3D Printing

How Does Metal 3D Printing Work?

How Does Metal 3D Printing Work?
Written by Shikha Mehta

Have you been under the impression that 3D printing is restricted to making prototypes out of plastic? If so, then let’s give you some new insights into this field. From tools made of stainless steel to jewellery made of gold, you can make anything using metal 3D printing. And this is not a combination of metal and plastic – it is pure metal.

3D printing has several techniques and technologies. This is the reason why you can use several types of raw materials to create objects with a 3D printer. These include plastics, metals and fusion of 2 or more materials. Let’s take a look at how 3D printing with metals is different from that of plastics.

What Is 3D Metal Printing?

When you work with metals, you usually use them in powder form. This could be either pure metal or in most cases an alloy like stainless steel or Inconel 625.

The machine creates the object layer by layer, solidifying and hardening the powder each time. The final product that you’ll get will be of the same hardness that the metal had before you crushed it into powder. In other words, it might be difficult for you to even say that the object is made with 3D printing technology!

Mostly, you use 3D printers for metallic objects when you want to create complicated models or personalized items. That is because a 3D printer works with a lot of precision. When you connect it to the computer, it understands the shape of the object as per its coordinates.

How does it Work?

There are several technologies of 3D printing that are useful when you want to use metal as your printing material. Every 3D printer is designed to insert a different type of raw material in it.

So, the one that you use for printing plastic objects will be very different from metallic ones. This is because plastic is used in resin or filament form, for which you need a different kind of chamber, extruder and temperature.

Here’s the basic way any metal 3D printer works:

  • You need to first create the object in a 3D CAD software.
  • Now, you connect the computer to the 3D printer.
  • As the printer takes instructions from the computer, the laser beam create the object in 2D form first.
  • It will extrude the powder on the surface in the same shape and then solidify and harden the powder completely.
  • Like this, layer by layer, it will continue till it completes the object.

The above process may vary more according to the type of printer you use. For metal 3D printing, following are the technologies that are most common in use:

DMLS 3D Printing

Direct Metal Laser Sintering is one of the most common technologies used for metals. The term sintering refers to converting powder into a solid surface without melting it. It is best for printing objects with alloys like steel, stainless steel or Inconel 625. Here’s how it works:

  • You put the powder in a chamber that has an inert gas to reduce oxidation and heat to the print temperature.
  • The printer will slice the 3D object in the file into 2D layers.
  • It extrudes the powder on the surface in the shape of the slice.
  • The laser beam will heat the powder and weld it together. This solidifies the layer.
  • It repeats the above process layer by layer till the object is complete.

Applications:

  • Medical prosthetics with titanium alloys
  • Dentistry crowns, bridges and prosthetics with cobalt-chrome alloys
  • Aircraft turbine parts with lightweight alloys and aluminium
  • Fine jewellery made of aluminium or gold
  • Detailed prototypes made of titanium

SLM 3D Printing

Very similar to DMLS, Selective Laser Melting also uses laser beam to fuse powdered metal into an object. The difference lies in the temperature at which it works and the elements it deals with. While DMLS is more suitable for alloys, SLM is more suitable for pure metals. This is because it melts the powder before solidifying and hardening the surface. So, you may say that the working is the same as DMLS, but it uses more power and works at a higher temperature.

Applications:

  • Jewellery made of pure metals like platinum, palladium and silver
  • Airplane and automotive parts made of titanium
  • Machinery, building material and motors made of copper
  • Orthopaedic and dental implants made of titanium or stainless steel

SLS 3D Printing

Selective Laser Sintering is considered to be a common technology used in stainless steel and copper 3D printing. It is very similar to DMLS, where you use a CO2 laser for sintering. As the laser sinters a layer of the powder, the build platform goes down and the next layer is made the same way.

Applications:

  • Medical and dental implants made of stainless steel
  • Automotive and electronic hardware
  • Aerospace and military
  • Wind tunnel models

EBM 3D Printing

Electronic beam melting uses electromagnetic coils for printing objects. It is mostly used for printing thicker objects made of titanium or cobalt-chromium alloys. The technology is also great for an aluminium 3D printer. Since the beam is made of electrons, the material you’re using needs to be conductive. Here’s how it works:

  • You need to place the printer in a way that the printing area is in a vacuum.
  • Insert the metal powder in the feeder and start the printer.
  • Upon doing so, the internal pressure will reduce and create a vacuum, which heats the build platform.
  • When the bed reaches the required temperature, the powder falls on it and the electron beam solidifies it.
  • The above process repeats layer by layer, till your object is ready.
  • You need to remove the remaining powder covering the object to give the final finishing.

