Blend Welds like a master

After completing various sections of welding metal together, the next step is achieving a seamless finish.

Blending welds is the action of combining two metal pieces together through welding and the grinding down of the weld to  produce no visible seam.  

Before welding can commence, the workpiece needs to be cleaned to remove any rust or mill scale that has formed. For this application, non-woven abrasives, like a rough cleaning disc, or non-woven flap disc is ideal. Once the cleaning process is completed you can determine the type of weld that is required. 

Two types of welds can be distinguished. MIG welding, also known as Gas Metal Arc Welding and TIG welding, known as Tungsten Inert Gas Welding. Where MIG welding is known to be a low cost yet highly productive method of welding, and mostly used on common metals like carbon steel and alloys, TIG welding is a more precise form of welding and requires a bit more skill, as it results in a neater and smaller weld. 

Grinding a weld on stainless steel gate.

THE PERFECT FINISH  

The choice of weld will depend on the required inish, which is determined by the original material of the workpiece. Carbon steel is almost always painted after welding, whereas stainless steel usually requires a polished finish. If working on carbon steel, not all welds need to be removed, as the seam will not always be visible. Stainless steel, like elevator panels, or handrails on the other hand requires a highly refined finish to disguise scratches.   When preparing to blend a weld, it is important to ensure that you are working with a clean, good weld, free from air bubbles or porosity. There should also be no undercut,  for example edges that do not intrude or fold into the surface of the material.  

CHOOSING THE RIGHT PRODUCT 

The market offers different product options when it comes to blending weld applications. Removing welds can quickly be accomplished with any grinding disc by using a criss-cross motion to knock down the high spots when grinding, as this will remove stock quicker and easier without damage to the workpiece around the weld. 

It’s important not to use too much pressure when using a grinding disc, as you don’t want to grind into the weld causing damage that could potentially weaken the weld leading to it needing to be redone. In some cases, a used grinding disc might offer the perfect solution, as it will be less aggressive on application. It’s important to note that the final required blend will require further rework with a finer grit abrasive product after grinding. 

If opting to use only one product, a flap disc is ideal to remove both the weld and produce the final blend.  

Fibre discs can be used as a third option to blend welds. A P80 grit used at a low grinding angle of about 45 degrees will blend the weld perfectly. Once satisfied with the finish, a finer grit fibre disc, either P120 or P150, can be used to remove the scratch marks. Take care not to use excessive pressure during this application.   The surface is now perfectly prepared for painting. Should a mirror finish be required, non-woven abrasives can be used.

For more information, Call: +27 11 271-6400 | Email: [email protected] | Visit: www.grindtech.com

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