Imagine a full-sized ship or an aeroplane made out of automated systems with correct precision, like a printed entity, and having minimal human effort! Sounds crazy, right?
But this may be a possibility in the not-so-far future! And all credit goes to the groundbreaking phenomena of 3-dimensional printing or 3-D printing. This technology has created quite a massive stir across several industries over the last few decades, with automation gaining dramatic popularity.
A technology which can generate life-sized objects with accuracy, almost similar to a computer printer printing a sheet of paper! Well, here we have countless other boons of computational technologies and automation.
Johannes Gutenberg introduced the printing press technology as early as 1440, and since then, printing has evolved dramatically. 3D printing, or generating real-life three-dimensional objects, was conceived in the 1940s and 1950s.
However, it was not before 1984 that Chuck Hull of 3D systems Corp. created history by successfully developing a fully working 3D printer and obtaining a patent for worldwide commercial usage. Now, let us go deeper into the matter.
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The Process Of 3D Printing
3D printing, as the name suggests, is the process which can create life-sized real objects from preset models using automated manufacturing technologies. After giving all necessary inputs regarding CAD files and desired model representations to the mechanism, there is not much human intervention required. The entire process is considered analogous to the technology of printing.
How does a 3D printer automatically work?
It is not like an entire sculpture, or a pair of shoes will pop out of a device like a photocopier, laser printer, or even a popcorn machine that you are used to seeing in movie theatres! It is completely unrealistic! Neither does it work on the classical technique of ‘carving’ from a single block of molten plastic, wood, or metal and gradually forming the shape, also known as “subtractive manufacturing.”
Much like its name, a 3D printer mainly works on the principle of conventional inkjet printing itself. It builds or raises a structure or an object by adding materials, treating them, and materialising the right texture or configuration layer after layer for all practical purposes. Hence, it can also be seen as a method of “additive manufacturing.”
A 3D printer involves a system of connected mechanisms, which may feel similar to that seen in production assembly lines or manufacturing units, though much smaller.
The configuration and complexity of a 3D printer may vary based on requirement- sometimes, it may be as small as a wine refrigerator or as large as a series of supercomputers; sometimes, it may have just a single robot arm or a set of multiple arms and other complicated systems.
The work is also not that difficult to understand. A 3D printer builds out an object layer by layer, as mentioned above, by incorporating the right amounts of raw materials placed, of course.
The raw materials are usually ejected through nozzle-like outlets of various types resembling glue guns in definite preset amounts and flow rates. The entire trajectory of operation of the mechanical arms is under computer control.
The principle can also be best imagined by simply visualising a loaf of bread cut into slices. Here, it is completely reversed. A 3D printer works on moulding all required slices layer after layer by repeatedly printing and working over the same area till completion and then forming the whole object in a bottom-up sense. Or rather, in simple terms, glue back individual slices of bread to create a larger loaf.
This bottom-up sense of orientation is also known as extrusion in technical terms. The main idea behind 3D printing can also be derived from underground rock formations layer by layer over the years.
Now, making every layer is complicated, unlike a simple loaf of bread. This principle of layer-by-layer formation of a 3D object is technically known as stereolithography; something owed to Hull as well.
Step-by-Step process of 3D printing
This is the first and foremost step, like any other automated or computational technology. A schematic representation or blueprint of the desired object is generated using CAD packages. This may be initially represented as a 2D file and later transformed into 3D.
The model is assessed carefully, and any errors or discrepancies are rectified. These models are often saved digitally as Stereolithography File Format or STL. Modern technologies also use updated formats like Additive Manufacturing File Format or AMF.
Pre-processing and Preparation of the printer
After creating the 3D blueprint or model, the file is transferred to the machine input end for incorporation. The machine reads the file and stores it in its system drives electronically. Then the printer system is prepared. All required raw materials are filled, like plastic, metals, binders, resins, etc.
All 3D printers have pre-installed high-end software for reading the files. The printer’s pre-programmed software further checks any issues in the STL file, like defects, geometric imperfections, discontinuities, gaps, holes, breaks, breaks, self-interactions, or any other anomalies.
After approval of the final model in STL, the software then simplifies the model into simple layers or individual “slices”. This is essentially similar to the process of meshing in structural analysis software. The printing interface also sets the sequence of operation. After all this, the final set of instructions is generated as a G-code file which is common for all Computer-Aided Manufacturing systems.
The competence of the software is very important as the entire job takes place based on the code file sent. Any minute error can make the model fail and resemble a badly squashed birthday cake!
Final Preparation of the Object
There is not much to do at our end after the above. The mechanism is finally instructed to proceed by hitting the “Print” button on our computers. Then the printer follows the same sequence of operations and trajectory of processes to yield the final item.
Everything like the selection of the raw materials, ejection of the precise amount of materials at the right time with the flow, the trajectory of the arms over the object, intervals between two successive layers, and so on is fully scripted or as per the algorithm set by the printer based on the blueprint and STL file.
The space between them is fused for every two successive layers using adhesives, binders, or in-situ heat treatment technologies like laser beams or UV radiations. Usually, the drying time is short, and the printing arms move on to the next successive layer or cross-section after a short period once the preceding layer solidifies.
Different Techniques in 3D printing and type of printers
While the primary governing principle remains the same, the techniques for printing 3D objects can be of various kinds. The most common and widely used one is Fused Deposition Modeling/ FDM.
This involves casting out liquid material at controlled rates over the same area over and over again until and unless it hardens to form successive layers over one another. This principle entirely uses the classical principle of extrusion and is used by most 3D printing works. Extrusion nozzle heads control the heating and adjust the flow rates.
The nozzle heads are powered by motors which control their movements, the material flow rates, and the temperatures. As mentioned above, the CAD file specific to FDM is processed by the system to generate CAM file data which is then taken as the source. However, FDM does not apply to some complex geometries and specific materials.
Granular material binding is another similar method to FDM, where materials selectively impinge into the granular bed. After the layer is bonded, it is pushed down, and the process is repeated for other layers until the object is built up.
Direct Material Laser Sintering, Selective Laser Melting, and Electron Beam Melting are other advanced techniques that use external heating sources to produce harder objects, especially suitable for metals and complex geometries.
Some 3D printers are material jetting, binder jetting, powder bed fusion, directed energy deposition, sheet lamination, and vat polymerisation.
Future of 3D Printing and Use in the Shipping Industry
3D printing has many advantages and a promising future. They are faster, accurate, safer, and do not require much human effort. Though the process is expensive and often has limitations, several sectors, including defence, manufacturing, aviation, and even healthcare, are resorting to seeking greater applications of 3D printing. As per reports, it is already a 3-billion-dollar industry annually and is expected to rise further.
As far as the marine industry is concerned, 3D printing is already being used to manufacture several items like propeller parts, appendages, etc. In the future, the industry is looking forward to more applications in the construction of ships and submarines.
One of the advantages is that if this method is utilised smartly, fundamental components can be built without the requirement of much assemblage. In this way, it can save time and prove to be cost-effective. The 3D-printed blocks can then be joined together.
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Subhodeep is a Naval Architecture and Ocean Engineering graduate. Interested in the intricacies of marine structures and goal-based design aspects, he is dedicated to sharing and propagation of common technical knowledge within this sector, which, at this very moment, requires a turnabout to flourish back to its old glory.