Welding in the '90s.
With explosive growth and rapid developments in both materials and process technology, welding is now being used in the creation of more than 50% of this country's GNP GNP
See: Gross National Product . Yet, as we enter the 90s, a mature welding industry finds itself facing unprecedented opportunities worldwide that will challenge the industry on economic and sociological fronts, as well as in the familiar realm of technology, and require a much higher level of inter-industry cooperation than presently exists.
The keys to future economic survival will be maximizing product efficiency, rapidly assimilating new technologies, and increasing of professionalism throughout the industry. Technical literacy must be stimulated and coalitions formed among welding business and professional groups worldwide.
Towards this end, the American Welding Society The American Welding Society (AWS) is a nonprofit organization dedicated to advancing the science, technology, and application of welding and allied joining and cutting processes, including brazing, soldering, and thermal spraying. (AWS AWS Amazon Web Services
AWS American Welding Society
AWS Advanced Warning System
AWS Advanced Wireless Services
AWS Automatic Weather Station
AWS Alien Workshop (skateboard company)
AWS Austria Wirtschaftsservice GmbH ) has been working to establish working relationships-the exchange of standards, educational texts, and commercial dialog-between AWS and peer societies in other countries. AWS has such agreements with Argentina, Australia, Brazil, Germany, Hungary, Japan, Korea, Mexico, China, Portugal, Singapore, Spain, the United Kingdom, and the USSR USSR: see Union of Soviet Socialist Republics. .
Yet, we still see too little cooperation among standard-setting bodies in the US. Reasons include our entrepreneurial spirit, a lack of coordination with the government, fear of violating FTC FTC
See Federal Trade Commission (FTC). prohibitions on collusion, and in some cases, simply "turf protection."
The need for high tech
Increased emphasis will be placed on welding as a basic manufacturing technology, particularly the use of lightweight, high-strength materials, and higher levels of reliability and quality. To compete, US fabricators will need more automatic and semiautomatic welding for repetitive tasks to reduce costs, manufacturing defects, and environmental hazards.
The trend is to make welding safer and welding machines simpler through the use of microelectronics. Arcs are more stable and current pulses more precise for critical welding jobs. Workcells are becoming more integrated-manipulator, control, positioner, power source, wirefeeder-and cutting equipment more lightweight, portable, and modular. Welding software Welding Software is a general term for welding related software, i.e. applications addressing variety of topics associated with the welding industry, including base metal selection software, filler metal selection, machine welding settings/instructions, weld automation and has become increasingly tailored to specific applications. Advanced materials Advanced Materials is a leading peer-reviewed materials science journal published every two weeks. Advanced Materials includes Communications, Reviews, and Feature Articles from the cutting edge of materials science, including topics in chemistry, physics,
Slowly but surely, advanced materials will provide product differentiation Product Differentiation
A source of competitive advantage that depends on producing some item that is regarded to have unique and valuable characteristics. and increased end-user value on a worldwide basis. New materials will fundamentally change all industry, and joining will become more broadly based than just the welding of metals. Everyone from designer to welder must become more knowledgeable about new materials and more accepting of related new fabrication fabrication (fab´rikā´shn),
n the construction or making of a restoration. technology.
While we don't expect a sudden shift to new materials, the trend towards them will persist-introduced first in relatively low-volume niche areas. Not all issues with these materials are resolved. Designers do not yet have all the necessary information to assure their reliability. Welding equipment manufacturers and fabricators must join to develop the technology to use them. Educators must train everyone from designers to manufacturing engineers to welders to use them also.
Design criteria Noun 1. design criteria - criteria that designers should meet in designing some system or device; "the job specifications summarized the design criteria"
criterion, standard - the ideal in terms of which something can be judged; "they live by the standards of their must be made more realistic and practical. Over-design is too prevalent today because design engineers who do not have a good handle on what welding can do will typically overspecify welded joints. Inordinate concern about product liability makes the problem worse. When everyone in the design chain adds a 5% safety factor, we're soon at a 20% to 30%
The case for sensor control
Using sensors to help automate robotic arc-welding can result in considerable cost reduction, more precise positioning Precise Positioning is a term used to describe techniques to obtain the location of an object to better than a few centimeters of accuracy.
