Wire and Powder Additive Manufacturing Combined in One Machine
Isaac Maw posted on January 23, 2020 |
Meltio’s laser metal deposition technology can 3D print with robot-mounted modules.

Meltio has sponsored this post.

As adoption of additive manufacturing accelerates in 2020, users continue to seek out the best machines, vendors and technologies to meet specific needs and to best fit specific applications. For example, companies in the dental alignment and custom eyewear industries have identified polyamide SLS technology as a good fit, thanks to the relatively high accuracy possible in that process as well as the capability to nest a run of parts in three dimensions in the build chamber. But those parts are small, and in many industries larger, metal parts are the ultimate goal.

On the metals side, there’s a distinction emerging between systems that fuse powder—ideal for small, intricate parts with fine, complex features—and systems that fuse wire, which typically have high deposition rates but low-quality surface finish. Both have advantages and disadvantages, but many users need the benefits of each in a single build.

(Image courtesy of Meltio.)
(Image courtesy of Meltio.)

How Does Meltio’s LMD Metal AM Process Work?

Meltio, a 3D printing technology company based in Linares, Spain, has developed a unique multi-laser printing head which is available as a tool mounted on a robot arm or CNC machine. Similar print head modules can be found in the company’s additive manufacturing machines, such as the M450.

In laser metal deposition (LMD) additive manufacturing processes, lasers are directed to create a meltpool on the surface of the workpiece. Material, in powder or wire stock, is fed into the meltpool to build up solid metal with low porosity and a relatively high deposition rate compared to other metal additive processes, such as selective laser sintering (SLS).

While most LMD systems work with either powder or wire, the Meltio print head is capable of feeding both material types. According to the company, this allows users to take advantage of the high deposition rate and low porosity of wire feed systems, and also take advantage of the benefits of powder, such as the capability to mix powders and manipulate the metallurgy of the part during printing to obtain material combinations that are very difficult to build any other way.

How Does Meltio Compare to Other Metal AM Technology Options?

Speed is a major advantage of the technology and the company claims its LMD process is up to ten times faster than direct competitors.

Compared to other metal AM systems, Meltio’s dual material solution is compact. The print head measures 150mm by 265mm. Metal deposition can be performed in an argon gas chamber, such as in the Meltio M450 printer, or it can be done with argon gas shielding, similar to well-known GMAW processes. When used in the M450, a build volume of 150x200x450mm is possible in a machine footprint of 550x600x1400mm.

For advanced users, however, the greatest flexibility will be realized with the print head mounted on a gantry, robot or CNC milling machine. The company states that the print head and associated engine can also be used for cutting, polishing, welding, laser cladding and other laser-based processes besides AM.

(Image courtesy of Meltio.)
(Image courtesy of Meltio.)

What Should Manufacturers Consider Before Investing in Metal AM Equipment?

Additive manufacturing, especially for metals, is rapidly finding novel uses in the industrial space. Before investing in metal AM equipment, however, manufacturers should consider several factors. Below are a few important considerations.

How Should Parts be Manufactured?

Additive manufacturing processes have unique properties compared to conventional techniques such as fabrication, machining or casting. For example, because additive processes are digital and require no tooling, part complexity does not increase production cost per part, and there is no economy of scale when it comes to producing large runs of identical parts—with an additive process, it costs the same to print a thousand unique parts as it does to print a thousand identical parts.

To turn these unique properties into advantages, the part must be a good fit for the process. For example, a simple stamped sheet bracket made by the thousands with a press would not be a good fit for additive. Dental or medical devices, replacement parts and aerospace prototypes are ideal applications due to their low volumes and high cost to manufacture subtractively.

To optimize your process for additive, it’s ideal to redesign parts to better take advantage of the strengths of AM, free from traditional design constraints. Hollow, enclosed structures can save weight at no cost in strength, for example.

What’s the Best AM Process for an Application?

The second factor manufacturers will consider before investing in AM is the specific process that will be used. For example, within metal additive manufacturing, there are technologies on the market which use lasers to fuse layers of metal from a bed of powder, laminate sheets of material or deposit melted material onto the workpiece. Other systems may build a “green” part with powder and non-metal binder, which is then sintered in an oven, removing the binder and shrinking and solidifying the part.

Each of these different technologies has different advantages and disadvantages. For example, metal powder handling can be costly and inconvenient. While wire material is easy to use and has a high deposition rate, parts produced via wire deposition processes may require post machining to achieve close tolerances, such as on mating surfaces or holes.

A recent report from AMPower compared the build rate of a variety of metal AM technologies on the market. The report found that in general, wire deposition is capable of much higher max build rates, up to 1200 cc/hr. In comparison, the maximum build rate for a powder process was 800 cc/hr.

Meltio’s flexible LMD process, which uses multiple lasers to add energy to feed material and deposit it on the part, could be a favorable option for some users because of the capability to use both wire and powder material. This affords users more flexibility to provide a better AM solution for a wide range of parts and projects. This benefit is compounded by the cutting, welding, and finishing functions of the print head.

What Will an AM Solution Cost?

According to the AMPower report, the cost of a metal additive manufacturing machine scales to size, with large powder bed fusion (PBF), binder jetting (BJT), and directed energy deposition (DED) machines being the most expensive, and most DED systems costing the most. Metal fused filament processes, which typically require parts to be sintered in an oven after printing, are the least expensive.

Is Meltio LMD AM the Best Option?

Not every metal part is the best fit for additive manufacturing, and even among those that are ideal for additive, not every additive process is best for every part. Selecting the best additive manufacturing technology and equipment for your needs will greatly increase the success of adoption of additive manufacturing capabilities.

To learn more about Meltio, visit the website here.

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