Page 38 - MetalForming September 2017

Flap Discs
When working with thinner materials, flap discs are often a good choice. They provide reliable grinding action, while also allowing for more delicate blending and finishing work.
...can save time, money and material when working with thinner material.
best for more aggressive, higher-angle grinding, between 15 and 35 deg.
Before selecting your disc, consider which type will be best for helping achieve your surface-finish require- ments, desired aesthetics, and time, productivity and efficiency require- ments, while minimizing labor and consumable costs.
Selecting the Grain and Disc Size
Generally speaking, to ensure the best possible finish, choose the highest grit possible that still gets the job done.
In addition to standard-density flap discs, high-density (jumbo) flap discs have more cloth on them, making them thicker, softer and longer-lasting. High- density flap discs are the best choice for grinding on curved or irregular surfaces.
Flap discs are made in different sizes, too, ranging from 2 to 7 in. A 2-in. disc can essentially replace a blending disc, and gives an operator as much as 15 times the use. Reducing the number of product changeovers can have an imme- diate and dramatic effect, and signifi- cantly lower the overall cost of use.
BY RICK HOPKINS AND RON MCCARTHY
Flap discs, when used for appli- cations with thinner materials, can reduce the risk of removing too much material while reducing process costs and time. However, in order to select the best flap disc for the job, features, performance charac- teristics and job requirements must be considered.
Flap-Disc Basics
When working with thinner mate- rials, flap discs provide reliable grinding action, while also allowing for delicate blending and finishing work because of their soft feel. The flap discs feature
Rick Hopkins is senior product man- ager-welding and fabrication for Weiler Abrasives Group, Cresco, PA, 570/595- 7495, www.weilercorp.com. Ron McCarthy is director of marketing for Oliver H. Van Horn Co., New Orleans, LA, 800/800-7070, www.ohvanhorn.com.
coated abrasives that adhere grains— the same grain types found in bonded abrasive—to a backing cloth, typically a cotton, polyester or blended material. This abrasive cloth is then cut into smaller flaps and layered radially to form the flap disc.
How a flap disc performs is largely related to the abrasive material used and its grit size. Three primary cutting grains used on flap discs include alu- minum oxide, zirconia alumina and ceramic alumina. The flaps wear away as the grains deplete, which exposes fresh and sharp grains below. When used properly, a flap disc essentially can be used until the cloth is nearly worn down to the back plate.
In general, flap discs are designed for use on right-angle grinders at angles from5to35deg.AType27flapdiscis best for finishing and applications requiring lower grinding angles ranging from5to15deg.AType29flapdiscis
36 MetalForming/September 2017
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