Automating Welding Operations
How can you justify the decision to automate the welding process?
By Kevin Summers
Business Development Manager
Miller Electric Mfg. Co.
By Randy Stevens
Director of Business Development
Windsor, ON, Canada
Automated welding systems have the potential to increase productivity, improve weld quality, reduce labor and materials costs, mitigate the welder shortage, and increase a company's overall profitability. These systems can be expensive, but they have come down in price substantially over the past 10 years, and the costs associated with automated welding equipment must be understood within the context of the benefits that automation can provide.
Automation won't be right for every company, however, and choosing the right system for your organization's operations is crucial to ensuring a wise investment. As with most purchasing decisions, successful investment in automation depends almost entirely on planning and preparation. The rewards can be significant, but when you make the wrong decision, so can the costs.
Below are seven factors that you need to consider when deciding whether and how to automate your welding operations.
- Why automate? A single automated welding system can do the welding done by as many as three employees—often with better-quality results—and eliminate bottlenecks that occur at the welding stage of the manufacturing process. In addition, an automated system can lower consumables cost by using only as much filler metal as is necessary. It can reduce scrap and rework rates by improving the visual and mechanical quality of welds, and reducing or eliminating spatter. Furthermore, automating the welding process can reduce the amount of labor required for welding, allowing reallocation of labor resources to elsewhere in your plant.
Also, in business perception is important. If you are in an industry where your competition is still welding by hand, investing in an automated system can provide you with a real, though not quantifiable, competitive advantage in the minds of customers.
- Payback: While the benefits generated by automation can be significant, those benefits come at a price. Many companies, especially smaller fabricators and those with frequently changing production lines, need to see a payback period of no more than 12–15 months to justify the investment required to install automation. On the other hand, companies that know their production needs will not change for years can often justify a longer payback period. Take a cold, hard look at your company's business, and determine what sort of work it does, and what projects are likely to be coming along in the foreseeable future. Do you plan to go after different kinds of parts than you work on today? Will that new business justify automation? In brief, what are the company's plans and objectives?
Looking strictly at current production requirements, calculating payback first involves determining your current product cycle times, and comparing those values to the cycle times an automated system can achieve. If you need to produce X number of parts per week, for example, and an automated system can produce those parts in 1/4 the time required by manual welding, it's obvious that productivity can be increased by 75%. Bearing in mind that approximately 70% of a welding operation's costs are for labor, the table titled Welding Costs shows the labor-saving potential of an automated welding system.
Overwelding is a common and costly occurrence in semiautomatic welding. A weld bead 1/8" (3.1-mm) larger than necessary can double your filler-metal costs. An automated system can reduce filler-metal costs by only putting down as much material as is actually needed.
Automated systems also use bulk filler-metal drums, which can further reduce filler-metal costs by requiring fewer changeovers and yielding bulk-purchasing discounts. Using bulk tanks for your shielding gas, another highly recommended step in optimizing automation capabilities, will further increase any operation's return on investment.
- Making the leap: Automating a welding cell won't be the right course of action for everyone, but the capabilities of automated systems and their increasing affordability is making cell automation a good choice for many companies. If the system is to be automated, shop-floor personnel must be able to provide the robot with a consistent supply of material, and ensure that the parts being welded do not accumulate in another part of the plant. If the robot only moves the production bottleneck from the welding cell to the painting booth, for example, then productivity has not improved.
Repeatability and measurability is a precursor to automation. The company that does not have a blueprint (preferably an electronic blueprint) probably won't be able to automate the welding of that part. A thorough understanding of existing productivity is also required, to provide a baseline from which to measure the improvement delivered by the automated system. Further, for successful, economical automation, parts should have large batch runs (although there are some exceptions to this rule), tolerances within thousandths of an inch, and configurations that allow access by an automated gun.
Make sure your company employs the workforce needed to automate its operations. An automated welding system requires a trained operator to make sure it runs properly. Because it takes longer to become a skilled welder than it does to learn how to operate an automated welding system, it usually makes sense to train a welder to operate the automated system, rather than trying to train a tech-savvy employee in proper weld-quality identification and troubleshooting.
