3D Printing & CNC

3D printing and machining are often considered competitors, but they can also be effective partners. In fact, 3D printed parts are routinely machined to create higher tolerances and better surface finish. Meanwhile, parts that were once milled from a solid block of metal are often 3D printed far faster and in more complex shapes.

A growing number of hybrid manufacturing machines wrap 3D printing and CNC machinery into one package to better automate and accelerate part production.

Machine makers say hybrid technology overcomes the shortcomings of both of their parent technologies and enables manufacturers to produce more accurate and higher-quality components faster and at a lower cost. It is less wasteful than machining alone and more productive and precise than 3D printing alone, with no manual labor to move parts around an no programming two distinct pieces of equipment.

What are hybrid CNC-3D printing machines?

Hybrid manufacturing is a relatively new method that combines additive manufacturing and subtractive manufacturing technology in one machine. These machines use 3D printing to produce the basic, near-net shape of the part in metal or plastic. Then, another unit or tool head mills the part to the required tolerances. As a result, manufacturers (and their customers) have the complex geometries of additive manufacturing and the detailed surface quality of milled components.

In addition to building a part from scratch, these machines are ideal for adding features to existing parts, carrying out repairs of parts, and applying coatings to parts before the machining post process.

Hybrid manufacturing machine operations differ between manufacturers, but they generally fall into two categories:

• Sequential hybrid manufacturing machines complete the full AM sequence first, producing a 3D printed near-net shape part before moving on to the subtractive process.

• Alternating hybrid manufacturing machines, on the other hand, swap between AM and milling units throughout the manufacturing process. Some alternating machines can even machine one part of the component while the AM unit prints another section.

Technically, almost any 3D printing technology could be combined with a CNC machine and there are a few upgrade kits to convert your existing machining units. However, the technology is still developing and the current options are limited to a few combinations. These include:

• DED/CNC: Directed energy deposition (DED) is a metal AM technology where the material — wire or powder — is fed through a narrow nozzle and melted into shape with an electric arc, laser, or electron beam. The advantage of DED is the ability to feed the material from any angle, allowing for 5-axis deposition. This is also used for metal part repair.

• LPBF/CNC: In laser powder bed fusion (LPBF), the machine lays down a thin layer of metal powder, melts the layer’s shape with lasers, and repeats the process until the part is complete. LPBF can, in theory, produce parts without support structures due to the surrounding unfused powder providing the necessary support.

• FDM/CNC: Unlike the previous two methods, fused deposition modeling (FDM) printers melt and extrude metal or thermoplastic filaments or pellets in layers to create the desired geometry. This technology can be much cheaper while still having good strength characteristics (particularly with reinforced polymer filaments), but the parts can require support structures during printing.

All-In-One Hybrid Software

Ideally, a hybrid manufacturing machine should work with a single round of programming, and most manufacturers aim for simple operability. Some companies produce their own CAD/CAM solutions, although many rely on operating software developed by third parties.

For example, Meltio offers Meltio Space, a state-of-the-art toolpath generator software for the Meltio Engine Robot Integration with an easy-to-use interface for planar, non-planar, and variable extrusion toolpaths for the ABB, Kuka, Fanuc, and Yaskawa robots.

Hybrid manufacturing is a working solution for producing both prototypes and functional end-use parts, in addition to repairing existing components. Hybrid manufacturing is particularly attractive to smaller companies that require both AM and machining capability.

These machines can allow them to produce both kinds (or hybrid) parts without investing in two machines. It can also resolve (and has resolved) issues related to part complexity and productivity in demanding, large-scale industries, such as automotive and aerospace.

Pros & Cons of Hybrid Manufacturing

Hybrid manufacturing offers many benefits over pure AM or subtractive methods. One of its most significant advantages is the ability to increase productivity. As both the AM and machining processes can be run in a single machine, there’s no need to swap parts and recalibrate equipment. The machining unit can also partially or completely replace manual AM post-processing, which also speeds up production.

Another important fact is that hybrid manufacturing can achieve higher precision and tighter tolerances than most 3D printers alone. AM creates more complex geometries and part structures than machining can produce, such as part consolidation, internal channels, and lattice-filled walls. Producing the entire part in one machine also reduces the chance of processing flaws or errors. As a result, hybrid parts can perform better and have higher quality.

Hybrid machines enable you to use multiple materials in a single part, opening the door to significant mechanical performance improvements and cost savings. You can clad weaker parts in stronger metals, add high-performance materials to improve part movement or heat transfer, or save on material costs by using expensive materials only where they’re needed.

Another remarkable advantage is that hybrid manufacturing eliminates much of the waste that is inherent to subtractive technologies, reducing material consumption by up to 97%, one recent study found. 3D printing the part to a near-net shape means less material ends up as shavings on the factory floor. With DED/CNC machines, it’s also possible to add material only to select locations.

This allows users to repair broken components and speed up production by adding metal to parts such as components used in the marine and oil & gas industries. Conversely, the CNC unit can machine fine internal structures between material deposition runs.

Last but not least, hybrid can cut up-front investment and running costs. Instead of purchasing both a CNC machine and an industrial 3D printer, it may be cheaper to buy a hybrid machine. A single hybrid machine also consumes less energy and requires less floor space than separate AM and CNC units.

Despite its great advantages, hybrid isn’t a perfect solution for every manufacturing need. Although these machines can lower initial investment, they are not cheap and may be outside the budgets of smaller companies. Operating hybrid machines can be complicated and requires the operator to have an intricate understanding of both 3D printing and CNC machining to determine the best way to manufacture a given part.

Applications of Hybrid Manufacturing Machines

Hybrid manufacturing is suitable for a great number of industries. Any application that relies on precisely manufactured parts from metals or thermoplastic stands to benefit from hybrid manufacturing technologies. However, some of the sectors that are particularly suitable are these:

Aerospace: The aerospace industry requires heat-resistant, strong, and lightweight parts with tight tolerances. Hybrid manufacturing can manufacture these components from reinforced thermoplastics and metals like aluminum.

Automotive: Vehicle engines and chassis contain huge numbers of complex parts. Hybrid manufacturing gives automotive manufacturers to produce these components in a single machine, lowering material and labor costs.

General Engineering: Maximum uptime is vital for any manufacturing industry. With hybrid manufacturing solutions, it’s possible to repair broken machinery components, which lowers costs and requires less standing inventory.

Medical: Hybrid manufacturing can help medical professionals create perfectly fitting customized implants, prosthetics, and surgical tools. The AM component allows for part customization, while CNC machining ensures an ideal part quality.

Meltio Engine Hybrid Solution

Spanish metal 3D printer maker, Meltio, offers a CNC integration unit called the Meltio Engine that can turn almost any industrial CNC machine or robotic platform into a hybrid metal manufacturing system with no inherent size constraints. By retrofitting your existing CNC machine, you’ll have a new capability to conduct cost-effective component creation, repair, part augmentation, and feature addition on metal parts, the company says.

The Meltio system is a Directed Energy Deposition (DED) process that precisely stacks weld beads on top of one another in wire form when introduced into the laser-generated melt pool. Meltio’s technology comes packaged in a compact deposition head with six low-power lasers that are capable of processing metal welding wire fed coaxially. The head is mounted next to the CNC milling machine spindle mount.