The integration of additive and subtractive enables product designers to pursue product enhancements that could not be manufactured in any other process. At the same time, this combination is reducing the time it takes to prepare for parts production, including acquiring the necessary tooling. Additionally, it is trimming costs associated with tooling and conserving a lot of expensive raw materials typically machined away in strictly subtractive operations.
It’s no wonder manufacturers are taking a greater interest in integrating the technologies.
Machine tool builder DMG Mori recently began incorporating additive manufacturing (AM) to metal-cutting processes that traditionally only used subtractive operations.
The hybrid manufacturing machines from DMG Mori allow the integration of additive (deposition) and various types of subtractive operations without removing the part from the machine. The machines have higher deposition rates and larger envelopes to enable deposition and machining of larger parts.
In one example of hybrid manufacturing, metal AM technology is paired with subtractive technology, enabling each process to work together on the same machine and same part.
The latest iteration here is building hybrids with larger envelopes—that support greater deposition rates and require more powerful lasers, DMG Mori Advanced Solutions CTO Gregory Hyatt said.
Such machines can be leveraged to deposit multiple alloys with alacrity.
“For example, when the workpiece requires a bi-metallic build like Inconel and copper for a rocket nozzle, we can deposit these two compatible alloys in the same build,” he said. This development of methods has also spurred innovation in other areas such as programmable fixturing, laser hardening and subtractive manufacturing processes such as ultrasonic grinding.
“Deposition exerts minimal forces on the part, so minimal support from a fixture is required, but in order to machine without chatter, the need for a fixture returns. DMG Mori has developed programmable and flexible fixturing techniques, which replace the conventional fixture, to support the parts being machined,” Hyatt said.
It has also greatly reduced part-production prep time, the lead time to acquire the necessary tooling and the cost associated with the tooling, he added.
Laser hardening also on tap
Laser hardening, a heat-treating process that hardens the surface of a part, can be used in addition to the additive and subtractive processes.
Surface hardening is traditionally done with induction or flame-hardening methods but can be performed with the same laser used for AM so there is no incremental cost to the machine tool.
While the laser-hardening process has been around for nearly a decade, DMG Mori started combining the use of the same laser for deposition and surface hardening about three years ago.
The company in the last year integrated surface hardening into the scope of “hybrid,” and the benefits are already noticeable.
Laser hardening is used by several industries, including automotive and industrial equipment.
Ultrasonic machines have also been on the DMG Mori product portfolio for some time. But the machines began to adopt additive capabilities only about a year ago, again extending the scope of “hybrid.”
With ultrasonic grinding, a high-frequency oscillation is superimposed on the grinding wheel, which results in better surface finishes and longer tool life than conventional grinding or milling.
By incorporating the additive element into all of our subtractive processes, including milling, turning, surface hardening, conventional grinding and ultrasonic grinding, production can be easily consolidated in the same setup instead of requiring separate, and sometimes special, operations, Hyatt said.
Multitasking comes into play
Mazak recently began selling new hybrid machines that combine additive and subtractive technologies and allow for multiple operations at the same time.
The machine tool builder’s series of hybrid multitasking machines—Integrex, VC and Variaxis models—combine additive and subtractive technology, providing single-setup, complete-part machining or “done-in-one processing”—from raw materials to finished part.
Mazak believes hybrid multitasking machines will revolutionize manufacturing and play a critical role in smart factories.
The company in September introduced a multitasking machine called the VC-500 AM.
Multitasking machines are the key for manufacturers to survive in the future, said Joe Wilker, a product group manager at Mazak.
“Almost every manufacturer, job shop or industry out there has one or maybe more multitasking machines,” he said. “It is the only way to do business anymore.
“Instead of moving parts from a turning center to another turning center, a vertical machining center to a horizontal, we now just take all those processes and put them on one machine,” Wilker said.
The VC-500 AM features five-axis capability and additive technology to reduce time to market, cut R&D costs and recast product design.
It builds part features to near net shape up to 10 times faster than comparable systems—without wasting expensive material and losing time by subtracting large amounts of metal from a solid material using normal multitasking machining technology, according to Mazak.