Automated systems generally require three-phase 480-V electrical power, and only reach their full potential with the use of a bulk gas/manifold system. Does your company have these resources in place? If not, consider the cost of installing such equipment when you set out to determine whether to make the leap into automation.
- Automation options: It's essential to realize that there are two basic types of automated welding systems—robotic and fixed. A robotic system is what most people think of when they speak about automated welding. This type of equipment includes a robotic arm that can move along several axes, and a positioner that moves the part to be welded. Robotic systems are more expensive and more complicated than fixed automation systems, but they can be reprogrammed to accommodate different product lines if the demands faced by your business change. This capability makes robots especially attractive if you own or work in a small, growing fabrication shop.
In a fixed automation system, either the gun or the part is fixed in place, making the system less able to accommodate changes in product configuration and design. A product that requires only straight or curved welds along a single plane is usually a good candidate for a fixed automation system.
- Think about automation components: Planning a successful automation effort involves carefully choosing the equipment that will make up the system, including the positioner, tooling, welding power source, robot, gun, welding wire, and peripherals. As its name implies, the positioner is responsible for turning, rotating, or otherwise moving the part into an optimal position to be welded. In many cases, this action involves moving the part so that the system can weld in a flat position for optimal deposition efficiency.
The tooling holds the material to be welded in place, and is one of the most critical components of an automated welding system. Because the gun moves along exactly the same path each cycle, if the weld joint is out of place by as little as a few thousandths of an inch, the resulting part could end up in the rework or scrap bins. Simply designing the tooling correctly at the beginning isn't enough, however. The tooling is subject to mechanical wear, heat distortion, and other factors that can cause weld defects, so a trained operator must ensure that the tooling continually maintains acceptable tolerances. Power sources, especially those designed specifically for automated welding, can monitor and respond to the arc conditions within milliseconds, making it possible to reduce heat input to the materials, increase travel speeds, reduce spatter, bridge gaps, and work with a wide variety of metals. Choose a power source that offers these benefits.
Selecting the right gun and welding wire
can also have a significant bearing on the productivity and profitability of your operation. The gun and wire should be chosen based on how they perform in conjunction with the rest of the system's components and parts. Because it's subjected to intense heat, spatter, and other elements, the gun must be very durable to avoid maintenance downtime. The gun should also be easy to service to minimize any downtime required for spatter removal, for contact-tip changeover, and for other routine maintenance.
Finally, robotic peripherals, such as nozzle reamers, anti-spatter applicators, and wire cutters should also be considered and included in the automation effort. These devices can improve uptime and welding performance.
- Planning for the future: Predicting a company's automated welding needs in the years to come will help determine the type of system it needs. If the operation is making a part that easily lends itself to a fixed automation system, for example, but is not confident that the part will be made three years from now, a robotic system might be the better choice. That type of automated welding system can be reprogrammed and retooled to accommodate the needs of the shop floor in the future.
- Throughout the journey: The company selected as an automation partner, whether the welding supplies distributor, a robotic systems integrator, an equipment manufacturer, or an independent consultant should be available with support and service throughout your organization's transition to an automated welding system, not just until you install the robot. Also, most reputable robot manufacturers provide at least a week-long training course, as well as 24-hr support hotlines and field service technicians who can make on-site repairs and/or function as consultants and advisors.
The popularity of automated welding operations is growing because of their welding capabilities and the return on investment that they can provide. Any company that has a repeatable part, efficient material flow, and a desire to increase productivity, should at least consider automation. In addition, take it as a sure thing that the competition is also doing so. The first step toward deciding if automation is the right approach for your company will be to contact a trusted expert who can conduct an onsite analysis of your specific circumstances, recommend the appropriate equipment and configurations, and calculate the payback you can expect.
This article was first published in the December 2008 edition of Manufacturing Engineering magazine.
Published Date : 12/1/2008