There will be a lot of success stories coming out soon featuring hybrid additive/subtractive machine technology. Still in its early development stages, hybrid machine technology is carving out—after carefully building up layer by layer—examples of complex parts, large repaired workpieces, and molds with process-enhancing conformal cooling channels designed in. Hybrid is showing that there’s more than one way to reduce cycle times and boost the bottom line as long as the total cost of manufacturing processes is considered.
With their recent offerings, major machine tool builders are signaling that hybrid technology is more than an innovative extension of their manufacturing capabilities. Rather, it’s a competitive necessity. And they are answering the challenge with a growing list of machines that marry additive manufacturing (AM) processes with proven, well-established subtractive machining platforms to produce parts complete on one machine. You might call hybrid machines “Multitasking Plus.”
AM, which began making plastic parts more than 30 years ago, has seen working envelopes grow and the addition of metal parts. This has been made possible through adaptation of the two principal delivery approaches, directed energy deposition (DED) and powder bed fusion (PBF) technology. Akin in many respects to laser welding, both DED and PBF approaches are carving out roles for AM technology, working within a well-defined scope of work.
PBF-based hybrid machines are well suited to manufacturing molds with fewer components and process conformal heating/cooling channels and smaller, complex parts that formerly could not be produced. DED-based hybrid machines are excellent choices for larger metal parts and repair of critical aerospace, medical, and oil field workpieces. (For a complete discussion of the technical underpinnings of hybrid AM technology as well as a trip through its arcane alphabet world, see “The Pluses and Minuses of Combining Additive & Subtractive Machining,” Manufacturing Engineering, July 2017).
Moldmaking Returns are Impressive
“Growth for hybrid AM in moldmaking is limited only by the ability of customers to think beyond designing parts in terms of conventional machining,” said Tom Houle, director of Lumex North America, Matsuura Machinery USA Inc. (St. Paul, MN). “We have to work with them to identify how the part or component of a mold, for example, can be improved by hybrid additive/subtractive technology.” Matsuura’s two hybrid powder bed machines, the Avance 25 and Avance 60, use Matsuura high-speed vertical machining center platforms to build and finish machine parts.
Hybrid AM is already a game-changer for the moldmaking industry with impressive potential,” said Houle. “A customer I worked with recently—a project tool maker—saved $5.5 million for the end customer over three years on one part of a 24-part component in the mold for that project. The potential across multiple components on each mold—24 parts across 24 molds—is significant,” said Houle.
“With our hybrid AM, the moldmaker can make components 24/7 untended. CAD modeling can create conformal cooling through simulation of thermal modeling and weight reduction can be achieved. When the final parts come out, they are very nearly finished with complex designs including deep ribs and pockets and the complex geometry for conformal cooling channels. They will enable injection molding that runs 40–50% faster than traditional straight line cooling with a 30–50% improvement in tool life while reducing cycle times. Powder-bed hybrid AM machines can deliver faster cycle times, faster moldmaking times and potentially eliminate the iterative mold grooming and tweaking processes needed because you can do most of the things up-front that typically had to wait until after testing the mold,” said Houle.
What Comes After the Low Hanging Fruit?
Machine suppliers of DED-based hybrid machine technology agree that repair and specialized metal deposition applications are the first and most obvious targets for the technology. According to David Fischer, lathe product specialist, Okuma America Corp. (Charlotte, NC), the usual suspects for Okuma’s laser metal deposition (LMD) technology include aerospace, blade tip repair for turbines and agricultural applications for nonrotating parts, as well as oil patch downhole components that need material welded on to them. Okuma’s MU-8000V Laser EX LMD hybrid machine supplies powder from nozzles and performs laser melting and bonding to parent material. This allows for various types of materials to be combined and layered in addition to the possibility of 3D fabrication and cladding.
