This is the second in our series on TIG or Gas Tungsten Arc Welding of aluminum. We have chosen to focus on weld quality beneath the surface. On the internet, you will find no shortage of photos of gorgeous manual TIG welds. I can appreciate a “stack of dimes” weld bead as much as anyone. Symmetrical, perfectly spaced ripples do indeed showcase the skills of the welder. But sometimes beauty is only skin deep.
This week Jim Walkerr CWI (Certified Welding Inspector) will demonstrate how to use liquid penetrant (LP) for weld inspection. Jim has worked at ARC Specialties for 13 years as a welding technician. When he is not developing weld procedures or programming robots, he serves as our resident CWI. LP is an extremely sensitive nondestructive inspection technique. LP will detect small defects that radiography (X-Ray) will miss. It is also easy to learn and inexpensive to use, which is why we are showcasing it today. For under $100, you can inspect not just welds but also many other parts for cracks, laps, porosity, and other defects present on your parts’ surface. In the video below, the pretty weld is defective and the ugly weld is acceptable! The only difference was pre weld cleaning. The good weld joint was sanded and brushed with a stainless brush before welding. The bad weld was not. Aluminum is very sensitive to weld joint cleanliness. LP is a tool everyone needs in their toolbox. And not just for welding. I have discovered cracked wheel spindles on Formula V and Mustang race cars BEFORE they failed and hurt someone. Next week we use visual inspection to check fillet size and shape, plus look for root fusion on cross-sections.