar materials with large differences of thermal behaviors. It is revealed that mechanical properties are correlated with the proposed heat input rate to dissimilar joints by pure aluminum and plain low carbon steel. Mechanical properties are evaluated by notch tensile strength. This weld heat input rate is also related with intermetallic phase formation that is confirmed in the transmission electron microscope observations.As a conclusion, the optimum welding condition is obtained with increased the heat input rate.1) By using the simple assumptions made in this study, it is possible to obtain the heat input rate, to a certain extent, to predict the mechanical properties of the friction welded joints to dissimilar materials. It is also clarified this proposed heat input rate predicts formation of intermetallic compounds at the weld interface.2) The calculated heat input rate correlates with the tensile strength of the welds. High joint strength is obtained in the case of welds of higher heat input rate.3) Intermetallic phase does not form when friction time is less than 1 second. This is also confirmed from the results of calculation. Intermetallic phase at weld interface is determined as Fe4A13 using diffraction pattern of TEM observation.

Meta opens door to laser based seam welding in auto industry

Meta opens door to laser based seam welding in auto industry

Robot arc welding operations planning with a rotating/tilting positioner

Robotic arc welding has been popular in the welding industry. Major emphasis has been placed on integrating robots with the gas-metal arc welding process due to its predominant use in industry. But, the programming of robots for arc welding is still a time-consuming process. It needs substantial expertise in both robotics and the arc welding process. Thus much effort in robot arc welding programming is concentrated on off-line programming. The Off-Line Programming (OLP) of robotic arc welding requires sophisticated process planning composed of various stages such as robot and positioner motion planning, collision avoidance, weld sequencing, CAD data interfacing, weldseam tracking, and calibration of the robot arm and robotic workcell. However, existing OLP systems do not provide welding operations planning such as weld sequencing and positioner motion planning. Furthermore, they do not consider both workcell productivity and weld quality in the robotic welding cell, which are closely associated with the robot configuration. This is due to unstructured and compound characteristics of welding operations involving the determination of robot welding configurations, weldline clustering and sequencing, and multi-weldline/multipass welding planning. In this paper, we will present a method for robotic arc welding operations planning that can support the robot OLP; namely, a downhand welding algorithm using a rotating and tilting positioner, a robotic welding stability model associated with weld quality and cell productivity, and operations planning procedures for robotic multi-weldline/multi-pass welding.

Current Status of Laser Welding with Wire Feed

Laser welding, currently being actively investigated worldwide, is about to become an important joining method. Traditionally laser welding has always been autogenous. With increased demands of welded joint and industrial applicability laser welding is now more frequently used with wire feed. This paper reviews laser welding with continuous wire feed and illustrates its potential advantages and problems. The current knowledge about basics of the techniques, effects of various variables and phenomena involved are summarized and discussed. It is shown that influence of variables requires understanding of their individual and combined effects. The survey indicates that although laser welding with continuous wire feed is a potential technique for many applications, R&D effort is still required to make the installation economically feasible.

Welding of aluminum: A challenging opportunity for laser technology

The increasing demand for lightweight structures has led to a greater industrial use of aluminum alloys. The application of these materials is handicapped by a lack of productivity and reliability in the joining techniques currently available. The laser welding of aluminum is markedly more difficult than for steel. The difficulties to be solved include the threshold for deep penetration welding, the occurrence of material related defects and seam deficiencies such as cavities and blowholes that discourage production engineers from making greater use of lasers. A theoretical analysis reveals the requirements that have to be fulfilled by laser systems in order to obtain process stability. In comparison to steel greater focusability and shorter wavelengths are needed. An intensity distribution leading to a V-shaped keyhole is also beneficial. The results of this analysis are confirmed by welding results obtained with CO2 and Nd:YAG lasers. An increase in process stability is observed when a dual beam technique or a shorter wavelength laser is applied. In conclusion, the industrial welding of aluminum alloys with appropriate laser systems is a viable option.

Amyotrophic Lateral Sclerosis and Occupational History

To assess the association of a number of occupational and industrial exposures with amyotrophic lateral sclerosis (ALS). A case-control study of ALS cases matched by age and sex to 2 controls each: 1 from a neurologic clinic and 1 from a local community. Exposures were ascertained by questionnaire, and patients were requested before the interview to be to prepared to supply occupational histories. Patients with ALS were enrolled at the University of Minnesota ALS Clinic in Minneapolis. Patients with ALS (n = 25) were from the University of Minnesota ALS clinic, and clinic controls (n = 25) were patients with other neuromuscular diseases from the university's Muscle Disease Clinic, selected on the basis of clinic enrollment date nearest to that of the matched case. Clinic controls were principally patients with myopathies. Community controls (n = 25) were selected from the community using a random-digit-dialing protocol matching on the first 5 digits of the case patient's telephone number. The strongest association with disease was exposure to welding or soldering materials (odds ratio, 5.0) and the welding industry (odds ratio, 5.3). Electric plating showed a high odds ratio of 8 (95% confidence interval, 0.9-72.0), but low statistical significance (P < .07) Several exposures or industries, while not statistically different, showed enough difference that to ignore them might lead to a Type II error, a result of the pilot nature and small sample size. These included paint or pigment manufacturing, the petroleum industry, the printing industry, and shipbuilding. The association with welding, soldering, and the welding industry is strong and suggests a need for further work. This is despite the small numbers studied, thus making most industrial or occupational exposures too limited to draw conclusions or detect associations. Perhaps the most obvious candidate from the welding, soldering exposure for a common toxin would be lead. Other suggestions of risk were seen for paint or pigment manufacture, shipbuilding, electric plating, and the dairy industry. The degree of association for these, while high, is not statistically significant, and suggests that there may be 1 or more environmental toxins common to those industries that need more precise measurement.

