Manufacturing managers and supervisors often look blindly at welding operations without really understanding how to measure and assess productivity. A common phrase heard in the shop could be something along the lines of: “I see arc radiation flashing on and off, therefore, parts are getting welded.”
The danger with that is that competitors both locally and globally are introducing lean manufacturing methods to all aspects of their operations, including welding. They’re streamlining their processes and they’re doing so by keeping a thumb on every aspect of production – and every weld that’s being made.
Therefore, to remain competitive, companies must continually seek out ways to improve their welding quality and productivity. Too many companies, however, aren’t looking at their welding processes at a granular level, which means that they can’t maximize profit potential or, worse yet, they lose orders due to inefficient welding methods.
This approach doesn’t just affect individual companies, though. To have a healthy economy, a good slice of the employment pie needs to be jobs where workers manufacture widgets. If we want to continue welding machinery, pressure vessels and other parts, we have to better analyze our operations under a manufacturing magnifying glass and then use world-class lean manufacturing methods.
If we ignore this challenge and do not introduce new and productive welding methods, more and more young people will be bumped into lower wage service sector jobs, or worse yet, the unemployment line. Incomes and tax revenue will be reduced and you, I and our neighbors will pay the price for not investing in welding productivity.
Factors for productivity
With that ominous introduction to welding productivity aside, let’s take a look at how to measure and improve it. One way to go about it is by looking at a deposition rate productivity measurement method, which is preferred for heavy welding applications, including multi-pass welds (think pound weld per hour). But, for sheet metal, single pass or autogenous applications, travel speed is a better measuring stick.
This is also the first category for making welding productivity improvements – while welding, weld faster. A primary variable to focus on is wire feed speed for the many variations of continuous wire processes. Wire diameter is another factor, and it may not be as simple as the larger wire translating into faster welding. Some studies suggest that faster wire feed speeds of a smaller diameter wire may translate into higher deposition rates.
The second category to consider in welding productivity is the operating factor, which is also referred to as arc-on time. In doing time studies and using arc timers, surprising data emerged surrounding welders using manual or semiautomatic modes of welding. The data indicated that some welders were only welding for 20 to 35 percent of the time. This then becomes the single most important value in trying to improve welding productivity. Therefore, efforts should be made to determine realistic operating factors for various applications. While non-welding tasks performed by welders are certainly needed, including cleaning and heating, productivity gains in this category would focus on ways to minimize the 65 to 80 percent of non-welding tasks performed by welders that do not add value to the product.
The third category influencing welding productivity is in regard to how much weld metal is deposited and what endeavors are being taken to increase productivity by decreasing this amount. For deposition rate-based applications, the total weld weight needs to be calculated for each welding method to be used, while total weld lengths only need to be determined when using travel speed-based welding productivity measurement.
Reductions in weld metal deposited can be made with alternate weld joint designs or in considering fillet welds based on throat dimension instead of the more usual leg length because the throat is a better measurement of effective weld strength. Interesting to note is that some structural steel welding codes allow smaller fillet weld sizes when the submerged arc welding process is used. ISO welding symbols take that a step further by permitting engineers to specify fillet size by leg length or by throat dimension.
Another improvement in doing less welding is in minimizing the amount of overwelding and rework welding. Some are surprised to hear that a specified 1/4-in. weld made oversize by 1/16 will take 56 percent more time. Simple geometric calculations prove this out.
So with the simple formula visualized, it’s easy to see: Better welding productivity includes faster welding, more arc-on time and less welding (less metal deposited). To further illustrate what may be possible, let’s review some situations straight from the weld shop floor.
Shop floor insight
In one case, a shop did not use formal welding procedures – an inspector explained that it was up to the welders to set their machines to make good welds. A series of similar-looking “good” welds were then made the same size. When asked if any were defective, the inspector replied that they all looked fine. From a productivity standpoint, however, there was a huge difference in the welds made with the minimum wire feed speed of 300 ipm to a maximum of 600 ipm. The result was a 100 percent increase in productivity.