The laser-cladding heads of the new Mazak VC-500 AM reside side-by-side with the subtractive machining spindle.
During operation, the VC-500 AM uses fiber laser heat to melt the chosen metal powder that will be used to the grow near-net-shape 3D forms. The cladding head applies the molten material layer by layer, all of which solidify as the desired part surface or features grows. The laser-cladding head can also be used to coat chosen sections of the part with metal, allowing the machine to repair worn or damaged high-value components.
The Variaxis i-600AM, another multitasking hybrid machine Mazak introduced last year, features an innovative Wire Arc-type metal-deposition system.
It helps shops quickly and easily grow part features then employ the machine’s five-axis, multisurface subtractive capabilities to produce high-precision parts complete in single setups, according to Mazak.
The Variaxis j-600AM’s wire arc-welding head is mounted on the machine’s headstock to deposit material layer by layer and grow near-net-shape 3D forms. The system deposits material faster because it uses wire instead of metal powder.
The machine is used for the production and repair of aerospace parts, molds and dies and oil-drilling components. It lets these parts retain their original durability and wear-resistant properties.
Mazak introduced the Integrex i-200S AM last year at an industry show in Tokyo.
It features a multi-laser deposition system. In multi-laser metal deposition, multiple laser beams in the AM head are used to melt powdered metal, which is fed through the center of the head. It is effective for the production of precise features, heat-sensitive, thin sheetmetal material and for complex surfaces.
In order to maximize the processing area, the AM head is mounted on a gantry and automatically moved to a storage area to prevent any contamination by machined chips or coolant during machining.
It is used for manufacturing applications like aerospace components, metal cladding for chemical plant valves and the repair of dies and turbine blades.
The machine’s multi-laser metal deposition head is what makes it unique, Wilker said.
Other heads have one laser beam coming down at the center and then argon gas coming in while the metal powder is blown into the laser beam. On the i-200S AM, there are multiple layers or multiple laser beams and a circular pattern focused to a point coming out of the nozzle, and the nozzle is inside the circular circumference of the laser beams, he explained.
‘Less work, faster results’
MC Machinery Systems, a manufacturer of metalworking and metal fabrication machines, is using additive and subtractive manufacturing together in some innovative ways.
MC Machinery unveiled the LUMEX Avance-60, which features hybrid 3D metal printing and CNC milling capabilities, at IMTS last year—following demand for a larger sister machine to the LUMEX Avance-25.
The LUMEX Avance-60 is 15 times bigger, said William Gillcrist, national product manager for the firm’s MC machinery systems machining and AM divisions.
“It is less hands in the pie, less effort, less work and faster results. Sometimes a process can take four to eight weeks when there are multiple steps involved. Now we can take that overall cycle and reduce it in one operation,” he said about the benefits of using additive and subtractive technologies together.
Hybrid machines are bound to become more popular in machine shops and factories around the US, Gillcrist said.
Several Japanese firms are using the machines, and Europe is beginning to adopt them more, he added.
As of January, there were no purchases or shipments on record for the LUMEX Avance-60.
“We are just demonstrating what it can do,” Gillcrist said. “It is going to be good at bigger parts that we couldn’t fit in the previous Avance-25.”
Matsuura, a machine builder, in conjunction with Panasonic, was the first to build a powder-bed-style hybrid system for AM that is mostly geared toward the injection molding industry.
The pair began building the first hybrid system in 2000.
Since then, the machine has seen many upgrades, the biggest being software. The upgrades include more control over toolpaths and laser settings.
“Matsuura’s additive machine is built like a machine tool, whereas most other additive machines are built more like printers,” Gillcrist said.
Laser upgrades and real time in-process monitoring and control will become more widespread throughout the AM industry, he added.
Legitimacy still questioned
While the integration of additive and subtractive manufacturing has proven to be effective, hybrid machines that incorporate both are not necessarily in high demand because a lot of people are still skeptical about them, Wilker said.
“There is a lot of hype about it in industry right now, and I think it is going to be the next generation … that is really going to take this to the next level,” he said.
“Right now, we are experimenting and playing with it. It takes time for people to understand that it is a legit process.”