Groovy kind of process: People & Companies

When machining, specialty materials always have come with unique problems and solutions. With grooving specifically, working with materials like titanium alloys and heat-resistant superalloys is no exception. Experts have different suggestions for successful grooving but agree that it takes experience, the right tooling and patience.

Grooving falls into its own category in manufacturing. The process creates good clearances, offers flexibility and generates features that no other tooling can. Grooving even can run multiple operations with a single tool. The downside is that grooving doesn’t allow the same mechanical advantage as other methods. For example, a square tool is used to cut a round object that’s rotating quickly. This makes it more difficult to reliably hold the tool, perfectly line it up with the centerline of the rotating material and achieve a “perfect” groove. These challenges become even larger when specialty materials are introduced.

Physically Speaking

The physical differences among titanium alloys, HRSAs and “standard” materials, such as stainless steel and aluminum, go beyond what you might see if you look at them. Titanium alloys have high levels of nickel and chromium while HRSAs are exceptionally good at keeping heat away from material — a property that’s great in some situations but disastrous at a machine shop.

Coolant sprayed from channels within the tooling helps keep a tool from overheating. Image courtesy of Iscar USA

Due to these physical differences, titanium alloys and HRSAs cannot be cut reliably with the same tooling, speeds or even techniques as stock 6061 aluminum, for example. Sometimes people don’t understand these differences, so education can be hard. To address the first part of the equation, machinists need to combat the heat resilience of these materials.

Travis Coomer, national key account manager for Tavares, Florida-based GWS Tool Group, said it all comes down to how much heat is generated, where it goes and how it’s handled. Controlling heat is one of the main focuses of machining. That’s largely why feeds, speeds and tooling considerations matter in the first place.

“If you’re cutting HRSAs,” he said, “then the heat has only two places to go: the chip or the tool that is cutting.”

Machinists know that heat in a tool is rarely a good thing. It wears out tooling quicker and hurts machine performance. When tools wear out, they need to be replaced, which takes time and costs money.

While titanium alloys don’t feature the same heat resistance as HRSAs, they are equally as difficult to machine. Because the material is so much harder to cut due to the added nickel and chromium, extra heat and force are put into the grooving tool, shortening its life.

Tool chatter is another common issue while machining titanium alloys or HRSAs. With harder materials, more vibration is sent into the cutting head. This alters the precision of grooves and might lead to creating parts outside customer specifications.

Upgrading Tooling

For these problems, a best practice used across the industry is to opt for higher-tech tooling. Since it will be cutting into the material, shops prefer to use stronger, more durable, heat-resistant tooling.

Steve Vanderink, national product specialist for grip products at Arlington, Texas-based Iscar USA, pointed out tooling changes that improve the ability to groove specialty materials. He mentioned switching to submicron carbide tooling, thin physical vapor deposition coatings, high-sheer chipformers and coolant upgrades.

These upgraded tooling changes solve the problems associated with grooving titanium and HRSAs. Heat is diverted away from the tool, which allows cutters to last longer, produce more reliable results and reduce overall downtime. The trade-off is that these tooling changes cost a lot more than a traditional grooving tool that a shop might use to cut aluminum. It also means that shops without these tools can’t consistently groove specialty materials like titanium and HRSAs — creating a divide with shops that offer grooving.

All these technical advances help prolong tool life. Submicron carbide and PVD coatings improve the cutting ability and physical characteristics of tooling, permitting a tool to wear slower when it works on difficult materials like titanium. Better chipformers keep hot chips away from the material and tooling.

High-quality tooling used to cut HRSAs might have built-in holes and channels to support flowing coolant during machining. Keeping heat away from the tool and out of the part is a big focus in creating a good groove. With the introduction of coolant that was supplied directly through the cutting tool, heat became better controlled, letting tools last longer.