Tips & Tricks for Identifying a Weak Weld

Tips & Tricks for Identifying a Weak Weld

Much of our modern society depends on welding to hold it together. When you consider all the structures that support us in our day-to-day lives, the importance of high-quality welds becomes readily apparent. There are the cars, planes and ships that transport us; the bridges we cross; and the buildings we visit every day. All are, in part, held together by welds that must be strong and durable.

Welding is the process of using heat, and sometimes pressure, to join two metals together. At its most basic, it’s a relatively simple undertaking, but it takes real craftsmanship and scientific knowledge to form top-of-the-line welds that pass the test of time.

Part of what makes a good welder is knowing the appropriate technique to use in any given situation. Armed with that knowledge, and some specialized equipment, a welder is prepared to tackle nearly any job.

TIG vs MIG Welding

Two primary welding techniques are used in metal fabrication: metal inert gas (MIG) and tungsten inert gas (TIG). Similarities exist between the two methods, but each serves its own purposes with unique advantages and limitations.

  • TIG welding is the more hands-on approach, giving the welder more control over accuracy and temperature. That control is crucial for projects with tight tolerances or precision requirements. There are also fewer material restrictions with TIG welding. Used frequently on steel, it is also known for producing excellent results with chromoly, aluminum, nickel alloys, magnesium, copper, brass, bronze, and even gold.
  • MIG welding can be completed faster than TIG welds, and craftsmen often use it when faced with thicker materials that require a heavy-duty bead. MIG’s use of filler material allows pieces to be fused together without heating them all the way through.

The welding team at Badger Sheet Metal Works (BSMW) weighs all factors of a project to determine which technique will enhance the resilience of the weld and prevent defects.

Characteristics of a Bad Weld

It’s critical to identify a poor-quality weld or defect before it becomes a safety risk, but it’s not always easy to know what to look for. While testing is required to fully inspect the integrity of the weld, there are subtle characteristics that are indicative of a bad weld.

In general, a secure weld looks consistent and won’t be visible at all if truly seamless. However, because of the variety of welds that are possible, there aren’t specific rules for identifying good and bad welds in all circumstances. Instead, each method of welding has individual indicators.

TIG Welding

TIG welding is one of the most complex processes, and if a welder hasn’t mastered the technique, it will be apparent in the end result. Signs of a poor-quality TIG weld include:

  • Slag
  • Burn through on the underside of the joint, cauliflowers
  • Wide, flat beads that lack a distinct pattern
  • Undercut edges
  • Tungsten particles in the weld
  • A weld size that is unequal to the joint
  • Inconsistent bead placement
  • Hard-to-remove heat marks
  • Lumps at the start and stop sections of the weld

Many factors within the process can alter the appearance and strength of a TIG weld. Some of the most common issues occur when the wrong filler metal is used, the workspace or equipment isn’t clean, or the weld gun’s amperage is too high.

MIG Welding

A bad MIG weld is easier to identify compared to a TIG weld because there is no pattern. It should be as smooth and uniform in appearance as possible. Characteristics of a bad MIG weld include:

  • Slag
  • Holes
  • Undercut edges
  • Cracks down the center of the bead
  • Breaks in the weld
  • Dips or craters in the bead
  • Splatter around the joinery
  • Irregular peaks on the profile

Additionally, if a MIG welding line is too thin, it won’t have the strength to hold materials together.

A high-quality MIG weld is achieved when the craftsman is mindful of their voltage, shielding gas, and wire feed speed/amperage.

Welding Tests

Beyond checking welds visually, BSMW has formal testing procedures in place to ensure the work was created at the correct size, lacks defects, and is aesthetically acceptable. A weld’s internal characteristics are also inspected to identify porosity.

BSMW uses the following weld inspection tools and procedures: Liquid Penetrant Testing, Radiography Testing, and Magnetic Particle Testing. Every weld is also inspected per AWS standards.

BSMW’s Welding Capabilities

BSMW offers MIG, TIG and seam welding services. Its welders hold AWS D1.1 (carbon steel), D1.2 (aluminum) and D1.6 (stainless steel) qualifications and have extensive experience adhering to custom weld qualifications requested by customers.

Two onsite Certified Welding Inspectors (CWIs) provide quality assurance during the entire production process. There is no need to contract with third-party CWIs that increase the cost and timeline of your project.

Contact Badger Sheet Metal Works for more information about the fabricator’s welding qualifications and how they apply to your project.

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