Applications:

  • Medical implants made of titanium-based alloys
  • Turbine blades and engine parts made of aluminium or other conductive alloys
  • Designing lightweight components for aerospace industry

RPD 3D Printing

Rapid Plasma Deposition is a special technology used in a titanium 3D printer. It is different from the above processes of 3D metal printing. Instead of using metal powder, it uses a titanium wire as input material. The process can also be used for tool steel, tungsten, aluminium, Inconel, copper, and stainless steel 3D printer. Here’s how it works:

  • You insert a 3-4 mm long titanium wire that is 8-12 mm thick inside the chamber.
  • This chamber has inert argon gas where the wire starts melting as the laser beam heats it.
  • The liquid builds up on the printing bed in layers, as per the shape of the object.
  • It solidifies soon to provide a strong and durable object with a rough surface.

Applications:

  • Repairing and functional parts
  • Structural parts of commercial aircraft using titanium or titanium-based alloys

Lost Wax Casting

This method is commonly applicable for a gold 3D printer. This is because it does not use metal powder unlike most of the above methods. There are 2 reasons why this makes it suitable for printing gold:

  1. Gold powder can be harmful if inhaled
  2. And it is super-expensive.

Apart from gold, the method is also used for making copper objects. Here’s how it works:

You create the object you want with wax using SLA 3D printing (a technology more common with resin 3D printing).

  • Heat the plaster mould to the extent that the wax melts away completely from the inside.
  • Now, in the empty mould, you pour the melted metal.
  • Once it cools and solidifies, your model is ready which you can polish later for a better finishing.

Applications:

  • Jewellery and accessories made of gold, silver, bronze or brass
  • Engine blocks made of copper
  • Dental restorations made of aluminium
  • Sculptures made of brass or bronze

Binder Jetting

This is yet another technology used in a powder 3D printer, which uses another kind of binding agent. Hence, it works a little differently:

  • A thin layer of powder is spread across the printing bed in the shape of the object.
  • A printer head travels over the bed, dispersing the binding agent on the powder.
  • This binding agent is a liquid, which fuses the powder and converts it into a solid surface immediately.
  • The platform goes down and the next layer is made in the same way, till the object is complete.
  • Then, the object is heated again to remove the binding agent and metals with low melting points fill up its gap.

Applications:

  • Moulds and prototypes
  • Aerospace parts
  • Jewellery
  • Colourful decorative items

How is Metal Filament Different from 3D Metal Printing?

In metal 3D printing, we generally use pure metals or alloys in powder, wire or liquid form. So, the object that you print will be completely metallic. On the other hand, a metal filament is made by fusing metal powder in plastic. The percentage of the two components may vary.

Most of the time, metals like copper, bronze, stainless steel or brass are fused with PLA plastic for making a metal filament. These materials provide a metallic finish but will be comparatively brittle in nature. They’re heavier and costlier than the usual plastic filaments but cheaper and lighter than pure metal.

Applications:

  • Sculptures
  • Accessories and fashion jewellery
  • Artefacts for museums

Top 3 3D Metal Printers

Given that the material you use is pretty expensive, a metal 3D printer will cost you a good deal. It’s not something you can use at home – they’re only fit for manufacturers. You could possibly figure it out from the uses of the printer too.

Let’s take a look at some of the best 3D metal printers in the market:

Markforged Metal X

This is an easy-to-use 3D printer that provides you with a wide scope of printing materials and objects. These include stainless steel, copper, Inconel 625, titanium, aluminium and tool steel. If you compare with DMLS printers, the price of Markforged Metal X is pretty reasonable, given how easy and convenient it is to use.

Technology: Atomic Diffusion Additive Manufacturing (a technology similar to FDM)

Applications:

  • Aerospace manufacturing
  • Functional prototypes of surgical instruments
  • Hose fittings and accessories
  • Gripper jaws

Desktop Metal 3D Printer – Studio System 2

This is one of the most budget-friendly metal 3D printers you can find in the market. Its working is similar to an FDM printer, but the technology holds metal powder within a polymer. When you start the printer, it will extrude the metal powder and sinter it to create the object.

Technology: Bound Metal Deposition

Applications:

  • Manufacturing parts and components
  • Moulds
  • Aerospace and machinery parts
  • Jewellery

Desktop Metal Production Printer

Using binder jetting technology, this printer is useful for a metal 3D printing service provider as it supports plenty of materials. These include various variants of steel, aluminium, bronze, tungsten, titanium, cobalt, chrome, nickel and many other alloys. Surely, the price of this metal 3D printer is higher than the rest, but worth it.

Technology: Single Pass Jetting

Applications:

  • Machinery parts
  • Surgical tools
  • Automotive parts
  • Watch cases

How to Choose the Best Technology for Metal 3D Printing?

More than the technology, you need to look into the 3D printer you’ll be using. It totally depends on the metals or alloys you use as raw materials and the final product that you’re manufacturing. The technology you choose needs to be easy, convenient and cost-effective, producing the best quality in the end.

Are you looking for intricate designs or simple ones? Are you working with precious metals or alloys? All of these factors matter in understanding what kind of metal 3D printing technology will be most suitable for you.

About the author

Shikha Mehta

I discovered my talent in writing while I was in high school. Since then, I discovered the joy of sharing your knowledge with people around you. This is the reason why I love making my contributions to Insights of Technology. Being a certified content writer, I have been writing on several topics, science & technology being one of my favorites.

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