3D printing

Updated Thursday, 8th March 2018
Although often used as a blanket term for additive manufacturing, 3D printing is a technique where a print head is used to control the deposition of polymer on a substrate drop by drop.

As the name suggests, the process works similarly to traditional 2D printing. Material is added drop by drop rather than layer by layer, by controlling the flow of material using piezoelectric flow restrictors similar to those used in standard desktop inkjet printers. As drops are deposited on top of previous drops, three-dimensional structures can be formed.

Images to demonstrate '3D printing' - see article


The process can be summarised as follows:

  1. A control system positions the print head above the position requiring material addition.
  2. Droplets of material are deposited from the print head onto the surface where required.
  3. As material is added and solidified drop by drop the first layer is created.
  4. Further layers are built up on top of previous layers by increasing the height of the print head.
  5. After deposition, post processing often includes removal of support material or UV curing.


  1. Proven for a limited range of polymeric materials. The formation of a droplet depends on sufficient viscosity in the polymer melt. This limits application to specific polymers. Fortunately, several common and popular polymers fit into this requirement. For instance:
    • polypropylene
    • HDPE
    • PS
    • PMMA
    • PC
    • ABS.


  1. Specific benefits include:
    • Capable of multiple material and multiple colour printing. 
    • Extremely fine drop production permits very fine detail to be printed.
  1. Component design is limited by:
    • Strength and thoroughness can be influenced by many factors including time of build, atmosphere and even polymer colour.
    • Overhanging regions need extra designing.
    • Support structures can only be placed where they can be removed (i.e. not inside internal voids like those required to create a ball).

See Also: Direct metal deposition (DMD)Fused deposition modelling (FDM)Selective laser melting (SLM).

This article is a part of Manupedia, a collection of information about some of the processes used to convert materials into useful objects.


Become an OU student

Ratings & Comments

Share this free course

Copyright information

For further information, take a look at our frequently asked questions which may give you the support you need.

Have a question?