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

The 3D additive manufacturing process using metal can produce visually and physically impressive results. Metal is ideal for creating custom pieces that are heat, chemical and impact resistant.

For some industries, metal offers significant advantages. Here’s more information on how to use metal in 3D printing and the best ways to unlock its potential.

Why choose metal additive manufacturing?

There are some considerable advantages to metal-based 3D printing over traditional metal techniques or plastic 3D printing. These include:

High design possibility. Metal is very suitable for printing complex patterns. Therefore, it is a good choice for those who want to create specialized and customized parts, for example, for a car.

Optimization. Metal stamped parts can be adapted to improve performance. 3D printing can produce lightweight parts, for example, by reducing the fill ratio, as well as the design freedom provided by the technology.

Good range. There are various types of metals available, which give companies different physical properties.

Aesthetic finish. The metal not only works well, it looks harmonious. This is an advantage for some use cases such as jewelry making.

Metal printing technologies

If you want to enjoy the benefits of 3D printing using metal, you will need to use the right technology. Here is an overview of the most popular metal printing technologies:

• • Direct metal laser sintering (DMLS). DMLS uses a laser to melt and mix metal powder, forming a printed object layer by layer on a build plate. It uses alloys (more suitable than a single type of metal), composed of metals with different melting points. Metals melt as the temperature increases.

• • Bonded metal deposition (BMD). BMD works by extrusion, just like FFF printing. Requires metal bonded in polymer rods or sacrificial wax rather than powder. This can then be melted and extruded through the printer nozzle.

• • Selective laser melting (SLM). Like DMLS, SLM also uses a laser and prints the object onto a build plate. However, it only requires one type of metal because it prints at a certain temperature.

• • Electron Beam Fusion (EBM). As the name suggests, this printer uses a beam of electrons to melt metal, rather than a laser. It is less used than SLM or DMLS.

• • Ultrasonic additive manufacturing (UAM). UAM uses room temperature metal deposition to create 3D printed metal objects. This technology is not widely used.

• • Investment casting. Although not a 3D printing technique, investment casting uses a mold into which molten metal is poured. Lost wax casting provides good detail, making it suitable for smaller parts.

• • CNC machining. All the above technologies are expensive: some are priced too high for SMEs. Although not a 3D printing technique, CNC machining is more accessible and allows companies to create metal prototypes, although it has some limitations, one of which is that it is not as efficient for parts that require geometric complexity.

Types of metals

When 3D printing with a metal, it is important to consider its properties and the pros and cons of each type.

Aluminum alloys

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

• • Cons: Not very difficult

Superalliage cobalt-chrome

• • Pros: wear-resistant, corrosion-resistant, high temperature, heavy.

Inconel (nickel alloys)

Precious metals (silver, gold, etc.)

• • Pros: Appearance suitable for jewelry making

• • Cons: Expensive, sometimes difficult to obtain

Stainless steel

Titanium alloys

• • Pros: good strength-to-weight ratio, corrosion-resistant, does not expand too much when exposed to hea

Metal-based additive manufacturing can also take the form of metal filling. This means that the metal powder is poured into another material, making it harder. It also gives the printed object a metallic finish.

Common metal applications

Additive manufacturing using metal is used by various industries:

• • Aerospace and aeronautics. Metal is a valuable material in the aerospace and aviation industry. It can be used to 3D print structural components (often with a titanium alloy). Fuel nozzles can easily be created for specific aircraft, and jet engines can be built from 3D printed parts.

• • Engineering. Metal stamped parts are useful for a variety of technical applications. They can also be used to replace or repair existing parts, eliminating the need to wait for a replacement to be sent by a third-party supplier.

• • Doctor. Medical applications for metal 3D printing include prosthetics, hip and knee replacements, hearing aids, and shoe insoles. Dentists also use metal 3D printing for manufacturing purposes.

• • To get dressed. Jewelry manufacturers and other designers use the metal to create final consumer goods or for useful features on footwear or clothing items (for example, buckles and fasteners).

Hardware requirements

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

• • Have a suitable construction plate/bed. The temperature should be between 45°C and 60°C. No need for a case.

• • The right surface. The build surface may require tape, PEI, and an adhesive.

• • Suitable extruder. A special nozzle made of hardened steel is required and the temperature must be between 190°C and 220°C.

• • The cooling fan is a must.

Choice of filament

When 3D printing with metal, it’s important to choose the right material for the job. The metals described above are suitable for a range of different applications. Alternatively, there are some cases where another type of material could be used. For example:

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

• • DSM Arnitel ID 2060 HT and Clariant PA6/66GF 20 FR. Both filaments are thermoplastic and able to withstand very high temperatures, like a metal. At the same time it offers good wear resistance.

• • Arkema FluorX and DuPont Zytel 3D12G30FL BK309. These materials are excellent substitutes for stainless steel because they offer a high level of corrosion resistance. Chemicals such as solvents, automotive fluids and cleaners do not cause any harm.

• • Igus Iglidur 180PF. This filament is self-lubricating, which makes it very resistant to wear and tear. It is suitable for the production of traditionally metallic parts, such as bearings, gears, piston rings.

• • XSTRAND GF30-PA6. This filament contains 30% glass fibers, which gives it good chemical resistance, high tensile strength and optimal operating temperature. It is very suitable for printing masks and lighting fixtures.

How to print with metal filaments

If you use SLM or DMLS technology, you should know that this is how metal-based 3D printing works too.

Gas

• • Before any printing, the build chamber must be filled with an inert gas. Its purpose is to reduce oxidation and allow the chamber to reach an optimal temperature for printing.

Metallic powder and scanning

• • Metal powder is applied to the build plate, then the laser scans the cross section of the component. This fuses the metal particles together, creating the next layer.

Subsequent layers

Support structures are used to keep parts attached to the build plate. It also helps reduce warping, which can occur at elevated temperatures. After the printed object has cooled, excess powder must be removed manually and the object must be treated.

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