3D Printing is the future of manufacturing physical products; therefore, it is imperative that everyone, especially technical students, engineers, product development managers, and entrepreneurs, understand the 3D printing process.
3D printing encompasses a wide range of distinct technologies, such as fused deposition modelling, stereolithography, digital light processing, selective laser sintering, and many others; however, the fundamental concept of producing parts by building them up layer by layer has not changed. For the purpose of providing an explanation, we will now demonstrate how a SLA 3D Printing process works.
The 3D Printing Process
Step 1: CAD Model
The first step in the 3D printing process is typically to create a 3D digital model of the object you want to print using CAD modelling software (Catia, Fusion360, Solidworks, Creo, etc.) or a 3D scanner, or even photogrammetry software. This digital model will serve as the blueprint for the physical object to be created by the 3D printer. Once the digital model is complete, it must be converted into a 3D printer-compatible format, such as an STL file. The STL file contains a set of instructions that instruct the printer on where to place each layer of material to construct the final object. Once the STL file is ready, it can be sent to a 3D printer, which will use the data to build the object layer by layer with the appropriate material. Note that STL is not the only format and other formats like STEP, IGES & OBJ are also widely used.
Step 2: Slicing
The second step in the process is to prepare the model for printing. This involves the use of a slicing software which helps you control the printing parameters to ensure the print is successful and is printed the way you want. The slicing software or Slicer, literally slices the 3D model into multiple layers depending on the specifications you provide. These slices (also called as layers) are then deposited one above the other during the actual printing process. The slicer converts the design into co-ordinates which the printer understands and the material is deposited as per the co-ordinates.
In the slicer software, it is firstly important to configure your printer and materials so that the software knows the build boundaries, the nozzle diameter and material diameter and a mistake in this can lead to a failed print. In here, you can define printing parameters like the layer thickness, wall thickness, printing speed, extruder temperature, bed temperature, retraction settings, use bed adhesion tools and much more.
The output of this slicer is in the form of a text file with a file extension being ‘.gcode’. This file has a large set of instructions for the printer and basically tells the printer how to print the object as per the parameters set in the slicing software.
Step 3: Setting up the Machine
This step is often not talked about much as it is assumed that users will know about it. And even though it is obvious that you should ensure your machine is ready, most beginners fail to set up the machine. So, before you start printing, ensure your build plate is clean, is dry, it does not have any earlier material residue. Also ensure you have the appropriate material loaded in the machine. The appropriate filament in case of FDM printer, the appropriate resin in case of resin 3D printer, appropriate powder in case of SLS 3D printer and so on.
Additionally, sometimes the materials need a bit of preheating, especially in FDM and SLS printing, and while the gcode file may have that instruction, this can also be done manually to be extra cautious and increase the chances of a successful print. The preheating can eliminate and residual moisture from the material.
Step 4: 3D Printing
The printing process is started after the 3D printer has been prepared and the appropriate settings have been configured. The 3D printer reads the gcode file generated by the slicing software and begins layer by layer construction of the object. Depending on factors such as the complexity of the object, the size of the print, the type of material used, and the resolution and speed of the 3D printer, the printing process can take anywhere from a few minutes to several hours or even days.
Depending on the technology, the printer will either extrude the material, cure the resin or fuse the powdered particles and form the layer.
How 3D Printing Works?
3D printing is a type of additive manufacturing technology that creates 3D objects by layering materials. 3D printers work in the same way that inkjet printers do. 3D printers, unlike inkjet printers, use different types of materials rather than ink. Polymers, metals, ceramics, composites, concrete, bioinks, and other materials may be used. To make a physical object, the material is deposited in layers.
Below is the basic 3D printing process and the step-by-step explanation of how an SLA 3D printer works.
1. Laser Source: First and foremost, a laser source emits a laser beam. This laser beam helps to solidify the liquid material to form the final three-dimensional object.
2. The Elevator: The main function of this elevator is to help lay the layers. This elevator moves up and down thereby raising and lowering the platform in order to help lay the layers of object
3. Vat: The vat is a vessel like structure which contains or stores the liquid material.
4. Layered Parts: This is the actual 3D printed object that is created when the material is deposited one-by-one or in layers on top of each other
5. Material: The material (called resin in case of SLA and DLP printers) is the substance which is used to create an object. There may be different forms of resins used such as tough resin, dental resin, flexible resin, etc. Other printers like FDM & SLS use different materials. Today, a lot of different materials are used in 3D printing. Some of the materials used in 3D printing include gold, silver, ceramics, biomaterials and food.
Step 5: Post Processing
The last step in the 3D printing process. When the printer comes to a halt, the print must be removed from the bed. This process varies depending on the technology used. In case of resin 3D printing, the resin material, at first, has to be allowed to drained into the resin tank. Once the part does not drip the liquid material, the part is passed through the washing and curing station where the excess material is washed in Iso Propyl Alcohol (IPA) and the part is cured in a UV chamber to increase its strength. Kindly ensure you are using gloves and a mask at all times as the resin materials are toxic and you should not inhale these fumes that are generated during the printing process.
In case of an FDM printer, the first step is to remove the print from the build plate by simply pulling the print, or using a scrapper or by bending the build plate (only works if you have a flexible plate). Even after the print is removed, the part must go through some post-processing steps like support removal, sanding, priming and painting, etc., depending on what type of output you need. In other technologies, the post-processing techniques also include sand blasting, annealing, etc.
So, the post-processing steps vary depending on the technology you have used to print the part as well as the final output you desire like smooth finish, colouring the part, increasing the part strength and more.
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