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The Differences in Gap and Contact Capacitive Discharge Welding

Both gap capacitor discharge welding and contact capacitor discharge welding are based on the same general principles and methods however, there are differences in the process that are important to understand.

At Image Industries, we often get questions about which is the best option to consider. To help our customers and those interested in both gap and contact capacitive discharge welding, here is a basic review.

Contact CD Welding Summary

The process of contact CD welding starts with the operator positioning the CD studs in the correct location pulling the trigger on the gun. This causes an electrical pathway between the gun and the metal piece. Pulling the trigger results in a short circuit, which causes a discharge of the capacitors that vaporizes the tip of stud. This vaporization creates an arc that melts a small amount of the base metal as well as a bit from the bottom of the stud.

While this melting occurs, at the same time a spring in the gun thrusts the stud down and into the molten material of the base metal. The molten material rapidly cools, welding the stud in place permanently. The entire process takes 0.012 seconds to complete.

Gap CD Welding Summary

With softer materials or materials that melt and cool incredibly fast, such as aluminum, the contact CD stud welding process is not effective. Gap CD welding can avoid these issues by accelerating the stud quickly into the molten pool. This also reduces the weld time by about half.

With this process, the stud weld gun accelerates the stud towards the substrate or work piece with precise timing and pressure. When the trigger is pulled the stud is moved towards the base metal and, as soon as it touches, the power source provides the energy needed to vaporize the tip and create the arc while at the same time fusing the capacitor discharge studs to the work piece.

If you have questions about the differences in contact and gap CD welding for any project, contact us online or give us a call at 800-722-7883, we would be happy to discuss your options.

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