What you should know about robotic welding
August 23, 2013 by Lloyd Steed
In the fabrication and manufacturing world, quality and productivity are everything.
To remain competitive, companies need to look continually for ways to increase throughput and minimize defects, while also keeping costs low for parts and labour. In many cases, turning to robotic welding is a means to achieve those goals—for both the smaller job shop and larger manufacturing facilities.
The decision to implement a robotic weld cell, however, takes a good deal of consideration and planning if the system is to function in the most efficient, productive and profitable manner. And it requires a significant investment.
Fortunately, the long-term benefits of a robotic welding operation can be very positive. For companies who have already invested in robotic welding, but are looking to improve or better understand their operations, or for those considering the investment, it is critical to consider some key factors about the technology. Here, we will explore “what you must know about robotic welding” to make the most of the process.
1. There’s more to the payback on a robotic welding system than just speed
Justifying the cost of a robotic weld cell comes down to the ability to gain (and prove) a payback on the investment. Typically, that payback comes in the form of greater productivity and higher-quality welds (which minimize instances of costly and time-consuming rework), but there are other contributing factors to the return on the investment (ROI) in this technology. Robotic welding also offers the advantage of lower energy and labour costs, and in many cases lower material costs due to fewer instances of overwelding. Overwelding is a common and costly occurrence in semi-automatic welding. A weld bead that is 1/8-inch larger than necessary can double filler metal costs, but a robot can reduce those costs by only putting down as much material as necessary. Plus, robotic welding systems use bulk filler metals (600-pound drums, for example) that companies can often purchase at a greater discount.
For companies just considering the investment in robotic welding, it is important to consider how to calculate the payback. Assess the current part cycle times and compare those to the potential cycle times of a robot. A trusted robotic welding integrator or OEM can often help with this calculation. During this process, also consider the possibility of reallocating existing labour to other parts of the welding operation, where these individuals can add value to the process. Remember, up to 75 per cent of the cost in a semi-automatic welding operation is labour. If there is an opportunity to use that labour elsewhere to increase part production, the payback on the investment in robotic welding will increase.
Most companies—particularly smaller ones or those with frequent production changes—seek a payback on the robotic welding investment of no greater than 12 to 15 months. That time frame is entirely possible to achieve with proper up-front planning of the part blueprints, fixturing and general setup of the system. In some cases, companies may be able to justify a longer payback period if they know that their production needs will remain relatively static for longer periods of time.
2. Parts and product flow need to be consistent
The output from a robotic welding cell is only as good as the parts fed into it. In order to gain the advantages of these systems, it is critical to have accurate, repeatable part designs. Gaps, poor fit-up or poor joint access all prevent a robot from completing its job correctly.
The best part designs for a robotic welding application are simple ones that allow the robot to execute the same weld repeatedly. High-volume applications with low-variety parts are especially poised to gain the advantages of robotic welding. Companies should try to avoid part designs that require intricate tooling or clamping to hold it in place, as both can hinder the efficiency of the robot and also add to the up-front cost of the operation. That said, in some cases, companies may still be able to gain a good payback on the investment in tooling for slightly more complex parts, but they will need to weigh out the pros and cons of that cost ahead of time.
Companies also need to be certain to assess their overall welding operation for consistent process flow. Bottlenecks upstream can easily slow down the movement of parts into the robotic work cell and the ability of the system to function to its full capacity. A robot that sits idle costs time and money. Some companies may need to reconfigure operations or set up a flexible cell that can manage quick tool and fixture changes in order to minimize bottlenecks in the process flow. It is also important to have adequate labour to supply the robot with parts.
Again, companies should consider tapping the knowledge of a robotic welding integrator for advice and assistance to optimize process flow.
