FandMmag.com |

Talking with readers about their critical issues, finding and training shop-floor workers tops the list nearly every time. That said, the fundamentals will always hold tremendous value. With this in mind, F&M offers periodic features on the bedrock principles of metal manufacturing. This month, we cover industrial brushes. Material for this feature comes from Brush Research Manufacturing Co., 323-261-2193; Fax: 323-268-6587; 4642 East Floral Drive, Los Angeles, CA 90022; www.brushresearch.com; and is used with permission.

Each filament of an industrial brush is, in itself, a cutting tool. Using these thousands of filaments at the proper speed and pressure to the workpiece gives, in the end, the desired result—a clean, polished finish, deburred surface, blended edge, and so on, depending on the application.

Many hold a widely believed, though false, impression that these brushes perform a "scrubbing action" coupled with a great deal of pressure or friction. The reality is quite different.

Suppose an operator has a very sharp edge on the part to be finished; a wheel brush may work extremely well by removing the edge and creating the desired radius without damaging or removing the metal on either side of the edge. This can only happen by having the right diameter of wheel brush, the proper wire size depending on the workpiece material, the face width wide enough for sufficient product coverage, sufficient power and speed with the brush rotating near its maximum safe limits, and the brush wire tips applied only to the edge that requires the metal removal. The brush wires should not be deflected or bent. Flexing of the wires may cause them to bend and sometimes vibrate, resulting in wire fatigue at the base, causing breakage. Using a brush in excess of its maximum safe speed may damage the workpiece and, most importantly, harm the operator and those around him.

In truth, an industrial brush will perform its best when it is exactly the right size and type for the job, operated at the highest safe speed with the lowest possible pressure.

What follows is a brief explanation of some typical industrial brush styles, their sizes and uses. Finishing remains one of the most labor-intensive elements on the shop floor today—but knowing which brushes go with what application can help squeeze more efficiency out of the operation and, ultimately, produce a better product.

Wheel Brushes

Standard Wheel Brush. As the most widely used, the standard wheel brush's most popular diameters are 6 and 8 inches, though they do come in sizes anywhere from 3 to 15 inches, depending on the maker. They also come in various wire sizes depending upon the workpiece and the type of finish desired. The wire fill is invariable-crimped, which helps make the wires stand apart from each other; this absorbs flexing and vibrations, and helps prevent wire fatigue and breakage.

Most wheel brushes come with a 2-inch arbor hole. Adapters are inserted into these holes to go on shafts ranging from 1/2 up to 1 inch. Most manufacturers offer wheel brushes in heavy-duty-wide-face and super-duty-extra-wide-face wheels.

When comparing brushes, pay attention to the length of trim, which is the length of the wire from the hub, and also the running face width, or width of the brush during operation—normally a different dimension than when the brush is taken out of the box. To extend tool life and improve cutting action, reverse the brush from time to time to run it in an opposite direction.

As with all brushes, a standard wheel brush should be operated at the highest possible safe speed within its quoted safe speed limits and the lightest possible pressure between the work and brush face. Consider wheel diameter when determining optimum surface speeds. With larger wheels, it takes less rpm to attain more surface speed. For instance, with a 3,450-rpm motor, the surface speed of a 4-inch brush has a speed of 3,600 linear feet per minute while a 6-inch brush has 5,400 lfm; a 10-inch-diameter brush would run at 9,000 lfm.