May 2018 Issue
Toc

Let’s take a walk out to the welding area. After you’ve listened to your top prep guy, Bob, griping yet again about his neighbor’s barking dog, and the welding department supervisor, Mary, telling you for the third time how her kid threw the game-winning touchdown pass last weekend, stick your head into the trash can. No, this isn’t a means to avoid friendly conversation, but rather a way to see how much money your company wastes each day on abrasives.

Peering down into the bottom of that trash can reveals a pile of partially used grinding wheels. Chances are, you’re thinking, “What the … (insert your favorite pejorative term here)?” They’re only a couple bucks apiece, but still, why are perfectly good wheels being thrown away?

According to Saida Guerra, grinding and cut-off wheels product manager at Norton | Saint-Gobain Abrasives, this isn’t an unusual sight. “There are several reasons why someone might dispose of a grinding wheel prematurely,” she says. “Maybe they’re using a 9-in.-dia. wheel to get into a tight area on a workpiece. As soon as the wheel wears down to around 8 in., it can’t reach the part feature anymore so the operator throws it away. Or perhaps the operator is pushing too hard and the wheel loads up a little bit. The perception is that the wheel is worn so they will reach for a new one, even though there’s plenty of life left on the old one.”

Attitude Adjustment

Part of the solution is employee training. Unlike the high-tech CAM systems and expensive tooling found on CNC press brakes and laser cutters, the welding area often gets the short end of the stick when it comes to its training budget.

“It’s just grinding and welding,” after all. The result of this attitude, however, is a steady trickle of consumables cash flowing down the drain, small enough to fly under the radar of even the most fiscally minded manufacturing company but sufficient enough to hurt the bottom line.

Fortunately, Norton | Saint Gobain Abrasives, Walter Surface Technologies Inc. and other abrasives suppliers are happy to come onsite for lunch-and-learn events, safety seminars and an entire day of classroom training. Attendees will learn everything there is to know about abrasives, including wheel size and abrasive selection, grinding safety, the effect of grit size, bonding principles and – most importantly – how to get the most out of consumable products.

They will also learn about advanced abrasives.

“Oh, those things,” you say. “We don’t grind any superalloys or hardened materials here, nor do we remove huge amounts of material. Why would I spend three times as much for what just ends up in the trash anyway?”

Simple Reasons

Not so fast, says Guerra. There are a number of good reasons to use advanced abrasives, such as ceramic aluminum oxide and zirconia alumina.

“It’s very simple, really,” she explains. “There are three things to consider about grinding wheels: abrasive life, cutting speed and operator comfort. That’s it. An advanced abrasive gives you the best of all three.”

And what about the price? Here again, the answer is simple.

“Because a top-tier abrasive lasts so much longer than the basic aluminum oxide wheels everyone is used to, you’re going to use far fewer of them,” Guerra explains. “What’s more, metal removal rates are often five to six times greater than aluminum oxide and comparable low-cost abrasive products. They also offer a much better feel and less downtime spent on wheel changes. There’s simply no reason not to use one of them.”

Patrick Lapointe, vice president of research and development at Walter Surface Technologies, agrees. “You can definitely enjoy a significant productivity improvement with a premium abrasive product. Compared to aluminum oxide, a ceramic alumina or zirconia grain not only lasts substantially longer, but it stays consistent during the life of the product. There’s no performance drop after the first few minutes as there is with traditional abrasives.”

There are several reasons for this. Ceramic alumina and zirconia alumina are both harder and tougher than their alumina oxide cousins. The microstructure of these high-performance abrasives also makes them more friable, meaning they self-sharpen during use. This not only increases their metal removal capabilities, but the presence of continuously fresh abrasive helps them do the job even better, according to Norton’s Guerra.

Not One Size Fits All

Lapointe says there’s more to the story than the type of abrasive, however. “That’s a big part of it, but there are many other factors that affect the life and performance of these products. Sometimes, you come across an application where the customer is using a high-performance ceramic-grained wheel, but you can actually achieve better results with a zirconia alumina mix.

“Another factor is the exact formulation of the wheel,” he continues. “This includes how much and what type of resin is put into the mix, the abrasive backing, the specific mix of abrasives, the wheel construction and a host of other factors.”

The takeaway here is that shops should experiment with different types and brands of abrasives if they want to find the ideal solution for any given application (and they should always document the results of their testing). This is especially true on high-volume work, with difficult materials or where large quantities of a specific material are fabricated.

“In all honesty, it can be challenging for customers to find the right solution,” Lapointe says. “There are so many products, suppliers and levels of quality to be considered, never mind the fact that the technology is always evolving. As an abrasives company, our job is to stay abreast of these innovations and to work closely with and train our customers. In many cases, we’ve found that a premium-quality abrasive is the most economical and productive offering, despite its higher initial cost.”