3. The MIG guns and consumables on the robot can impact productivity and profitability
The robotic MIG gun and consumables on a robot together are responsible for directing the current to the arc to complete the weld, making them integral components in the whole system. To gain the best quality and to avoid expensive downtime for maintenance, repairs or replacement, companies need to select a robotic MIG gun that is suitable for the amperage, duty cycle and cooling capacity needed in the application. Using a robotic MIG gun that offers inadequate cooling or amperage can cause performance issues and lead to premature failure—both factors that increase costs and downtime. Likewise, using a robotic MIG gun that offers higher amperages than necessary raises the total cost of ownership, as typically the cost of a robotic MIG gun increases directly in proportion to its amperage.
Companies also need to select their consumables—contact tips, nozzles, retaining heads (diffusers) and liners—carefully and manage them properly in order to gain optimal productivity and lower costs.
Heavy- or extended-duty contact tips and nozzles, for example, are a good choice to withstand the heat of higher amperage applications and can help
minimize downtime for changeover. Conversely, lower amperage applications or ones with shorter arc times may be better suited to standard-duty consumables, which also tend to cost less.
As with robotic MIG guns, carefully matching the type of consumables to the application can keep companies from having to address premature failures and/or accrue costly downtime (not to mention, lapses in production). It can also keep them from overpaying for consumables that may be too much for the application.
Companies should also consider the mode of welding when selecting consumables, as technology such as pulsed welding tends to be especially harsh on consumables and often requires heavy-duty options to withstand the heat of the arc for longer periods of time.
4. Peripherals can help improve the return on investment in a robotic welding operation
Peripherals refer to any additional equipment integrated into the robotic welding system to maximize its performance. They include items such as a nozzle cleaning station (sometimes called a reamer or spatter cleaner), anti-spatter sprayers, wire cutters and neck alignment tools. Unfortunately, some companies downplay the value of peripherals, viewing them as an unnecessary cost, and don’t realize that they can play an important role in reducing downtime and rework, improving quality and increasing productivity.
Consider a nozzle cleaning station, for example. As its name implies, this peripheral cleans the nozzle of dirt, debris and spatter, typically during routine pauses in the robotic welding operation. This cleaning action helps prevent shielding gas coverage loss that could lead to weld defects, expensive rework and lost productivity. The equipment also helps the front-end consumables last longer — and longer consumable life means less downtime for changeover and less expense for replacements. The addition of an anti-spatter sprayer further improves consumable life and performance by adding an anti-spatter compound that serves as a protective barrier against spatter buildup and other contaminants.
In the long run, the up-front investment in peripherals such as these can lead to measurable savings and provide a better return on investment by aiding the robot in doing what it does best: complete consistent, high-quality welds for longer periods of time than a semi-automatic welding operation.
5. Having skilled operators with proper training to oversee the robotic weld cell is critical
Robotic welding operations require ongoing supervision and maintenance, and that job needs to be completed by a skilled operator who has undergone the proper training. When considering an investment in robotic welding, companies should take care to evaluate the available pool of talent. As a rule, skilled welding operators and/or employees with prior robotic welding experience are the best candidates to supervise the weld cell. After the proper training, which a robotic integrator or OEM can typically provide, these employees can provide the necessary operating and troubleshooting skills to ensure the maximum uptime in the robotic welding cell.
As part of the routine training, it is absolutely necessary for the operators who will be overseeing the robot to be able to schedule and perform routine preventive maintenance on the system. Implementing preventive maintenance helps minimize unnecessary downtime and keep the robotic welding system running more smoothly. If problems can be solved before they arise and the robotic welding equipment made to last longer, it can protect the company’s investment, and ensure the productivity and profitability sought by this equipment in the first place.
Companies should consider vetting robotic welding integrators to determine the availability and costs associated with the training of personnel. Typically training lasts one to three weeks, depending on the certification level desired, and continuing tutorials are often available.
In the end, careful planning, good equipment selection and proper training are all “must-knows” for managing a profitable and productive robotic welding operation. So whether a company is new to robotic welding or trying to improve an existing operation, knowing some key factors can go a long way in helping to gain a competitive edge and to make the most out of the investment.
Lloyd Steed is a product manager with Tregaskiss. Learn more at www.tregaskiss.com.