Page 31 - MetalForming-Jul-2018-issue
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   especially on aluminum. Due to their round shapes, these products provide the same point of contact to the work- piece no matter the angle of approach, allowing operators to manipulate their access angle while still maintaining the same point of contact to the workpiece for a consistent finish in significantly less time than manual finishing. When finishing parts by hand, operators may avoid changing hand positions or tool orientations to work around obstacles for fear of damaging the part.
A smoky haze often lingers on an aluminum part after gas-metal-arc welding. Using a circular flared-end brush in a fine stainless-steel filament, such as 0.006- or 0.008-in. wire, will remove the haze and leave a nice finish. Thinner-gauge wire brushes, well suit- ed for cleaning and finishing thinner material, also are available in larger sizes such as 0.020-in. wire
As with any wire brush, let the wire tips do the work. Applying too much pressure causes the wires to bend, and can lead to wire breakage and prema- ture brush wear. If the brush requires replacement, consider one with a coarser wire or a different brush-trim length. Brushes with a shorter trim length provide a greater ability to remove aggressive materials, while longer trim lengths can improve oper- ator comfort and perform better on irregular surfaces.
2) Mini flap discs, which provide the same benefits as standard flap discs, are ideal for reaching into tight spaces due to their smaller size–2- and 3-in.-dia., with grit sizes ranging from 36 to 120. While a good option for grinding, blending, deburring, cham- fering, edge chamfering and finishing on mild or stainless steel, these discs aren’t an efficient option for working on large surface areas due to their size.
In some applications, mini flap discs can replace small blending discs, as these discs shed cloth and expose new grains to deliver a consistent and aggressive cut rate. They can remove as much as three times the material over the life of the disc as compared to a blending disc. These features save
Circular-flared-end brushes allow operators to manipulate access angles while main- taining the same point of contact to the workpiece, for a consistent finish in significant- ly less time than with manual finishing.
MetalForming/July 2018 29
time and money by minimizing prod- uct changeover.
Angle and pressure are key consid- erations when using a mini flap disc. The Type 27 flap disc, well suited for finishing applications requiring lighter pressure and lower grinding angles ranging from 5 to 15 deg., features a flatter profile. For more aggressive, higher-angle grinding, between 15 and 35 deg., try a Type 29 flap disc with an angled design. When using a mini flap disc, avoid placing too much pressure on the disc, and always use lighter pres- sure when surface finish is a priority. A noticeable drop in sound coming from the tool indicates that the oper- ator likely is using too much pressure.
When using mini flap discs, avoid dwelling too long in one spot. Keep the product moving to avoid gouging or damaging the workpiece. Dwelling also causes heat to build more quickly, which can adversely affect the finish, weld strength and mechanical prop- erties, especially on thinner materials.
3) A 1-mm cutoff wheel, often a bet- ter option than a standard 0.045-in.- dia. wheel when working with thin- gauge materials, reduces surface contact with the workpiece to minimize burr formation as well as heat buildup and discoloration throughout the cut.
Especially on thinner materials, fric- tion and heat are the enemies, and imperfections on the workpiece become more obvious. Using a stan- dard-sized cutting wheel on thin mate- rials can result in heat discoloration and burrs down the cut line, which requires secondary operations for cleanup before the process can con- tinue. With a 1-mm cutoff wheel, that extra time and money spent on sec- ondary cleanup can be minimized or eliminated.
On sheetmetal, thin-wall tubing, small rods and similar materials, 1-mm cutoff wheels provide a precise, fast cut. Because of the thinness of the wheel, these products aren’t well suited to cutting thick materials.
Proper technique also helps mini- mize heat and friction when using a 1-mm cutoff wheel. Just as with other abrasive products, using too much pressure is a common misstep. Use light pressure and consistent move- ment for a cleaner cut and extended wheel life. Also, avoid dwelling in one spot too long to minimize heat buildup.
Finally, with so many options avail- able for cutting, grinding and finishing applications, consult a distributor or product manufacturer to maximize results. MF
Fabrication: Finishing

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