An abrasive overview
Abrasives are a necessary part of welding. Grinding, cutting and even polishing are all done with abrasives. Becoming familiar with the different types, brands and applications is important to producing a better quality product. Knowing how to select the proper abrasive is a key issue for many guys in the field. The rapidly changing technology in abrasives means that some study and investigation into the latest product offerings is necessary. Flap disks are hugely popular right now. The flap disk is capable of grinding, smoothing and polishing the weld. It’s not made for removing large amounts of material at one time, but with gentle pressure, a significant amount of material can be removed surprisingly fast and the finish will be smoother with less traces of grind marks. Of course large grit flap disks can almost equal the grinding power of a hard disk, but they do wear away the abrasive portion quickly and are quite costly.
Hard disk abrasives are, of course, made for general grinding applications, but there are all levels of quality, durability, and speed. The extended grind disks allow the disk to wear more slowly. These also may be more aggressive in material removal due to the bonding agents, the type of abrasive bonded into the disk and the overall design. These disks are often just as cheap as a regular disk, but not always.
You have to shop and compare as well as test these disks side by side on similar material in the same application. A good indication of a cheap disk or a fast wearing disk, is you can generally see a brown, black or gray cloud spewing out along with the sparks. A long wear or fast grind disks won’t put out that much dust, though the sparks may often be seen as larger or longer in nature. Special abrasives for Grinding aluminum are out there for grinding aluminum and stainless both of which have similar requirements while grinding.
Stainless is less tempermental than aluminum, but it heats up quickly and can warp on thin sections of material, so a light touch is needed with an ordinary disk. But a special wheel is made that will grind both. This wheel has a waxy like substance impregnated into the wheel which prevents the “load up” of melted aluminum from accumulating in the pores of the wheel, possibly resulting in a detonation. This disk also works well for Stainless and keeps things more cool by the lubricating properties of the waxy material.
Before this wheel was available, it was common to dress a wheel with bee’s wax to prevent the abrasive from accumulating the melted aluminum in the pores, and offering lubrication while grinding. Though it’s still commonly done, newer methods are more efficient and more time conscious. This is but one example of many that indicate the need to stay up with the latest abrasive technology. A lot of companies offer catalogs with full description and applications of their abrasives. If you are needing specific help, it would be a good idea to drop by your local welding supply store and pick up a couple of catalogs to help you make you most informed and safest choice.