Ocular hazards of industrial spot welding.

Any welding process is perceived to be a radiation hazard to the eye. Site visits were made to an automotive assembly plant to assess the levels of optical radiation and other hazards on the production line. Measurements were taken with a scanning spectro-radiometer and optical power and energy meters at operating working distances at spot welding stations where nonrobotic procedures were performed. Ultraviolet (UV) irradiance levels produced while spot welding with electrodes operating at 10 to 15 kA and 10 to 20 V were several orders of magnitude below recommended safety limits for industrial exposure. Flashes were rich in visible light and infrared (IR) radiation, but not at hazardous levels. The principal hazards in manual spot welding with high-current electrodes are high-speed droplets of molten metal produced by the process. These are easily defended against by wraparound polycarbonate eye shields.

Calibration and testing facility for resistance welding current monitors

The lack of uniform and traceable measurement of pulsed high currents (1-200 kA) utilized in the resistance welding process has long been a problem in the welding community. A testing facility utilizing equipment and knowledge gained in the Department of Energy programs is being made available to the American welding industry to solve these problems. Problems in making these measurements traceable to national standards and proposed solutions are presented. Test equipment and methods are described that will be used to evaluate current-sensing coils and weld-current monitors. Comparison of positional errors for various current-sensing coils is presented, including a recently developed, machinable Rogowski coil.

Analytical Study of Hygiene Hazards Involved in Naval Industry Welding Processes

Abstract The metal contents of welding fumes produced at the shipyard Astilleros Espanoles in Puerto Real, Spain, were investigated to assess the hygiene hazards in order to improve health conditions at the factory. Personal and environmental samples were collected on a cellulose or polyvinylchloride filter with the aid of a sampler in compliance with National Institute for Occupational Safety and Health standard methods. Quantitative metal determinations were carried out by flame atomic absorption spectroscopy. A microscopic examination was also achieved to assess shape and size of metal particles. The results obtained for metals and particles were compared with established threshold limit values, and conclusions were drawn according to the type of welding procedure, sampling place, and use of fume extractor.

Investigation of thermal degradation of some adhesives used in the automobile industry by thermal analysis/mass spectrometry and GC-MS

In order to make a direct evaluation of adhesives used in bond welding in the automobile industry we used the so-called “black box” approach. In this case we only know the trade name of the adhesive but not any further information about the raw materials. To obtain information from the thermal behavior of adhesives, we conducted thermoanalytical experiments in an inert atmosphere and coupled thermal analysis/mass spectrometry. Modelling the real situation in bond welding, we made pyrolysis experiments in the German VCI-oven in air. The volatile and semivolatile products of pyrolysis were collected on XAD-resins and after elution, qualitative and quantitative determinations were carried out by gas chromatography/mass spectrometry. According to black box theory, the results (output) were referred to adhesive type used (input). This approach is not restricted to investigating adhesives, but can be applied to all cases where high temperature must be used in the presence of organic materials. The adhesive types investigated were three epoxy resins, one component polyurethane and one butyl-chaoutchouc.

New System to Control Magnetic Arc Blow in Welding

Welding of magnetized steels has long been a problem in the welding industry. When welding is attempted in the presence of a magnetic field, the welding arc becomes deflected. This phenomenon is known as arc blow. Arc blow can cause significant weld defects, it can reduce productivity, and it is frustrating to the welder. Sometimes weld joint magnetism is so great that control methods must be used to produce a satisfactory weld. In 1991, Newport News Shipbuilding (NNS) developed and built six magnetic field negators (patent applied for) for their welding department. Each unit consists of a small hand-carried electromagnet and power supply that operates off any standard 110/120 volt ac power source. The lightweight system is designed to counteract magnetic fields up to 200 milli-tesla (mT) (2000 gauss) across a 13 mm (0.5 in.) weld joint in 25-mm-thick (1 in.) steel. Through laboratory and production testing, the magnetic field negator has demonstrated the ability to neutralize local areas of high residual magnetism, resulting in a considerable reduction of magnetism-related weld quality problems.

3Cr-1Mo-1/4V-Ti-B

Abstract The 3Cr-1Mo-1/4V-Ti-B alloy was developed ato meet requirements for coal liquefaction reactor materials. The alloy is hydrogen resistant at high temperatures and pressures with excellent properties in thick section sizes and at high temperatures. This datasheet provides information on composition, hardness, and tensile properties as well as fracture toughness and creep. It also includes information on heat treating and joining. Filing Code: SA-479. Producer or source: Sumikin Welding Industry.

Nickel-related cancer in welders

During stainless steel (SS) welding, solid aerosols are generated from elemental compounds which are generally considered to be human carcinogens; i.e. compounds of hexavalent chromium (Cr VI) and nickel. Epidemiological studies among groups of SS-welders have indicated that they may carry a higher risk of acquiring lung cancer than mild steel (MS) welders using the same welding techniques. This excess risk has been demonstrated in cohort as well as by case-control studies. The present evidence does not support the view that exposure to SS-welding fumes poses a hazard of cancer at any other site. Exposure to asbestos and smoking are generally major confounders in these studies. The number of SS-welders world-wide seems to be increasing, thus these findings may be of significance to SS-welders and to the welding industry. Despite the information on the possible cancer hazard among SS-welders, current epidemiological data on cancer incidence and mortality do not offer clear evidence to determine whether exposure to nickel or Cr VI compounds constitutes the more important risk factor for lung cancer.