Robot spot welding, often shortened to robot welding, is a welding process that is carried out by programmable mechanized tools or robots. The robot spot welding process is fully automated which enables the handling and welding of a part.
Contrary to popular belief, gas metal arc welding (while often automated) is not classified as robot welding because human intervention is still required during the process, such as preparing the materials to be machined.
Robot welding is often used for arc welding and resistance spot welding in a high-volume production environment, which is why it is a very prevalent welding method used in the automotive industry.
Although it has been a while since robots were invented, robot welding is still a relatively new industrial application of robotics. It had stayed obsolete for some time until automotive industry began to largely incorporate robots. Since then, the welding applications have grown significantly.
The process of robotic spot welding entails applying heat and pressure to weld an area of a part using shaped alloy copper electrodes which relay an electrical current through the work pieces. The material melts, at which point the current is turned off the strain from the electrodes is retained and the molten "nugget" solidifies to form the joint, fusing the parts together.
The electric current, which is transferred to the work piece by copper alloy electrodes, produces the welding heat. Copper is used for the electrodes because, compared to most other metals, it has a high thermal conductivity and low electrical resistance, meaning that the heat is produced preferentially in the work parts instead of the electrodes.
In the current era, automation is very essential technology used to greatly reduce human intervention in production of goods and services to yield maximum efficiency. To achieve automation, robotic machineries have gradually been implemented to replace human labor for operations that are repetitive. A perfect example of the emerging trend is the application of industrial robots in spot welding which is used in high production applications mostly utilized in automotive industry – an industry that requires massive, repeated productions.
Robotic welding is essential in the automotive industry because of the complex welding profile of the parts and the difficulty in handling an extremely heavy part manually. Due to the higher cost of industrial robots and robotic welding setup, robotic spot welding was mostly used in large scaled industries, if not automobile. But to meet new challenges and stay competitive globally, medium or small industries can no longer concede to look for ways to automate manual operations even if it means to incur substantial upfront expensive. Implementing robotic spot welding to maximize efficiency and reduce labor cost for become necessary for some industries.
The primary benefit of robotic welding is that it requires very little, if any, human oversight, thereby enhancing the efficiency, accuracy and safety of the welding process. Another advantage is that the welding robots can be programmed to be either partially or fully automated depending on the production and application, giving the operators the flexibility to cope with production scheme changes.
Robotic spot welding differs from machine assisted or manual welding, which relies heavily on human supervision, as well as incurring lots of labor cost and potential errors. Conversely, robotic spot welding provides much faster and more efficient welding process as the technology continues to develop. They are able to undertake repeated operations while retaining the required accuracy, as well as ensuring maximum output compared to manual welding. This in turn results in a significantly increase in the profit margin compared to manual welding.
You can never go wrong welding steel because of its thermal conductivity and higher electrical resistance, with low carbon steel being the most prevalent for spot welding. High carbon steels on the other hand are not ideal because they are subject to cracking or poor fracture toughness in the welds as brittle microstructures tend to be formed.
Moreover, zinc coated steel requires higher welding currents by a tad bit as opposed to other uncoated steels. With zinc alloys, copper electrodes can degrade the surface rapidly which ultimately compromise the weld quality. Therefore, keep in mind that electrodes must be exchanged frequently when you are spot welding zinc coated steels.
Another popular material used for spot welding include stainless steels, titanium and nickel alloys. While the thermal conductivity and electrical resistance of aluminum is similar to that of copper, the melting point is lower for aluminum, which ensures that welding is possible. However very high current levels need to be used when welding aluminum due to its low resistance.
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