by Kip Hanson
Cutting tool manufacturers have begun to embrace a technology that some said would make their products obsolete
Remember all the “experts” who predicted that 3D printing would one day reduce, or even eliminate, machining? Forget about those guys. These are the same folks who said computer-controlled mills and lathes would never replace mechanical machine tools, or that high speed steel cutting tools are just as good as those made of tungsten carbide. Wrong, wrong, wrong.
It should be clear to everyone by now that additive manufacturing (AM) is here to stay. What was once a “prototype only” process—and limited to resin-based prototypes—has evolved into a mainstream technology, able to print an enormous variety of plastic and metal parts for use in aircraft, automobiles, and the human body (to name a few) and do so even in production quantities.
None of that means, however, that subtractive manufacturing (i.e., machining) is going away anytime soon—quite the contrary. While the breadth and complexity of parts made via AM continues to outpace what’s possible with traditional manufacturing processes, printed parts will—for the foreseeable future, at least—require secondary machining operations to counter the relatively poor accuracy and surface finishes generated by most 3D printers.
Because of this, additive and subtractive manufacturing are in many ways the perfect marriage, each supporting the other in ways that no one dreamed of even a decade ago. Perhaps more importantly, 3D printing is opening unexpected doors to greater machining efficiency. Cutting tool manufacturers have begun using it for their own prototyping needs, yes, but they’re also exploring ways to print smarter, faster and more effective milling cutters, reamer bodies and drills, even customized tungsten carbide inserts.
Consider cutting fluid delivery. In his paper “Iscar Enters the Age of Manufacturing,” Iscar technical manager Andrei Petrilin notes that “AM enables the creation of complex internal channels and cavities in cutting tools. These features provide a coolant supply to the cutting zone through the body of the tool. If the tool is designed for machining with high-pressure coolant (HPC), the shape of the channel and its cross-section is a key factor. AM provides the ideal solution for ‘forming’ these channels.”
In addition, “AM enables the creation of cutter bodies that are already equipped with chip gullets, relief surfaces, back drafts and undercuts,” he says. “With traditional manufacturing technologies, these features are created through the application of cutting techniques. In this situation, the use of AM would reduce machining operations and slash cycle time. Further, AM ensures the formation of the required shapes with optimum balance between the body strength and chip evacuation.”
In short, manufacturers have discovered something that 3D printing aficionados have long understood: AM can produce shapes otherwise impossible to manufacture. Because of this, and because metal AM machines readily print tool steel as well as dozens of other alloys, a huge variety of customized tooling is now possible.
Of Olli and oil wells
Sandvik Coromant, for instance, has seen great success with its lightweight, 3D-printed CoroMill 390. Tooling engineers at parent company Sandvik not only printed the indexable shoulder mill from titanium powder, but optimized its geometry to further reduce weight. One of the tool’s notable success story comes from Phoenix-based autonomous vehicle manufacturer Local Motors, which used it together with one of the toolmaker’s Silent Tool adapters to cut machining time on a 3D-printed vehicle chassis (the Olli) by more than 90 per cent.
Another of Sandvik’s commercialized, 3D-printed products offers something that any lathe operator can appreciate: improved coolant flow. “In 2013, we began looking at ways to leverage 3D printing for various tooling applications,” says Mikael Schuisky, vice president of R&D and operations for Sandvik Additive Manufacturing. “One of the first commercial products to come out of that research project was a turning tool insert clamp with tiny internal channels for precision delivery of cutting fluid,” he says. “We’ve also developed methods to print and sinter cemented carbide, and have begun making 3D-printed impellers using Sandvik’s super duplex stainless steel, Osprey 2507, especially developed for applications in the oil and gas or marine industries.”
Seco Tools, which is part of the Sandvik Machining Solutions business area, markets the coolant clamps under the brand name Jetstream. It is an otherwise common tooling item that Schuisky says could not have been produced via conventional methods, but one that significantly improves turning operations, especially when combined with high-pressure coolant. As for the impellers, they are just one more example of Sandvik’s use of AM technology to support the industry’s growing need for high-performance components.
Sandvik is no stranger to the powders used in metal AM. Marketing and communications vice president Lena Berg notes that the company has 158 years of experience in materials technology. It has been producing metal powders for more than 45 years for advanced technologies like MIM (metal injection molding), and has today the widest range of AM alloys on the market. “And with all relevant printing technologies for metals inhouse, such as powder bed fusion (laser and electron beam), binder jetting and stereolithography, Sandvik has well-established expertise across the AM-value chain,” she adds.
“We’ve gained extensive experience with the 3D printing of tool steels, maraging steels, stainless and super duplex steels, high-temperature materials, nickel-based superalloys and titanium alloys, as well as hard and super-hard materials like cemented carbide and diamond composite,” Berg says. “This experience will be quite useful in the creation of new or improved cutting tools or other advanced components.”
E-mobility and beyond
They’re not alone. Kennametal, for instance, recently worked with a European automaker, which was attempting to ream a series of 250 mm (9.84 in.) bores nearly 400 mm (15.74 in.) deep in an electric motor housing. The problem was the weight. “The reamer, had been made via conventional means, would have weighed 25 kilograms (55 lb.), far too heavy for the machining centre’s toolchanger or for an operator to work with,” says Kennametal program engineering manager Harald Bruetting.
He and Kennametal’s Solution Engineering Group leveraged their in-house additive manufacturing capabilities to design and print a lightweight indexable reamer, one equipped with the company’s RIQ reaming inserts and a KM4X adaptor. And because there are few geometry limitations with 3D printing, the tool also features internal coolant channels for improved tool life and throughput. The result? A tool that weighs half that of the original design but is still rigid enough to machine the bores effectively.
Kennametal sees opportunities beyond cutting tools and tooling. Sherri McCleary, director of Kennametal’s Additive Manufacturing business unit, part of the company’s Infrastructure segment, says market analysts expect oil and gas alone to increase its use of AM by 40 per cent annually through 2027. This helps to explain why the Pennsylvania-based toolmaker launched a standalone 3D printing business unit late in 2019, with McCleary at the helm.
“We are focused on additive applications where we can leverage our core capabilities in delivering material properties for demanding applications in wear, erosion, corrosion and high temperatures,” she explains in a recent news story. “As such, we’re delivering additive manufacturing solutions to our customers that include everything from powder metals optimized for AM printing to prototyping services and fully finished production components, and have capabilities in both laser-powder bed and binder-jet technologies.”
McCleary notes that the business is leveraging high performance materials such as Kennametal Stellite 6-AM-K and cemented tungsten carbide to produce 3D printed components for the oil and gas market, power generation, and other process industries where there is high demand for wear performance and/or where operational up-time is critical and down-time is very costly. “Looking to the future, we’re excited to blaze new trails in 3D printing materials and applications while growing the size and scope of our business.” SMT