Red Seal Welder Practice Exam 2026 - Free Red Seal Welder Practice Questions and Study Guide

The primary difference between AC and DC welding lies in the direction of current flow. In AC welding, the current alternates direction, meaning it flows back and forth. This characteristic of alternating current can be beneficial in certain applications, such as when welding aluminum or other materials that require good cleaning action.

On the other hand, DC welding provides a constant flow of current in one direction. This results in a more stable arc and can be advantageous for processes that need a more focused heat input, leading to deep penetration and a cleaner weld. The consistency of DC is particularly favorable for many welding processes, such as MIG and TIG welding, especially when working with thicker materials or in situations where precise control is necessary.

Other aspects, like the voltage used or the temperature of the welding arc, can vary based on the specific welding machine settings and the material being welded, rather than being inherent characteristics of AC versus DC. The type of filler material is also not determined by the type of current but rather by the specific welding process and the materials involved. Understanding these fundamentals helps in choosing the appropriate welding method based on the characteristics needed for the job.