Above: A single Norton Rapid Finish coarse grit convolute wheel can be used to both grind and finish a workpiece, like this piece of carbon steel.
March, 2025- “It’s been a long time since there have been any developments in the convolute wheel until now,” claims Mike Radaelli, senior product manager of non-woven abrasive products for Norton|Saint-Gobain Abrasives. He is referring to the newest addition to the company’s Rapid Finish line: the Norton 60 grit coarse convolute wheels, which feature a patented Norton Clean Bond resin technology. Clean Bond uses a hightemperature resin that produces smear-free finishes and extends the wheel’s service life.
Approximately three years in development, Norton Rapid Finish coarse grit convolute wheels are the result of internal laboratory research and customer field testing to determine the exact blend of grit to achieve a better cut rate while delivering a desired finish all in one coarse wheel.
“Customers told us they were looking for ways to reduce their manufacturing steps.
That was the genesis for the new convolute wheels,” recalls Radaelli, who has been with the company for 35 years. Users can perform grinding and finishing with the same wheel “it’s more efficient,” he says.
The new Rapid Finish coarse grit convolute wheels went through several full manufacturing runs. After each one, “we took the product to the field to confirm that the performance was consistent from run to run,” reports Radaelli.
APPLICATIONS
“Convolute wheels have been around for more than 70 years,” says Radaelli. They are used for medium pressure and finishing applications such as deburring, blending, polishing and decorative finishing all processes that are common in the metals fabrication sector. Norton Rapid Finish abrasive products are also used in the manufacturing of aerospace, automotive and medical components. Convolute wheels are suitable for a range of materials including titanium, carbon steel, Inconel, aluminum, stainless steel and soft metals.
Radaelli offers an example of a convolute wheel application: cast turbine blade. “After the cast is cut off, the operator uses a coated abrasive to grind the cast down. Then the Rapid Finish coarse grit convolute wheel is used to smooth out the turbine, remove all the edges and blend in a precise radius. For aerodynamics, the radius must meet very tight tolerances. That’s the convenience of this new product. It can put in the radius and then blend the finish all in one coarse wheel,” he explains.
ONE DIRECTION
The convolute wheel gets its name from the manufacturing process of rolling longitudinally (wrapping) non-woven abrasive material around a center core, bonding the layers together to create a wheel. Because the non-woven material is rolled, convolute wheels must always run in the direction of the wrap indicated by an arrow usually printed on its side. If the wheel is run in the wrong direction, the non-woven material may delaminate from the center core. “Norton Rapid Finish convolute wheels feature the directional arrow printed on the side of the wheel as well as etched into the center of the core,” notes Radaelli.
Fabricators may be accustomed to seeing gray convolute wheels that are very hard, for general purposes such as blending a weld bead or applying the #4 finish to the front of a refrigerator door panel. Rapid Finish coarse grit convolute wheels, in contrast, are green and soft like a sponge. Norton introduced a color-coding system for its products to help operators easily identify one from the other. “The green color is a point of differentiation. And these wheels are soft; I can press my finger into it even though it’s coarse,” Radaelli explains.
Rapid Finish convolute wheels are available in 6-, 8- and 12-in. outside diameter with 1-, 3- and 5-in. IDs, in widths from ½ in. to 36 in. “We can also cut [the wheels] to specific customer widths, upon request,” says Radaelli. The company stocks semi-finished goods, known as logs. These 36-in.-long logs can be sliced to any width. Rapid Finish is available in a variety of densities and in a range of grits beyond the latest coarse offering.
SMEAR CAMPAIGN
Conventional abrasive products can cause smearing on a workpiece because of the heat that is generated during the grinding or finishing process. The heat expands the abrasive grain, which then leaves only the coated fiber. Continued use and heat exposure can cause the binder coating of the fiber to break down and melt; that residue ends up on the surface of the workpiece.
In contrast, the Rapid Finish coarse grit convolute wheels use a proprietary technology to create Clean Bond high-temperature resin. “This enables the wheel to withstand higher speeds and minimize smears on the surface finish. This means the operator can reduce the number of finishing steps and minimize rework—as well as costs— associated with additional finishing. These features can help increase productivity on the fabrication shop floor,” notes Radaelli. For operators who use water or other coolants in their process, the Rapid Finish wheels’ mesh is waterproof, washable and non-loading.
The surface of a carbon steel workpiece before finishing.
The same piece of carbon steel after finishing with the Norton Rapid Finish coarse grit convolute wheel.
OPERATOR FRIENDLY
Early feedback from Norton customers who performed field tests on the wheels were positive. Users cited several benefits. The non-woven material is significantly lighter in weight than competing brands, minimizing vibration and chatter. “Because of the nylon and resin design, there is less bouncing of the wheel, which means better ergonomics for the operator,” explains Radaelli.
“This lightweight design also means the wheels are more forgiving, and able to mitigate the various pressures applied by operators. There is less probability of changing the geometric shape of the part,” he adds. Such quality control makes the product ideal for tight tolerance applications like aerospace parts.
Some users also reported improved processing time when using the new wheels, in some cases 50 percent less time to finish. Material wear is also reported to be 7 to 10 percent improved with less shredding. “One customer translated this wheel wear into a 33 percent improvement in life,” says Radaelli.
Convolute wheels must always run in the direction of the roll, indicated by an arrow. The Norton Rapid Finish coarse grit convolute wheel features the directional arrow printed on the side of the wheel and etched into the center of the core.
EXPERT SUPPORT
Norton staffs a team of expert technical salespeople across North America. “Our new hires attend 32 weeks of product training at our facility in Worcester, Massachusett s, and at our production sites,” says Radaelli.
With the one-wheel grinding and finishing abrasive product, Norton may have reinvented, or at least improved upon, the convolute wheel. “When we get the coarse wheels into the hands of the operator, they say ‘Wow, it’s doing it faster and with great quality.’ The product sells itself,” says Radaelli.
Norton | Saint-Gobain Inc, 800/551-4413, nortonabrasives.com
