How to choose nonwoven abrasives

Abrasive products used for finishing metal and nonmetallic workpieces are generally categorized into two main groups: bonded abrasives (used in grinding wheels) and coated abrasives (like belts, discs and sheets). These products are employed to remove stock during the production process. But there is a third category of abrasives that serve a specialized and highly essential function of preparing and applying the final surface finish, which can be critical to the performance and appearance of the workpiece. These are nonwoven abrasives. These products are manufactured using a web of nylon fibers that are bonded together with synthetic resins. The fibers are impregnated with abrasive grain, producing a durable, cushioned, 3D material that is pliable and conformable to the workpiece. Nonwoven abrasives can be ideal for deburring, cleaning and imparting the desired finish to many materials. A basic understanding of how these products are created and how they should be used to their maximum benefit can help the metalworking manufacturer achieve the needed surface finish. Role of nonwoven abrasives The job of nonwoven abrasives begins where other grinding products leave off. The relatively non-aggressive nature of nylon and the abrasive grit used in nonwovens make them excellent finishing tools. With their open mesh construction, nonwovens are waterproof, washable and resilient. They resist loading and rusting and are nonconductive. In a standard nonwoven design, abrasive grain is uniformly dispersed throughout the nylon web, providing a continuous supply of new grain as the old grain and fibers wear away when being used. While 60 to 80 grit abrasives are considered intermediate sizes in other products, they are believed coarse for nonwoven products. Nonwovens can be used in a range of metals, including aluminum, brass, copper, nickel, chrome plate, stainless steel and titanium, as well as other hard-to-grind materials such as ceramic, glass and plastic. Used as wet or dry, nonwovens enable the user to have a consistent, uniform finish and conformability to irregular surfaces with minimal smearing and discoloration of the workpiece. Necessary components While nonwovens are made uniquely from common coated abrasives, both products use many of the same abrasive minerals. Silicon carbide is sharper, cuts faster and produces finer scratch patterns on most surfaces. Aluminum oxide is more durable and lasts longer. It is also more aggressive on hardened steel parts and produces less discoloration on aluminum. Grit refers to the size of the abrasive grain impregnated into the nylon web (the lower the number, the larger the grain). Use of large particles (coarse grit) results in a more aggressive cut and a coarser finish. Smaller size particles in a nonwoven product produce a fine surface finish, if all other conditions are equal. Specifying a conventional bonded or coated abrasive product, the purchaser selects a specific grit size, e.g. 120 grits. With nonwoven abrasives, one of the following designations is used: Density is another term used in specification that may be unfamiliar to someone who buys conventional abrasives. This refers to the amount of bonding agents and abrasive grain that has been compressed into a nonwoven product. In general, harder density products cut faster, last longer and produce finer finishes than softer density products. However, softer densities offer more conformability to the work surface and less tendency to load or burn the workpiece. Sizing and bonding agents are two factors in the design and manufacture of nonwoven abrasives. Fiber size has a significant effect on the product's cutting characteristics, while the type of waterproof resin used to bond the fibers together and anchor the abrasive to the web can alter the product characteristics. The nonwoven manufacturer selects the appropriate fiber sizeRacing Archives