How to 3D print with metal and which materials to choose

Why choose metal 3D printing? 

There are some considerable advantages for 3D printing with metal, when compared with traditional metal techniques or plastics 3D printing. These include: 

Greater design scope. Metal is well-suited to printing complex designs. This makes it a good choice for those wanting to create specialized and customized parts for a machine, for example 

Optimization. Parts printed with metal can be adapted to enhance their performance. 3D printing can produce lightweight parts, for instance, by reducing infill ratio, as well as through the design freedom the technology provides 

Good range. A wide variety of metals are available, offering businesses different physical properties 

Aesthetic finish. Metal doesn’t just perform well – it also looks good. This is an advantage for some certain use cases, such as making jewellery

Metal printing technologies 

If you want to enjoy the benefits of 3D printing with metal, you’ll need to use the right technology. Here is a run-through of the most well-known metal printing technologies: 

Direct Metal Laser Sintering (DMLS). DMLS uses a laser to melt and fuse the metal powder, forming a printed object layer-by-layer on a build-plate. It uses alloys (rather than a single type of metal), which are made up of metals with different melting points. The metals fuse as the temperature rises. 

Bound Metal Disposition (BMD). BMD works through extrusion, in much the same way as FFF printing. It requires metal bound in rods of polymer or sacrificial wax, rather than powder. This can then be melted and extruded through the printer's nozzle. 

Selective Laser Melting (SLM). Like DMLS, SLM also uses a laser and prints the object on a build plate. It only requires a single metal, however, as it prints at one temperature.  

Electron Beam Melting (EBM). As the name suggests, this printer uses an electron beam to melt the metal, rather than a laser. It’s less commonly used than SLM or DMLS. 

Ultrasonic Additive Manufacturing (UAM). UAM uses room-temperature metal deposition to create 3D printed metal objects. This technology isn’t widely used. 

Investment casting. Although it is not a 3D printing technique, investment casting uses a mold, into which the molten metal is poured. Investment casting allows for a good level of detail, making it appropriate for smaller printed parts. 

CNC machining. All of the technologies above are costly – with some being at a price point that’s too high for SMEs. While not a 3D printing technique, CNC machining is more affordable, enabling companies to create metal prototypes – though it does have a few limitations, one being that it is not so effective for parts that require geometric complexity.

Sylatech uses Ultimaker 3D printers to speed up its rapid prototyping process for metal production processes 

Types of metals

When 3D printing with metal, it’s important to consider its properties – and the advantages and disadvantages of each type.  

Aluminum alloys   

• Pros: Conducts electricity well, has good mechanical properties, low density 

• Cons: Isn’t very hard 

Cobalt-chrome superalloys 

• Pros: Resistant to wear and tear, corrosion-resistant, copes with high temperatures, hard 

Inconel (nickel alloys) 

• Pros: Good mechanical properties, heat-resistant, can cope with extreme environments 

Precious metals (silver, gold etc.) 

• Pros: Appearance, suitable for jewelry-making 

• Cons: Expensive, sometimes difficult to obtain 

Stainless steel 

• Pros: Resistant to wear and tear, hard, easy to weld 

Titanium alloys 

• Pros: Good strength-to-weight ratio, resistant to corrosion, doesn’t expand much when exposed to heat 

3D printing with metal can also take the form of metal filling. This means metal powder is poured into another material, which makes it heavier. It also gives the printed object a metallic finish.  

Common applications of metal

The following are a few ways in which metal 3D printing is used by various industries:  

Aerospace and aviation. Metal is a valuable material in aerospace and aviation. It can be used to 3D print structural components (often with a titanium alloy). Fuel nozzles can be easily created for specific airplanes, and jet engines can potentially be constructed out of 3D printed parts.  

Engineering. Metal printed parts are useful for a variety of engineering applications. They can also be used to replace or repair existing parts, which eradicates the need to wait for a third-party supplier to send a replacement.  

Medical. Medical applications for 3D printing with metal include prosthetics, replacement hips and knees, hearing aids, and shoe insoles. Dentists are also using metal 3D printing for fabrication purposes.  

Designers. Jewellery-makers and other designers use metal to create end-use consumer goods, or for features on shoes or clothing (e.g. buckles and fastenings).  

Hardware requirements 

When 3D printing with metal, certain hardware criteria must be met. These are: 

Having an appropriate build-plate / bed.  The temperature should be between 45°C and 60°C. There’s no need for an enclosure.

The right surface. The build surface may require painter’s tape, PEI, and a glue-stick. 

Appropriate extruder.  A specialized hardened steel nozzle is required, and the temperature should be between 190 °C and 220 °C. 

Cooling fan. A cooling fan is a necessity.

Choosing your filament 

When 3D printing with metal, it’s important to choose the right material for the job. The metals detailed above are suitable for a range of different applications. Alternatively, there are some instances in which an alternative material could be used. For example: 

• BASF Ultrafuse 316L. Available on the Ultimaker Marketplace, BASF Ultrafuse 316L is a metal-polymer composite. It is compatible with Ultimaker’s desktop 3D printers, and is suitable for making tools, fixtures, jigs, small-batch parts, and functional components

A part printed in BASF Ultrafuse 316L 

• DSM Arnitel ID 2060 HT and Clariant PA6/66GF 20 FR. Both filaments are thermoplastic and able to withstand very high temperatures, just like a metal. They also offer good wear resistance

• Arkema FluorX and DuPont Zytel 3D12G30FL BK309. These materials make excellent substitutes for stainless steel, as they offer a high level of corrosion resistance. Chemicals such as solvents, automotive fluids, and cleaning agents don’t result in any deterioration

• Igus Iglidur 180PF. This filament is self-lubricating, which makes it highly resistant to wear and tear. It’s suitable for creating parts that are traditionally metal, such as bearings, toothed wheels, piston rings, and gears

• XSTRAND GF30-PA6. This filament contains 30% glass fiber, which gives it good chemical resistance, high tensile strength, and a good operational temperature. It is well-suited for printing jigs and fixtures

A part printed in Owens Corning XSTRAND® GF30-PA6 

How to print with metal filaments

If you’re using SLM or DMLS technology, this is how 3D printing with metal works. 

Incorporating gas. Before any printing takes place, the build chamber needs to be filled with an inert gas. This reduces oxidation and enables the chamber to reach an optimum temperature for printing.  

Metal powder and scanning. Metal powder is applied to the build plate, then the laser scans the component’s cross-section. This fuses the metal particles together, thus creating the next layer.  

Subsequent layers. When the first layer is complete, another layer of metal powder is applied, and the process is repeated.  

Support structures are used to keep the parts attached to the build plate; these help to reduce warping, which may occur in high temperatures. After the printed object is cooled, the excess powder needs to be removed manually, and the object treated.  

With BMD technology, metal is melted within a special extruder, and is deposited on the build plate below, layer by layer. As with SLM and DMLS printing, the item will need to be treated and cleaned after printing.