The latest claim from heavy-duty coated flap wheel and non-woven disc manufacturers is that customers willing to spend a little more can get double the average life from new abrasive products. Several manufacturers reported this year that heavy-duty wheels rough-grind welds and slag in the same time that bonded wheels do, but will also finish castings and forgings to satisfactory, machine-ready finishes.

A typical finishing wheel for cast iron or steel is a cloth or fiber disc. Extra-heavy-duty non-woven discs can save hours on certain applications, according to Bob Zinck, vice president of sales and marketing for Acadia Technologies, an abrasives distributor in Harvard, Mass.

"We take samples to customers and run them on medium roughing and finishing applications. Very often, the customer says he has another job on which the discs will produce at nearly 2-to-1 over his old discs, saving hours and even days on complete jobs," Zinck said. "They can outperform most discs out there. If you're cleaning dumpsters of rusty railroad cars, they'll grind the surface down ready to paint in one application."

A typical disc is a 7x7/8, 36-grit. They run as coarse as 16-grit. The extra-heavy-duty discs he stocks are the third generation using the heavy, blocky abrasive, Zinck said, and have been available for about six months.

"I like to sample these out because a job always comes up that it's perfect for," he said.

According to Barry Cole, of Carborundum Abrasives in Worcester, Mass., the newest heavy-duty flap wheels offer savings because they not only cut finishing time due to their aggressive cutting attributes, but they also eliminate the need for changing a roughing flap wheel for a finisher.

"The key element is flexibility. In metal removal, standard fiber discs require changing. We consistently see 40 percent longer life than standard flap wheels," Cole said.

Mark Jeffries, a sales manager at Machine & Welding Supply, based in Dunn, N.C., has two customers using coarse, 24 and 36-grit heavy-duty Carborundum flap wheels.

"I can say definitely customers are saving time with the [wheels], and I can vouch for the performance. We have moderate to good success with several customers. A company that makes prison beds is [roughing and finishing] with a 36-grit. The beds are all angle iron and must be smooth at all corners," Jeffries said.

Another customer grinds casket-vault steel frames, using 24-grit because he has lower surface finish requirements.

"He has only four or five people in a labor intensive operation. The product lasts longer and cuts faster, so it's a better value," he said. "The product is more expensive, in general, and abrasives are very price sensitive. You still have to convince customers of the value in heavy-duty products. You still have to earn the sale," Jeffries added.

Denray Machine Co. of Mt. Vernon, Mo., makes particle collection tables for the woodworking industry. According to operations manager Steve Cooper, the company roughs and blends welds on cold rolled steel tabletops with a 5-inch, 60-grit, heavy-duty flap wheel. They have always ground welds in one operation, but heavy discs last much longer, he said.

"Aside from leaving a radius on an inside corner, the [heavy-duty flap wheel] is generally as good or better than our previous product," Cooper said. "It's bigger and lasts longer and we don't have to change it out as often. That definitely saves time. On a cold rolled table top, we used two of the old wheels per top. Now, one heavy-duty does one top and still has abrasive left," he said.