Selecting the right abrasive and using that abrasive correctly for metal fabrication applications and welding can make all the difference in maximizing productivity and minimizing cost. Still, with today’s tight deadlines, fabricators are tempted to use whatever abrasive is handy without considering which is the best one for the application. Some might even ignore some fundamental rules of grinding safety. The results can be lower performance of finished products, increased grinding and finishing costs, and lost productivity.
Selecting Abrasives That Make the Grade
It is important to realize that abrasive products come in various grades, which some manufacturers designate as good, better, and best (which is the scheme used in the tables in this article, in descending order: 1=best, 2=better, 3=good).
Metal fabricators who measure total grinding results and want to achieve the lowest overall cost for an application use the best abrasive products available for most of their work, reserving the use of the middle grade for high-productivity applications where only the abrasive cost is important. End users wanting the lowest initial cost are likely to select good abrasives but should be aware that such a choice may not be economical in the long run.
Fabrication and welding shop owners interested in determining total grinding results can work with their abrasive supplier to test and compare abrasives of various grades and alternative products from various manufacturers. Such tests, performed on-site, reveal relative abrasive cost based on price and wear rate and can even measure overall worker productivity based on a worker’s wages. Then, the relative abrasive cost can be added to the operator cost to determine the total grinding cost. What such tests typically show is that the most advanced (best) abrasive products usually last longer, work faster, make best use of the worker’s time, and often provide the most cost-effective choice.
Taking Down a Weld Bead
The first step in processing a weld is grinding to take it down as much as possible (see Table 1). The amount of work required for this step depends on the hardness of the material, the type of weld, the welder’s skill, and a few other factors. For the most part, taking a weld bead down is done most cost-effectively with a right-angle grinder. For this application, the abrasives used on these tools can be fiber discs, flap discs, or smaller versions of these products, used for greater control or to deal with smaller work envelopes.
Fiber discs remove excess material from flat and contoured surfaces with a fast initial removal rate. A few tips: