Three-dimensional (3D) printing, a
form of additive manufacturing, has caused quite a stir in the industrial
manufacturing sector. Although the technology is still developing, researchers
at MIT have already come up with the concept of four-dimensional
(4D) printing. Could this be the next big thing in manufacturing?
3D printing technology
The incredible 3D printing
technology was developed by Charles W Hull in 1983
and has since seen rapid wide-ranging applications. In this type of printing,
the hardware is made to deposit material, layer upon layer, in precise
geometric forms to create an object using 3D object scanners or data
computer-aided-design (CAD) software. It is unlike conventional manufacturing
or subtractive manufacturing, where the material is removed by using milling,
machining, carving, shaping, etc. to create an object.
The advantages of 3D printing are
for all to see. From small components to aerospace equipment, its applications
are ever expanding in various fields. From a simple production process, it now
supports convergence technologies, used in food packaging, jewelry and
equipment, and high-tech sectors covering aerospace, architecture, automotive
industry, education, medicine, military, etc.
4D printing technology
Like 3D printing, 4D printing is
also based on Stereolithography
(SLA), which builds 3D objects, layer upon layer, using smart
materials, such as photo-polymeric liquid. In the 4D printing process, a smart
3D object is created from smart materials that can change their shape over
time, if exposed to water, heat, light, current or magnetic field.
This transformation of material over
time is the fourth dimension. This means that 4D printing technology combines
3D printing, smart materials and customized design that is required for
transformation. In this type of printing, the structure of the object can be
preprogrammed as desired and designed to assemble itself.
Difference between 3D printing and 4D printing
The following are the differences
between the two types of printing:
The 3D printing technology involves
new manufacturing techniques, such as FDM
(Fused Deposition Modeling) and SLA (Stereolithography), as opposed
to conventional manufacturing methods, such as CNC machining, casting, plastic
injection, etc. These 3D techniques produce objects whose shape is permanent
and will remain unchanged after production.
Although 4D printing technology also
uses the techniques of 3D printing, the objects so created with advanced
materials and customized designs have the capability for structural
transformation. However, exposure to external stimuli, such as water, heat,
current or light, is needed to commence the deformation phase.
The types of materials used for
layer upon layer process differs between the two types of printing. In 3D
printing, the end product can either be rigid or flexible, that is, capable of
regaining shape once the load is removed from it. This is much like a rubber
band that can be stretched, but comes to its original form, when at rest.
In 4D printing, the smart material
transforms itself under exposure to stimuli. The smart structure can be of two
types – the rigid materials can be wholly made from expandable materials or may
be connected with expendable elements. Once these expendable elements get
exposed to certain stimuli, they change shape by moving or rotating, thereby
transforming into a new shape. Such smart materials include hydrogel, which is
capable of absorbing a large quantity of water and expand, and polymeric
material that can return to its original shape from a deformed state.
● Size of the
The size of the object created with
the help of 3D printer depends upon the size of the printer. However, in 4D
printing, the size of the object can exceed the printer’s dimensional
limitations. To understand how this takes place, imagine flat cardboard and a
folded cardboard. In 3D printing, you will need to directly print a folded
cardboard, whereas, through 4D printing, you only need to produce a flat object
that later transforms itself into a folded cardboard.
Whereas 3D printing technology has
proved to be highly versatile and efficient with regard to design, fabrication
and applications, 4D printing has potential to add value in certain
applications. It may never become as mainstream as ‘normal’ 3D printing, but it
will be interesting to watch its development, as well as the impact it has on
the area of smart materials.