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Manufacturing Technology Insights | Sunday, November 12, 2023
Fremont, CA: Regardless of the application, properly preparing metal for welding is crucial to achieving high-quality results, maintaining consistent productivity levels, and minimizing costs, particularly those related to rework and downtime. In order to ensure a sound and strong weld, the surface should be as clean as possible before welding. Thus, it is essential to provide operators with the necessary knowledge and skills to complete weld prep correctly and efficiently in order to streamline the overall welding process.
Plan your approach
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When planning your weld prep strategy, consider the following questions:
● What are the requirements for the welding process? Shielded metal arc welding (SMAW) allows some impurities to remain on the surface of the material, but requires more postweld and interpass cleaning. Welding with gas metal arcs (GMAW) and gas tungsten arcs (GTAW) typically requires more preparation and a cleaner surface, and requires a lesser amount of cleanup after the welding process.
● What is the best media to use when working with the material? It is necessary to remove all mill scale from some materials, such as hot-rolled steel, before welding. Abrasives of high performance, such as ceramic, should be used to prepare welds for harder materials, such as INCONEL alloys. Nonferrous and soft materials such as aluminum may be more susceptible to wheel loading, also known as clogging.
● What is the required final finish? Knowing and understanding the finish requirements is crucial when selecting an abrasive.
A perfect fit
Torch/plasma cutters, shears, laser/waterjet/CNC tables, and manual tools such as cutting wheels can all be used for cutting. They are all different. For high-quality results, consistent productivity levels, and cost reductions, metal must be properly prepared for welding. In order to produce quality results, it is imperative that the initial cut be as clean, straight, and consistent as possible.
Cleaning and Prepping
Preparation for the initial welding pass begins after the material has been cut and beveled. It is important to remove all mill scale, chemicals, contaminants, and coatings from the base material in order to guarantee proper weld penetration and eliminate impurities, porosity, and inclusions. On both sides of the joint, ensure that the work surface is thoroughly cleaned within an inch of the joint
Selecting the Best Grit
Extra material can be removed or the surface can be harmed when using an abrasive that is excessively coarse. A finished product that has too much material removed may not meet final tolerances and standards. It may also be more challenging to notice surface flaws and cracks during visual inspection due to the rougher scratch pattern. With a finer abrasive, material may not be removed as rapidly, but it is frequently more productive, can reduce the number of passes required to reach the desired finish in less time, and can help avoid rework.
Selecting the Right Abrasive
Different abrasive profiles can be used for different jobs. Abrasives are designed to remove base metal and cut metal. It is important to remember that heavy coatings and base material can build up between the grains of abrasives due to their construction and decrease their ability to cut.
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