80% of the Weld Defects Arise From
20% of the Process Issues

by Andre Odermatt

It is well known that welding is one of the most widely used metal working manufacturing processes because of its low cost and highly productive method to permanently join metal pieces together. It also ranks among the manufacturing processes that have the highest variability and consequently a high potential for quality problems.

Every manufacturing process has visible cost and hidden cost. The visible cost are usually the direct labor cost and accountants can take the number of direct labor hours and apply a labor rate to obtain the direct labor cost “precisely”. Hidden manufacturing cost cannot easily be measured using a standard cost system but in discrete manufacturing it is a much larger portion of total manufacturing cost then direct labor. There are manufacturing processes with low hidden cost and high hidden cost.

Engineers should attempt to design products that require manufacturing processes with low hidden cost. Arc welding is a process with high hidden cost; however, it is impossible today to replace arc welding with a low hidden cost process. Hidden cost are those that are not quantified.  Accountants collect all these cost together and call it manufacturing burden!  In arc welding, such manufacturing burden typically includes filler metals, cables and hoses, consumable type spare parts, gases, protective clothing, exhaust systems, air filtering, production-scrap and rework.  Welders can and do influence these hidden cost.  As an example, MIG welding guns require contact tips, nozzles and insulators.  Does every welder use the same amount of contact tips?  Of course not!  Why would engineers design products that require a manufacturing process with so many variables and hence the potential for quality and cost problems?  The reason is that all these variables can be monitored and controlled if the person who performs the weld understands how to control these variables to make a sound weld.

It is difficult to envisage a key manufacturing process in the metal working industry that has so many variables that one single person must monitor and control simultaneously. But 80 % of the weld process defects arise from only 20 % of the process issues.

A properly trained welder knows this and is capable of monitoring and controlling these variables. Therefore, welders have a substantial influence on “hidden” manufacturing cost, maybe more so than many other direct-labor functions in other manufacturing processes. Smart managers know this reward their welders accordingly.