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Don’t Leave Weld Inspection to Chance

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Welding – One of the Most Common Joining Methods In Manufacturing

Welding is a fabrication process in which materials are joined together to produce an object or structure. The melting of a filler material commonly joins these materials and fuses them. This result is achieved using one of three main techniques: gas, arc, or laser welding.

 

Good welds are critical for the safety and integrity of a structure and affect the crashworthiness of a vehicle, so welds must be inspected upon completion. New welders are trained to inspect their welds after they have completed a job; however, it is challenging and time-consuming for welders to inspect all of their completed work for defects.

 

Weld defects can be defined as the irregularities in a given weld due to incorrect welding techniques or incorrect welding patterns. Many different defects can arise during the welding process. Some of the most common external welding defects are cracks, undercuts, burn-through, porosity, spatter, and overlap.

Various Welding Automotive Parts
physical-weld-defect-types

Common Weld Defects and Imperfections

Defects can be present at the surface of the weld material or the affected heat zones on the joined materials.

 

  1. Weld Undercut
    Undercuts occur in a weld when the base of the metal melts away from the weld zone, and a groove is formed. This defect reduces the strength of the joint.
  2. Weld Porosity
    Another common defect in welding can occur when small bubbles of gas or air get trapped in the welded zone; this is called porosity.
  3. Weld Burn Through
    A burn through produces a hole through the base metal. It often occurs when excessive heat is left on a particular portion of the metal for too long.
  4. Weld Spatter
    When welding, it is possible for some of the metal drops to be expelled from the weld and remain stuck to the surface of the welded material. This result is known as spatter.
  5. Weld Overlap
    Overlap is when the weld face extends beyond the weld toe. When an overlap occurs, the weld metal rolls out and forms an angle less than 90 degrees.

Costly Consequences of Downstream Weld Defects

These common weld defects can be catastrophic for manufactures; the news often reports weld defects that have caused automotive OEMs to issue massive recalls, sometimes costing hundreds of millions of dollars in damage to the brand’s reputation. In early 2019, for example, one of the largest automakers had to recall more than 10,000 pick-up trucks in North America due to incomplete and missing welds that could cause the rear driveshaft to crack and fall off. This error could lead to dangerous road debris for fellow motorists or result in a loss of power for the affected vehicle.

 

Even brand-new cars are not immune to weld defects. In another recall case that affected over 110,000 vehicles, the improperly welded bushing housings and joints could lead to lower control-arm separation. This error could lead to catastrophic consequences for the drivers and vehicles involved.

 

In another very high-profile recall that involves a multi-billion-dollar streetcar contract, one of the biggest cities in North America had to send more than half of their new streetcar orders back to the manufacturer after discovering more than 20% of the body structures suffered from weld defects.

 

The above three examples are just some of the weld defects that have been missed in the initial quality control process and were passed downstream, resulting in costly recalls and safety hazards. These oversights make 100% in-line weld inspections even more critical to ensure high-quality, defect-free deliveries.

Recall
Recall
Weldment inspection by welding gage
Traditional Weld Inspection Using Gauges
Weldment inspection by welding gage
100% Inline Weld Inspection Using 3D Laser Scanner

Traditional Weld Inspection Is Inadequate in the Mass-Production Environment

A quality assurance weld inspector does traditional weld inspections. The weld inspector will perform an inspection on the weld joint to ensure it is up to standard. However, this inspection is very difficult to do on mass-produced goods, as well as costly for the manufacturer because it has to hire an additional individual or a team of individuals to complete the job.

 

Quality assurance weld inspectors use different methods for inspecting the weld, including visually inspecting the weld, and a variety of tools, including magnifying glasses, flashlights, handheld gauges, tape measures, and calipers. The tools to be used by the weld inspector depends on the weld in question and the type of defect. These tests are only as reliable as the workers performing them. If the worker fails to complete a test or completed a test improperly, the reliability of the weld can be called into question, causing a big headache for the company. Weld inspection is often a tedious process that calls for a keen eye for detail and patience; inspectors can be responsible for inspecting hundreds to thousands of welds per shift.

 

Individual inspection is subjective to each inspector, making it very hard for manufacturers to ensure that each defect is caught. With an automated inspection solution, defect detection is based on measurements and mathematical formulas, ensuring that all defects that fit a certain set of criteria are caught before they can be passed downstream in the production line.

 

New methods have been developed that make weld inspection much easier for manufacturers who produce large numbers of products. Bluewrist Inc. offers a 100% in-line weld inspection solution. This solution uses a 3D profiler or 3D snapshot sensor to capture detailed surface characteristics of the weld. The weld can be inspected fully or broken down into individual sections for analysis and comparison against fabrication blueprints to guarantee the weld conforms to the specifications.

Conclusion – Don’t Leave Weld Inspection to Chance and Subjectivity

As we have seen in today’s manufacturing landscape, it is more important than ever to have strong, quality welds. The public demands higher quality goods, and welds are often of critical importance in the structure of a product. The reliability of a weld can play a huge factor in the success or failure of any company that procures welded products and in the public’s perception of the quality of that brand as a whole.

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