To give an example of an operating factor improvement, let’s look at a supervisor who wanted the company’s welders to get more life out of their gun contact tips. His instructions were, “If you use a tip cleaner, you can get rid of the spatter and burnback.” But what he wasn’t factoring in was the cost of cleaning contact tips. Using six minutes of non-welding time for this work and using typical shop labor and overhead rates, welders would have spent $30 trying to get more life out of a $0.80 worn-out consumable.
In another shop, fillet weld sizes were measured in production and inventory and then compared to engineering drawing size requirements. What might have seemed insignificant – with some welds having leg lengths 1/16 in. oversize – resulted in a surprising amount of overwelding once geometric calculations were made. Overall, the 15 percent oversize welds would have translated into $600,000 of wasted welding each year based on the annual welding cost of $4 million at this specific shop.
To see the ROI of the cost to measure, implement and monitor productive welding methods, let’s take a look at a hypothetical, medium-sized shop employing 50 welders. With a combined labor, benefits and overhead rate of $60 per hour with each welder working 40 hours per week, the annual welding cost calculation can quickly be determined.
Now, let’s assume that a 10 percent savings could be achieved in each of the three categories previously explained. That 30 percent reduction would result in a savings of more than $1.8 million, which is a strong argument for investing in welding productivity. This is done by hiring the staff, doing analyses to optimize welding operations, and then purchasing equipment and materials if necessary to put new welding process control methods to work.
Hiring competent welders can be a challenge, which is sometimes compounded with comments like, “I need to weld the way I feel is right.” But to control welding quality and productivity, explicit procedures should be developed, documented and then actually used by welders instead of just having them come out of filing cabinets during quality audits. Shop floor monitoring of procedure compliance and supporting personnel who need training can help minimize an out-of-control welding free-for-all. Instead of having 50 welders doing their own thing, the goal is to have everyone use the best welding method for the job at hand.
Some companies have no problems handing out recruiting ads for welders when they have production hours available. On the other hand, some companies have been reluctant to hire welding experts to manage their welding and may pay the price with inefficient operations. Recognizing that small- to medium-sized shops may have difficulty justifying the expense of a welding technologist, there may be ways to develop that expertise with existing personnel or by using outside organizations.
Suppliers of welding products, like Praxair, often have skilled technical staff and, in some cases, also offer welding productivity audits and services. With confidence in the representatives and unbiased reports from these services, they can provide assistance in understanding the productivity of current methods and make recommendations for improvements.
Another option when developing expertise in managers and supervisors is with services like those offered by the Canadian Welding Bureau. The CWB, for example, has a welding productivity course and online tools that develop skills in measuring welding productivity. The site includes an online calculator that automates and simplifies much of the complex calculations required. Once accurate data exists for welding methods, informed decisions can be made on procedure selection and in taking an analytical approach to improving productivity.
No matter the company size, welding continues to be a labor-intensive process, but as this article has outlined, improvements in productivity are possible. By having realistic data for welding productivity and cost, intelligent manufacturing decisions can be made, thereby increasing profits to keep well-paying jobs in our backyard.
To further drive home the idea of improving welding productivity, there is a final valuable lesson to learn from a shop that did not weld to code requirements. The company didn’t use welding procedures to guide its 50 welders, and even if it did, only some of their GMAW/MCAW machines had digital controls making setup a challenge.
To assess the competence of the welders, they were asked to do a welding test and record the parameters they used, which required a manual technique on the analog control machines. Once all of the welders had completed the test, recommendations followed.
The final report, produced by OptiWeld, indicated a 53 percent variance in wire feed speed settings used by the welders, which is directly proportional to productivity and quality. Once that variance was reduced, productivity improved, proving that welding process control requires developing optimum procedures and then providing the training and resources so that they can be implemented across the board.