Metal 3D Printing Technologies: Guide to Metal 3D Printing

Among additive manufacturing techniques, metal 3D printing is changing the game most particularly. It’s already making its marks in fields such as aeronautic which need innovative ways to create high-performing mechanical parts. 3D printing brings exceptional benefits to prototyping and production, which will bring a competitive advantage to your business, if used properly:

  • Complex designs, and shapes that would be impossible without layer-by-layer production
  • Speed, and reduced assembly time
  • Topology optimization and weight reduction
  • Cost-efficiency for short runs
  • Mass customization
  • Remote production when using an online 3D printing service.

With this guide, we hope to help you navigate the Metal 3D printing technologies.

Whereas metal 3D printing requires at least 6 steps:

  • CAD Design
  • File Preparing and Upload
  • Printing
  • Heat Treatment
  • Post-Processing
  • Metrology

There are two big families of metal AM:

DIREKT METHODS

Direct methods which consist in directly creating the object in metal. Parts thus created can be used for technical and engineering uses:

  • Powder Melting Technologies: Laser melting and Electron Beam Melting
  • Laser Metal Deposition
  • Binder Jetting

HYBRID METHODS

Direct methods that combine 3D printing with another technology to create metal objects. These parts will be less strong, and used mostly for aesthetics uses like jewelry:

  • Wax Casting
  • Sheet Lamination

 

 

  1. DIREKT METHODS

 

Powder Bed Technologies

Laser Metal Deposition

Binder Jetting

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High Density Precise Very Fast

Relatively Slow Finishes Required Mechanical Limitations

Applications

Prototyping Production

Repair Tools

Prototyping Arhitecture

Materials Titanium

Stainless Steel

Aluminum

Cobalt’s alloys

Raw Steel

Stainless Steel

Aluminum

Stainless Steel infiltrated with Bronze

 

  1. A Powder Bed Technologies

 

  • Laser Melting (known as DMLS, SLM or DLP)

How it works

In laser melting, a high-temperature Ytterbium laser melts locally the metal powder, to create the object layer by layer according to the CAD file.

 Materials

Titanium, Stainless Steel, Aluminum.

Good to know

The parts endure a high thermic stress during production. To reduce this stress, and attain higher mechanical properties, a heat treatment is often applied after production.

Applications

Prototyping and production.

With a density up to 99.5%, parts produced with laser melting are highly resistant, and ideal for mechanical parts such as propellers, gears, etc. in industries such as automotive, aerospace, electronics.

  • Electron Beam Melting (EBM)

How it works

The powder is heated locally by one or more electron beams, to create the object layer by layer according to the CAD file. The process has to be done under a high vaccum environment to prevent oxidation of the material.

Materials

Titanium and Cobalt’s alloys.

Good to know

EBM is faster than laser melting technologies but a bit less accurate than the laser based techniques because of the width of beam. The temperature during the process is evenly distributed which provides good strength properties.

Applications

The size of the object is limited by the size of the machine which is relatively small but can produce very fast parts for many industries. Engineering, aerospace or high tech products are already using it for prototypes, mechanical parts or specifit tools.

Finishes (for Melting and EBM)

Basics: Support removal and surface sanding to smooth the roughness.

Possible additional finishes: processing, polishing, grinding, drilling, threading

  1. A  Laser Metal Deposition
  • Laser Metal Deposition (LMD or DED)

How it works

Laser Metal Deposition (LMD) can be compared to the plastic Fused Deposition Modeling (FDM) as the feedstock is brought and fused at the same time through a nozzle. The feedstock can be either powder or wires and the heat source can be a laser, an arc or an e-beam. The substrate can be positioned either in a stationary position (3−axis systems) or on a rotating stage (5+ axis systems) to increase the ability of the machine to process more complex geometries. At the end of the process, the object is detached from the platform.

Materials

Mainly steel (raw and stainless) and aluminum.

Applications

LMD is mainly used for repairing works on engines and large-sized objects. It is indeed very easy to add material to existing object and to achieve precise work with this technique. It is also used in medicine or engineering for complex and custom tools.

Finishes

To provide a good surface aspect, speed has to be relatively low in order to perform a good melting and welding process with the layer below. The parts can be heat-treated to reduce residual stress and to improve mechanical properties. It is also often recommended to sand the parts to eliminate any layer mark.

Then, the objects can be processed, polished, grinded, drilled, threaded…

  1. A Metal Binder Jetting
  • Binder Jetting

How it works

In Binder Jetting, an inkjet head deposits a liquid binding agent on the powder according to the CAD File layer by layer. Multiples heads can be used to speed up the process. At the end, the object is extracted from the unbound powder, cleaned and prepared for consolidation.

Consolidation

This process is essential with the metal binder jetting technology to add the complete mechanical properties of the material and to avoid porosity. This step is achieved in a hot isostatic pressing. The device will cure the object uniformly with heat and pressure. During the heating, the binding agent melts to let the powder form a homogeneous structure.

Materials

Stainless Steel with infiltrated bronze.

Applications

As the technology allows very large, fast and cheap 3D printing, it is possible to print large sized prototypes, architectural structure but also gears and complex prototype parts.

Finishes

The objects can be processed, polished, grinded, drilled, threaded…

Good to know: Infiltration

Often, Binder Jetting uses a method called infiltration. With a lower melting temperature alloy, we infiltrate the 3D printed structure to make the material denser. The infiltration is made with molten bronze to make the material 60% stronger.

 

  1. HYBRID METHODS

 

 

Wax Casting

Ultrasonic Additive Manufacturing

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Very Precise

Very Fast and Cheap

Several Steps Required Not for Complex Shapes

Applications

Jewelry Ornaments

Prototyping Proof of Concept

Materials Brass

Sterling Silver

Zinc

Gold

Aluminum

Brass

Copper

Stainless Steel

 

  1. B Wax Casting
  • Wax Casting

How it works

The principle is to 3D print a very precise wax model of your 3D design. Then, it is covered with plaster and covering materials to create a mold. The metal is melted to liquid state and poured into the mold. The heat and molten metal dissolves the wax and fills the mold. When it has cooled down, the mold is carefully opened or broken to extract the part for finishes.

Materials

Brass, Sterling Silver, Gold or Zinc

Applications

Jewelry and ornamental parts. It can’t be used for technical parts.

Finishes

Finishes of wax casted object consists in multiple polishing process to obtain a smooth and shiny surface. The object can then be crimped with gemstones of your choice.

  1. B Ultrasonic Sheet Lamination
  • Ultrasonic Sheet Lamination (Known as UAM)

How it works

On a side, a roller filled with metal foils displays the material on a cutting bed. A laser cuts the layer according to the 3D file and then, an ultrasonic consolidation welds the sheets together. At the end, the cut excess material is removed to obtain the 3D printed object.

 Materials

Multiple materials like Aluminum, brass, copper, stainless steel or steel.

Applications

Can be used for rapid prototyping and POC objects. Allows multimaterials, is cheap and fast.

Good to know

Excess material is not reusable but even though it makes the process very low cost. For complex shapes, CNC machine are often used to achieve these cuts.

 What is Ultrasonic Consolidation

The principle is based on a low temperature process. The material foil is placed on an anvil and fixed on place. A sonotrode (device that create the ultrasonic) passes above the foils and applies pressure and ultrasonic oscillations to it. The process welds the sheets together.

Finishes

The sheets must be verified in order to be sure that the welding has been properly done. Then, the side of the objects must be sanded to remove the layer marks. Polishing can be done to give a very smooth aspect to the parts.

 

 

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