Welding Digest

Today’s grinding applications require highly productive, long-lasting abrasives suitable for a range of materials. To address these needs, abrasives manufacturers must continually research, develop, and innovate. Recently, abrasives have been taken to another level with the development of engineered shaped ceramic grain, which improves performance on carbon steel and challenging materials such as aluminum, Inconel, stainless steel, and titanium. 

A history on abrasives development sheds light on what led up to the development of the new engineered shaped ceramic grain. Traditionally, grinding wheels with fused aluminum oxide grain were used to remove welds or bevel parts on carbon steel. Next, zirconia-alumina grain was developed and fiber discs became a go-to for weld removal. However, even with the advanced zirconia grain, high forces were needed to keep the grinding points sharp, so ceramic grain came on the scene. Ceramic grain requires less force and offers longer disc life. Improving abrasive products performance even further, ceramics and topcoats (i.e., grinding aids) were developed.

Teamwork Matters and Testing Counts 

Seeking long product life, cut rate, and grinding efficiency, applications experts along with research and development, the sales force, and suppliers collaborated to develop engineered shaped ceramic grain to be used in coated abrasive products.  

First, the team defined key performance indicators based on the needs and desires of the market. Shaped ceramic grains require an entirely different manufacturing process. Therefore, the team brainstormed grain shapes that would be appropriate to manufacture, be processable in coated abrasive production, and most importantly, be highly efficient in metal removal. The top contending shapes were then manufactured on a pilot scale. These prototype grains were quickly screened in existing abrasive product architectures. After a few cycles of grain evaluation, an engineered shape stood out with razor-sharp tips.  

With the grain shape determined, the next challenge was designing new coated abrasive products that would optimize performance with the grain. Product development consisted of many iterative learning cycles to continuously improve product performance. The team designed, manufactured, tested, and evaluated prototypes. What was discovered would be used to start the next cycle over again: design, manufacture, test, and evaluate. More than 100 designs were evaluated, and multiple patents came along the way, to get the most out of each component of the products until they were meeting or surpassing all performance indicators. The chosen design was tested by many customers, both domestically in the United States and abroad. A few more design cycles later, the abrasives featured an engineered shaped ceramic grain in fiber discs, quick-change discs, and belts and met the internal performance metrics.  

Engineered Shaped Ceramic Grain Highlights 

New engineered shaped ceramic abrasive grains have been formulated to avoid the common challenges conventional ceramic abrasives face when grinding difficult materials. Optimizing both abrasive grain and abrasive architecture results in longer life, especially on hard-to-grind materials, achieved with less heat buildup, higher cutting efficiency, and broader versatility. Each engineered shaped grain is precisely dimensioned to a patented shape to ensure uniform, efficient cutting and predictable fracture behavior. Meanwhile, the unique star shape comprising nano-scale, highly pure alumina crystals promotes self-sharpening as the grain microfractures during grinding.  

In contrast, conventional grains have unpredictable fracture behavior and are either too dull to avoid fracture, leading to tip erosion, rubbing, dulling, and metal swarf adhesion, or they are too weak to fracture on the desired microscale, leading to unpredictable, large-scale fracture, fast grain wear, and poor abrasive product life. 

Architecture Details 

The innovation behind engineered shaped ceramic grain abrasive products is not just the shaped grain but also the optimized abrasive design. The layered architecture of backing, resins, grains, and grinding aids has been constructed to further promote efficient grinding with the engineered shaped grain. Grains are adhered to the backing in a precise spatial density to control the force per individual grain. This tuned force per grit leads to efficient self-sharpening, resulting in longer life at lower energy consumption. To fully achieve the efficiency of both the individual grain and the group as a whole, a series of innovations were developed and established by the team, covering everything from product design to product making. 

Grinding Performance 

The abrasives improve operator comfort, enable high productivity, and enhance grinding efficiency. By combining a self-sharpening, novel-shaped grain with a precisely designed abrasive architecture and the highest grain orientation, the RazorStar™ grain offers ideal grinding performance with belts, fiber discs, and quick-change discs. 

The belts are versatile; capable of cool cutting; and suitable for automation, robotics, and power pack or off-hand metal removal applications. They are suited for applications requiring medium to high pressure where the goal is to quickly remove a high amount of metal with as few abrasive belts as possible. The belt’s cool grinding is suited for sensitive alloys and hard-to-grind materials where metal burn must be avoided. The efficiency of the grain to cut vs. plow material, combined with the grinding aid in the resin coating layers, which produces additional lubrication, results in long belt life and protects against workpiece discoloration.  

The fiber discs use the same technology as the belts and provide beveling, weld removal, and stock removal. The fiber discs are a best tier solution, according to the company’s abrasives classifications, that work on typical carbon steel welds and are also suitable for stainless, superalloys, and other exotic materials. Due to the engineered shaped grain and the abrasive architecture, one disc is typically needed for a range of materials. 

Another advantage of the efficient grinding behavior of the fiber discs is operators can apply less pressure to the work. The reduced pressure may also extend the life of the angle grinder. 

On the YouTube channel for Norton Abrasives (youtube.com/@NortonAbrasives), videos about RazorStar™ may be viewed. 

Conclusion 

In closing, this technology-based story reviews the development behind the scenes of bringing these newly developed coated abrasives products to fruition. 

The article was submitted by Norton | Saint-Gobain Abrasives (nortonabrasives.com), Worcester, Mass., for the American Welding Society.