“The MU-8000V gives us the ability to control how much material—especially how much expensive or hazardous material—is deposited and where it’s deposited to achieve a desired result,” Fischer said. “A lot of what we’re seeing is customers limiting the amount of expensive material used. Depending on the purpose, they’ll put down enough for corrosion or wear resistance just where they want it and use a lower cost material for the balance of the application. In a European application for hydraulic shafts, they wanted to get away from chroming the parts because of the hazard of working with chrome. They’re going to laser deposit a hard material instead of chrome, machine it, grind it and put it into service.”
Okuma’s MU-8000V is built on a machining platform that features Trumpf laser disk technology exclusively. “It gives us flexibility in controlling the beam shape over a wide range of power settings, whether using 200 W or less for fine detail or the entire 4 kW for heavy cladding. The disk laser oscillator can handle up to six machines. If you’re welding with a robot laser, you’re using the laser 100% of the time whereas with an EX hybrid machine you’re using the laser 20–25% of the time. The efficiencies are obvious,” Fischer said.
Just because hybrid machines have a unique ability to produce complex parts doesn’t mean they should be used in every case, according to Fischer. “In another case, when a customer wanted to lay up a part from scratch, I recommended against it. Hybrid AM isn’t a substitute for manufacturing a part where simple machining can do a faster, better job.”
Highest Density Metal Parts
OPM Metal 3D printers from Sodick Inc. (Schaumburg, IL) combine a rigid linear motor, high-speed 45,000-rpm mill and a 500-W laser powder metal bed AM unit to achieve a 99.99% melting ratio and the capability to produce highly dense parts, according to Evan Syverson, additive business development manager. “With the integrated high-speed mill, the workpiece is regularly machined throughout the printing process to achieve the greatest possible finish, even on many hard-to-reach internal structures,” he said. It also eliminates the need for postprocessing.
Sodick’s two OPM metal 3D printer models, the OPM 250L and OPM 350L, are a natural extension of Sodick’s expertise in moldmaking as a manufacturer of sinker EDMs and high-speed machining centers, as well as injection-molding machines. Combining powder metal bed additive and subtractive milling technology can change manufacturing complex molds in dramatic ways. In one example, two OPM 250L Metal 3D printing machines replaced a large-scale production lineup that comprised three machining centers, six wire EDMs, six sinker EDMs, four grinders and a mill. And it produces the same in half the time, according to Sodick.
Typical applications for Sodick’s OPM Metal 3D printers include reducing the number of components for molds and printing conformal cooling channels for faster and more efficient injection molding of production plastic parts. “Plastic injection molding is very dependent on cycle time to achieve the required production volumes,” Syverson explained. “The biggest holdup is the cooling time. With conformal cooling instead of straight water lines, cooling time can be reduced as much as 40–60%, hot spots can be prevented, and accuracy of parts is increased. Our OPM 3D print process is pretty straightforward. We can control the number of layers deposited from 10 to 100 or 200 per cycle and control the intervals between machining. The high-speed mill removes metal with small E25 or HSK tools. Because we’re printing to near-net shape, only light-duty material removal is required. The result is the highest possible surface finish in the industry,” he said.
Hybrid Technology Extends Multitasking Reach
For Brian Papke, chairman, Mazak Corp. (Florence, KY), hybrid technology represents a further extension of its multitasking machine technology. “When you walk into our Chicago Technology Center, you will see the five levels of multitasking available in Mazak technology spelled out on the wall—with just enough room to add a ‘plus one’ for additive technology,” said Papke. “We started with drilling, milling, boring, tapping, five-axis technology, broaching and grinding, moved up to gear cutting, skivving and hobbing, cryogenic machining, and our Orbitec machine. We can see a definite role for friction stir welding; another additive technology that shows promise is hot wire laser deposition.”
Mazak’s approach to implementing new multitasking hybrids is to develop partnerships that allow it to move quickly in adapting technology. Friction stir welding is a good example. When these machines are fully developed, they will be introduced as their own brands rather than simply extensions of existing Mazak machine models. “Developing some really nice partnerships is allowing us to move forward in technology development rather than reinventing the wheel.”