Historically precise positioning was associated with surveying and geodesy. of the torch above the joint, improved weld quality, and reduced fixturing requirements and workpiece-preparation time. More importantly, it drastically reduces the tight-tolerance requirements for the workpiece Noun 1. workpiece - work consisting of a piece of metal being machined
piece of work, work - a product produced or accomplished through the effort or activity or agency of a person or thing; "it is not regarded as one of his more memorable works"; "the symphony was , robot, and fixturing system.
Weld quality problems often occur with larger parts such as car bodies and frames. Repeatability and consistency are common concerns.
There are four choices in welding large structural components:
1. Manual welding which is subject to human error and high per-piece cost.
2. Dedicated welding machinery where joint location must be very accurate and edges need trimming by expensive die sets.
3. Robotic systems where the robot follows a programmed weld path and angle of attack, and workpieces must also be kept within tight tolerances to produce quality welds over long periods of time.
4. Sensor-controlled robotic arc welding where a noncontact measurement sensor on the robot arm guides the welding function. Weld parameters and robot position are adjusted based on these measured values, and seam-location searches and width variations can be easily accommodated.
Of the many types of seam sensors available, only a few can withstand the intense environmental conditions of a welding operation. The sensor must not lose accuracy or resolution in a high-speed environment of welding smoke, electromagnetic interference See EMI. , and changing work surface.
One sensor manufacturer, Selective Electronic Inc (Selcom), Southfield, MI, has 400 seam-finding sensors in use worldwide. Their system includes a noncontact sensor, processing electronics, and controller that is easily integrated into the robotic-control system and programmed through the robot's digital outputs. It is particularly useful for thin-sheet resistance welding Resistance welding
A process in which the heat for producing the weld is generated by the resistance to the flow of current through the parts to be joined. and plasma-arc welding requiring short welds and cycle times. The correct welding parameters are selected within a search time of 1.5 to 2.0 sec in three dimensions or 1 sec in two dimensions. Search accuracy is -0.16" ([+ or -] 0.4 mm), depending on the robot.
Compared to other gaging techniques, optoelectronic sensors are more adaptable to high-speed measurement that is accurate and repeatable. Newer fixed-point laser triangulation triangulation: see geodesy.
The use of two known coordinates to determine the location of a third. Used by ship captains for centuries to navigate on the high seas, triangulation is employed in GPS receivers to pinpoint their current location on earth. designs use solid-state laser diodes instead of gas-laser tubes and can be pulsed at high frequencies (16 or 32 kHz). This is particularly beneficial in background-light discrimination. Sensing of all types of surfaces is not affected by welding sparks.
A typical optical-triangulation sensor consists of an infrared light source, camera/detector, and electronics for signal amplification, light-source control, and measurement calculation. The Selcom Optocator is small in size, light in weight, and insensitive to welding spatter spatter,
n droplets of airborne particulate matter larger than 50 μm that fall to the ground. and fumes fumes
odorous gases and other volatile materials; inhalation of irritating fumes causes coughing and, if sufficiently severe, irreversible pulmonary edema. . As the distance from sensor to surface changes, the position of the focused scatter image on the detector shifts. That shift, through triangulation, directly translates into vertical displacement of the measured surface. Measuring range of the Selcom sensor is 1.25" (32 mm) with a resolution of 0.002" (0.06 mm).
During searches (without the arc actuated), start and stop points of the weld joint are defined in two or three dimensions. During welding, weld parameters can be adjusted for variations in the gap, and, depending on the sensor and robot used, accuracy is typically [+ or -]0.016" ([+ or -]0.4 mm).
A seat-welding installation at Saab Automobile, Kristinehamn, Sweden, chose the Selcom seam finder for these primary reasons:
1. Rapid, accurate, noncontact locating of thin-sheet joints.
2. Measurement unaffected by oil or paint on the part surface.
3. Wider tolerances on mechanical dimensions and workpiece positioning.
4. Easy integration of seam finder and the ABB n. 1. Among weavers, yarn for the warp. Hence,
Noun 1. ABB - an urban hit squad and guerrilla group of the Communist Party in the Philippines; formed in the 1980s robot.
Seam finding is used on the car seat's back rest. A slightly dished dished
2. Slanting toward one another at the bottom. Used of a pair of wheels.
Adj. 1. dished - shaped like a dish or pan
concave - curving inward plate with holes and slots is welded to the seat side frames. Curve of the plate varies from plate to plate and requires a height search.
After the height is defined, lap joints are located and welded. One joint is a series of 0.12" slots that are filled and welded to an underlying part. The edge of each slot is first located, and the controller then offsets the weld program to start in the middle of the slot.