To implement automation in welding effectively and maximize your ROI, you need to approach it as a system, not merely a torch-wielding robotic arm standing in for a human welder. Thinking about the flow of parts into the welding cell, how they’re fixtured and welded, and where they’re transferred next may present opportunities to boost efficiency, save space, or open up production bottlenecks.
If you’ve thought about adding automated welding to your facility, there are many things to consider from equipment and system design, to safety, to how it will affect your current welder employees. Read on to see if this popular robot application is right for you.
A Snapshot of Automated WeldingOne of the top industrial robot applications is automated welding. Assembly Magazine cites the International Federation of Robotics’ findings that 50 percent of all the world’s robots are used for welding: 33 percent for spot welding, 16 percent for arc welding, and 1 percent for some other type of welding operation.
And we can expect to see it expand in the near future. Between 2018 and 2023, the market for welding automation is projected to grow at a CAGR of 8.91 percent, especially in the automotive and transportation segments.
It’s been almost 60 years since General Motors first used their UNIMATE industrial robot for spot welding in 1962. What started as a way to protect workers from the most dangerous, undesirable jobs was gaining popularity across the automotive and other industries by the 1980s. Today’s manufacturers have embraced robotic welding and now many are finding ways to integrate it into larger automated systems to save time, compensate for worker shortages, and improve quality and production.
Most robotic welding falls into three categories: arc welding (generally MIG or TIG), spot welding, and laser welding. Sheet metal is by far the most common material, usually made of either aluminum or mild or stainless steel, but components like nuts, caps, and tubes can be welded by machines too. Applications are almost limitless thanks to the dexterity of multi-axis arms and thoughtful design of fixtures and sensors.
At first glance, it might appear a robotic arm and torch are all that’s needed to automate the welding process. There are actually several components required for optimal performance and, even more important, human safety.
It’s more accurate to view automated welding as a system that includes the entire work cycle: a part enters the cell or work area, it’s positioned with fixtures, the weld is completed, the part is ejected or removed, and then transported out of the work area.
Most of this full cycle can be automated, not just the actual welding, depending on the application and production goals. An experienced automation integrator can help you decide which equipment and configuration is best for your application.
In addition to these components of a robotic welding system, you can design a more fully integrated system between the welding cell and other production areas. Equipment like conveyors, pick and place arms, machine tending robots, and inspection equipment can streamline operations.
There’s more than one way to automate your welding applications. One of the first decisions to make is between Commercial Off the Shelf (COTS) or a custom system.
COTS equipment is sometimes called “pre-engineered” because components are sold as a package deal, usually a robot, torch, welding power source, and safety guards. These systems are generally designed as stand-alone, one-size-fits-most cells, and are designed in a way that upstream and downstream processes aren't as affected when installed. Some vendors offer a choice of power source or other equipment to customize the cell, and additional accessories or peripherals like sensors or nozzle cleaning tools/reamers may or may not be included as part of the package.
Even a basic system won’t be ready to run right “out of the box” without some amount of configuration and setup time. Especially if your facility is new to automation or robotics, troubleshooting and optimizing workflow may present a challenge, so it’s critical to verify what support and training is included with the package.
For example, you will probably need fixturing to hold the pieces to be welded in place. The COTS equipment vendor may be able to supply fixtures, but an automation integrator can also design custom fixtures. Integrators can also set up the cell, program the robots, and configure the welding parameters to achieve your desired weld quality and specifications.
While they may be cost-effective up front, because they sometimes come with a limited selection of components, pre-engineered cells may not be suited to complex welding tasks or fit seamlessly into a production line. It’s important to consider if a COTS cell will fit in with your existing processes up- and downstream or if it will disrupt the workflow or create inefficiencies.
Custom equipment is generally designed and installed by an automation integrator. Because no two manufacturers have the same process, custom systems let you tailor the system to what’s most important in your situation. The first step in working with an integrator is close analysis of your unique requirements and production goals, along with the general flow of your manufacturing facility.
Only then are specific pieces of equipment incorporated into a design. The time and expense are usually higher up front, but the end result is a welding system that does exactly what you need without extras you can’t use. Many custom systems can also be expanded or integrated with other workstations or processes as your needs change.
Your facility’s size, production volume, and mix of products affects the COTS vs. custom decision too. Smaller facilities with limited space and budget for large, dedicated systems might do better with a compact custom welding system designed to nestle between other work cells.
Larger operations or those with a low-mix and high-volume may find that a pre-engineered welding station meets all of their needs easily. Or, to make a high-mix, low-volume operation more efficient, an integrator may bring together single components to coordinate material handling, communications between devices, fixturing, and the actual welding machine.
Are you better off with a stand-alone welding machine or incorporating more than one type of machine to manage the flow of components in addition to welding? There is no single right solution for everyone: it depends on part volume, complexity of welds, and resources available (including money, available time to make the change, and worker availability and skill).