Mazak’s new Integrex i-400AM hybrid multitasking machine, for example, is especially well suited for small-lot production of difficult-to-cut materials such as those used in the aerospace, energy and medical industries. With the additive capability, manufacturers can generate/clad near-net-shape component features, then complete them with high-precision finish machining operations—as well as laser mark the parts if needed.
In operation, the Integrex i-400AM melts metal powder using a fiber laser. Cladding heads (additive manufacturing nozzles) apply the molten material layer by layer, each of which solidifies as the desired shape grows. Plus, the system can join different types of metals to one another, a capability beneficial for the efficient repair of worn or damaged existing components, such as aerospace turbine blades.
On the multitasking machine side, the Integrex i-400AM provides full five-axis capability to process prismatic parts from solid billets or castings (chucked or bar fed), round parts, highly contoured parts and now those with features built via additive technology.
Three Complete Process Chains
At DMG Mori (Hoffman Estates, IL), the focus is on “process chains” for hybrid machine technology. The company has adopted three complete process chains for powder bed and powder nozzle additive manufacturing. The Lasertec 3D hybrid series machines, which provide a combination of laser deposition welding and five-axis milling, are the basis on which the company established its full-line approach to additive manufacturing. The Lasertec 65 3D hybrid has a maximum X-axis travel of 28.9″ (734 mm); Y-axis travel of 25.6″ (650 mm) and Z-axis travel of 22″ (559 mm). The Lasertec SLM series expands the machine range to include the powder bed method using selective laser melting for producing small, complex filigree parts with flexible use of different materials. An intelligent powder module concept allows the change of material in under two hours.
“Both manufacturing technologies complement each other ideally in our product range,” said Patrick Diederich, responsible for the Advanced Technologies division. “The powder bed process is of particular importance. The technology has a share of 80% in the market for the additive manufacturing of metallic components.” Combining laser deposition welding and machining on a single machine platform was introduced by DMG Mori in both the five-axis Lasertec 65 3D hybrid and the Lasertec 4300 3D hybrid. The concept combines laser deposition welding and six-sided turn/mill machining, and both machines are designed for manufacturing comparatively large components such as turbine components.
DMG Mori is actively advancing Industry 4.0 with its “Path of Digitization” and its intelligent software solutions. These include the intuitive user interface CELOS, which is already used for the Lasertec 3D hybrid machines. Realizer, a DMG Mori company, has created RDesigner especially for the powder bed machine. It will be integrated into the CELOS interface in the future. “The capture and management of data and the use of user-friendly apps offer a great opportunity for supporting work preparation and production processes in their entirety,” said’ Diederich. “Digitization and additive manufacturing go hand in hand and will tap great potential. It enables a transition to individual mass production in industrial serial production. Spare parts, for example, no longer need to be held in stock. They can be printed virtually on demand,” he said.
Hybrid Plastics Machines in the Works
IMTS 2018, to be held in September, will be an important venue for viewing the latest hybrid technology, as major builders are readying a host of new machines. At IMTS 2016, Hurco Co. Inc. (Indianapolis, IN), introduced a beta version of a 3D print head designed to be integrated with its vertical machining centers running PLA plastic filament. “The print head is designed to be manually inserted into the spindle of the machine,” said Hurco’s Fred Gross. “A newer, streamlined version weighing about one-third of the 20 lb [9 kg] beta head is being developed. In addition to being lighter, it will produce a better quality part, because, unlike the beta version, it will be electrically interfaced to the machine.”
The print head will have interchangeable tapers for CAT 30, 40, and 50 and HSK 63 interfaces. Programming is done on Hurco’s Winmax desktop programming software, a free downloadable package that enables designing a solid model as well as providing a program to run the machine. “Currently, we support the plastic PLA filament, but nylon and ABS can be run at the same temperatures, and we’ll be able to support larger filament than the current 1.75-mm PLA filament,” he said.