Automated Resistance Welder: An Evolution

Posted on Jan 15, 2021

Automated Resistance Welder

An automated resistance welder, essentially a type of resistance/spot welding robot, is what embodies the automated resistance welding process. As automation and robotic technology, as well as the quality of equipment, continue to evolve, manufacturers are now capable of making state-of-the-art resistance welding robotics that provides a great many benefits, such as the fact that spot welding can now be done in smaller physical spaces and the improved compatibility by which other parts of the assembly process can be easily integrated.

If you don't already know resistance welding (commonly known as spot welding), it is essentially the joining of metals by applying pressure and conveying current through the metal ends to be joined for a length of time, typically performed by a dedicated spot welding machine. But what we want to focus on today is this welding technique in association with automation systems. 

With automation systems becoming more prevalent in recent years, resistance welding has become an excellent candidate for robotics and automation. This advancement is often referred to as automated resistance welding, the welding application of which mainly lies in automotive and vehicle assembly for body components and frames, where thousands of welds often take place.
 

What Is an Automated Resistance Welder?

Following the above, an automated resistance welder, which is essentially a type of resistance/spot welding robot, is what embodies the automated resistance welding process. As automation and robotic technology, as well as the quality of equipment, continue to evolve, manufacturers are now capable of making state-of-the-art resistance welding robotics that provides a great many benefits, such as the fact that spot welding can now be done in smaller physical spaces and the improved compatibility by which other parts of the assembly process can be easily integrated. The result is often consistent and yields repeatable welding output with high levels of quality in less time compared with conventional resistance welding machines.
 

:: Read More: Read this to Understand Resistance Spot Welding!

Features and Considerations

So what features can we expect from an automated welding robot and what should be considered?
 

Arm Reach

A resistance welding robot has robotic arms to perform the welding process. The arms must be able to assume any needed position so that the weld gun can carry out the welding tasks.
 

Welding Guns

Following the above, spot welding guns of a resistance welding robot can weigh over 100 pounds, so not only should the reach of the arm be considered, but manufacturers would have to make sure that the arms are able to support the immense weight safely. The weight of cables, hoses, and other components have to be taken into consideration as well.
 

Clamping Pressure

The clamping pressure of a resistance welding robot affects the weld quality as well as limits distortion around the HAZ. This is controlled by a servo-controlled gun using a motor to open, close, and apply consistent pressure for the electrode clamp.
 

Articulation and Multi-axis Motion

Robotic arms must have several joints that can engage in a range of motions to perform a variety of welds. The arms should be able to bend and rotate freely and to maximize the reach, some units may even have up to seven axes of motion.
 

Power Supply

The power supply is one of the core components of a resistance welding robot. It conveys the predefined current to the electrodes to heat, melts the pieces, and produces the weld nugget.
 

Time and Speed Settings

An automated unit generally has some kind of timer feature, which determines the duration of electrode clamping to create a nugget of the desired size precisely. Speed settings on the other hand determine how fast an arm can move from one motion to the other.
 

Fixture Design

The fixture is another essential component that contributes to the weld quality. It must be able to position the components to be welded accurately, allowing all sides of the workpiece for electrode contacts.
 

What Makes an Automated Welder Superior?

Now the purpose of a robotic and manual welding machine is the same, which is to join two workpieces with a combination of heat and pressure. But what makes the automated unit superior? Robots minimize the need for human intervention while guiding the entire process without manual steps. Manual units on the other require additional manpower to load and unload the metal workpieces before and after welding. Although both the robotic and manual processes have their own strengths and weaknesses, for the remainder of this section we’ll specifically discuss the advantage of the automated unit.

To begin, automated welding systems are characterized by superb repeatability and consistency that even highly skilled operators can’t match. This leads better weld quality as automated operations can consistently deliver optimal and reliable welding results. The control system also ensures that all welds meet the predetermined requirement prior to production.

Another notable benefit is the higher output. Humans have yet to be able to compete with robots in terms of work speed, meaning that robots will always be able to work faster and longer during robotic welding processes. Even if the manual alternatives are able to achieve speed, it is often at the expense of accuracy or quality. That being said, human workers are often minimized or opted out in a highly automated setting, which leads to another major benefit – reduced labor cost. Human labor is generally one of the most expensive aspects of production. Compared to a manual-oriented setting in which you have to stuff human labor to undertake and oversee the welding process, a fully automated or semi-automated process would only require a limited number of trained welders to supervise the process, thereby saving substantial costs.
 

The Importance of Welding Preparation

With the many wonderful benefits of automated resistance welders we described above, do keep in mind that they do not justify poor preparation for the spot welding process. The quality of the components going into a welding station and how well you set up the process will dictate the quality of the finished part. This is in fact one major downside of an automated (especially unsupervised) process because even a fraction of an error on each part slowly adds up, and can affect the dimensions or stability of the final product. And if this is overlooked during the process due to inadequate human supervision, you’ll expect additional time and material waste.

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