Automation doesn’t have to be all-or-nothing. For example, a manufacturer can have “islands of automation” for some areas such as cutting, welding, inspection, while assembly, machine tending, and material handling remain manual.
Integrated systems often use computer software and connected devices to coordinate components. One powerful tool is programmable automation controllers (PACs), which synchronize equipment with a human-machine interface (HMI) and teach pendant, gather data about speed and motion, and even make adjustments to operations based on data from other equipment it’s connected to.
Examples of integrated welding systems include:
Robots can also coordinate with human operators to perform parts of a larger task. For example, while a human operator loads the next part at the front of the welding cell, a robotic arm with a gripper can remove a finished assembly from the weld fixture through the back, then place it on a conveyor.
Automating one task/process can have implications up and downstream. For example, the great precision of robot welding means there’s less room for the variations in cut angles or seam alignment that a skilled human welder can easily adjust for. Cutting/forming must be held to tight tolerances so that part fit-up is at a level a robot welder can work with.
Another consideration is the increase in throughput that may result due to the high speeds possible with automated welding – you need to be sure operations up- and downstream can accommodate the change and that you have a plan for transferring more parts quickly.
The trained eye of an automation integrator can find ways to make changes while still accomplishing production goals, or even improvements to efficiency, safety, and worker availability.
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According to Assembly Magazine, inappropriate fixtures contribute to 40 percent of rejected parts, so it’s important to realize that without the right fixturing to hold parts in the right place, the robot can’t make accurate welds.
In other words, because robots precisely repeat the same weld paths every cycle, in order to have repeatable, accurate welding automation, the components to be welded must be held in the same correct position each cycle too. And because robots repeat identical motions at a relatively quick pace, defective parts can pile up quickly.
At a minimum, fixtures need to accept, position, and hold components and discharge weldments quickly and repeatedly. Fixtures must also be durable and not interfere with electric, gas, or fiber optic lines (i.e., the robot’s “dress package”).
In addition, many manufacturers want to stay flexible with their automation equipment – why spend money on a welding robot that can only be configured for a single part? Part families, sets of similar parts with minor variations, are common in automotive and other types of manufacturing, and are one area in which flexible fixturing allows for greater automation. Built-in fixture changeover to accommodate all the variants of a part, or even entirely different parts, often impacts throughput and ROI.
One of the benefits of automating processes like welding is the opportunity to examine them for ways to change or improve workflow or physical set up. When fixture changeover comes into play, it helps to think of it as one aspect of a larger system. For optimal efficiency in welding automation, designers also need a plan for storage and retrieval of fixtures when not in use. Incorporating multiple arms, conveyors, or even mobile autonomous carts to help with changeover tasks can make the process more efficient.
There’s a range of fixturing options from simple to complex, and as with most things, the best option is the one that accomplishes your current production, fits into your budget, and addresses plans for any future expansion. At one end of the spectrum are fixtures installed and removed manually with a wrench or hand crank.
Other options include fully automated, servo or pneumatic-driven changeover, where the machine automatically swaps out tools based on a barcode or a few taps on a touchscreen HMI. Sensors and vision cameras can also verify alignment of plates and parts, and sensors can locate weld seams or verify positioning.
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For example, a car seat adjustment mechanism may come in three of four variants depending on the model it goes into. Automated fixturing and changeover can be designed to scan the barcode on the parts, shift the correct fixturing into position, verify that the right parts are being welded, and then complete the weld.
In some applications, vision-guided fixtureless welding is a cost-effective solution. Advances in multiple arm control allow a group of arms to be programmed to coordinate on a process or task, which reduces dedicated tooling and fixturing.
For example, material handling robots equipped with vision cameras can grip and lift several types of frames, brackets, or parts as they move by on conveyors and position them for a welding robot, serving as the weld fixtures themselves. This flexibility saves time and space usually required for dedicated fixtures and tooling.
Quality problems and weld defects, such as hot/cold crater cracking, fissures, porosity, undercutting, incomplete fusion or penetration, and spatter happen with automated welding and need to be identified and fixed. Here are some tips for optimal quality:
Consider if problems are due to recent changes to the process, consumables, or robot programming.Experts debate how extensively automation replaces human workers, but most agree automation changes the very nature of welding and industrial work.
Robotic welding systems shift the manual work of aligning parts in fixtures, welding seams, and moving the weldment from one station to another from a person to a machine. Now the worker’s primary role is maintaining the flow of parts and keeping the machine running, loading and unloading pallets or trays, and overseeing the entire welding system. The work has a broader scope, encompassing multiple dynamic factors.
Despite this shift, operators still need to understand welding, spot and troubleshoot defects, and apply welding skills even if they’re overseeing a robot and not holding the gun in hand.
Welding automation also benefits employers by:
Most of the dangers of manual welding persist in automated systems. In addition, robots, conveyors, and automated material handling equipment present additional risks to safety. As more and more companies turn to pre-engineered and custom robotic welding systems, worker safety is always a top priority. There are many ways to ensure and enhance safety, such as:
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