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What is 3D printing or Additive Manufacturing

2014-08-25 | Publicshed In: 3D Printing
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What is 3D Printing ?

 

3D printing is a process of making 3 dimensional physical objects from digital files. Unlike normal printing where prints are made on a paper, 3D printing makes real objects that you can touch and feel. This is achieved through a process of adding several two dimensional layers, one upon other, to form 3 dimensional objects called Additive Manufacturing.

This is different to traditional machining techniques (subtractive processes) where in unwanted parts of a material are removed by drilling, cutting etc. to retain the required object. Contrary to this, in additive manufacturing layers of metal are placed one over other to form the required shape. Currently 3D printing can produce objects in a variety of materials including plastic, metal, ceramic, synthetics and glass. Development is under way for making real life objects using concrete and other composites.

A brief time lime of 3D printing

The idea of 3D printing has been floating around for the past 20 years, however the first practical 3D printing machine is produced in early 2000.

 Advantages:

3D printing has many advantages over traditional manufacturing.  As, only the required materials are used to create an object, there is very little waste in creating physical objects.  3D printing is very useful and economical for low volume manufacturing like aviation or scientific industries as the shape/design of the object can be changed in its digital format for every second production unit.   This also paves a path for custom made objects eg. Signature table curios.  Also 3D printing is a successful tool for rapid prototyping.  When a design is made, it can quickly be turned into a real object.  Another significant area where 3D printing can be used is called as Bio Printing or human parts like teeth, hearing aids, bones etc.

Technologies:

There are several 3D printing technologies that are currently available and are further developed.  These differ mainly in the way layers are built to create parts. Some melt or soften material to produce layers (SLS, FDM), while others lay liquid materials cured by lasers. Lamination systems cut thin layers to shape and join them together. Each of them achieves the result in different ways and serves different purposes.  Below is a list of technologies that are available today:

 

Additive technologies

Base materials

Selective laser sintering (SLS)

Thermoplastics, metals powders, ceramic powders

Direct metal laser sintering (DMLS)

Almost any alloy metal

Fused deposition moulding(FDM)

Thermoplastics, eutectic metals

Stereo lithography (SLA)

photopolymer

Laminated object manufacturing (LOM)

Paper, foil, plastic film

Electron beam melting (EBM)

Titanium alloys

Powder bed and inkjet head 3d printing Plaster-based 3D printing (PP)

Plaster, Coloured Plaster

 

Printer family:

Just like normal printer family 3D printers are currently available in the market can be grouped into two categories Commercial and Personal.  While commercial printers are more expensive and have wide range of applications, personal printers are small and used for hobby purposes.

 

Applications:

3D printing can be used in many areas.  Below is a range of industries where 3D printing is currently used:

 

Additive Manufacturing:

In explaining the terminology of the new world of 3D printing, we said that Additive manufacturing can be treated as the root word of this technology.  By definition it is a process of adding materials to derive the desired structure. This is opposite to the traditional milling, carving and engraving techniques that are considered as deletion processes - 'simply removing the unwanted areas of a material to retain the wanted'.  Best examples that fall under this category are wood and stone carving, milled mechanical objects.


The next question to answer here is, how this differs to casting or forging.  Casting can come close to additive manufacturing as only required material is added into a mould.  However, this process involves making an object that is predefined by specific shape of its mould. Forging is also a type of deletion process wherein the force of forge will consolidate the required material and splits out unwanted.

Additive manufacturing involves adding thin layers of material one upon the other, either by melting them or gluing them.  This incremental micron by micron building character, combined with potential freedom of changing the composition of each layer, either in its shape or material characteristics, brings in a new world of possibilities. The ability to manipulate the precise composition of an object to a micron increases the ability to produce complicated shapes and forms.  This opens up a whole new world of making complicated forms and shapes that are not possible or complex to make in traditional methods.  

 

 

For example one such capability is making parts that contain multiple components together, rather than making them separately and joining them.  To demonstrate this let us take a simple example of a ‘bearing’. In traditional methods four components (i.e. inner shell, outer shell, roller balls and lock rivets) are made separately and assembled together. However, in additive manufacturing millions of micron sized two dimensional layers are stacked and glued together to replicate cross-sections of the bearing and the entire bearing comes out in one piece without any requirement of assembling multiple parts. 

Another embedded power is 'the ability of adding only the required materials'.  This helps the environment by reducing the loss of materials that occur in traditional manufacturing processes like crafting, milling, forging or moulding.  Simply stated you add what you want, weather it is the type of material, quantity or shape.

 

A combination of the above two capabilities can lead to manufacturing embedded components forming functional objects at one go. Taking this a step further, the possibility of assembly free manufacturing of structures or mechanisms that are completely enclosed is within the realm of possibility.  A good example could be manufacturing a car engine layer after layer without any requirement of joining multiple parts.  The advantages of this capability are massive.

 

For example consider a simple thing like a hair brush. It has got three parts made of three different materials (soft material for grip, hard plastic for the structure and semi-flexible/semi-rigid bristles).   While all of them are added to form the shape, the way we get there is different in traditional manufacturing compared to additive manufacturing.​ In the former the three parts are added together when they are formed in their entirety. In other words, three parts are made and then added together either by inserting one into the other or through gluing them together.  In the additive manufacturing this is made as one piece, by layering tiny slices of the object one upon the other consisting three different types of plastics.