An introduction to 3D printing

Oct 14, 2019 6:00:00 AM

3D printing technology (also called Rapid Prototyping) is an additive computer-controlled processes that builds parts inside a machine, layer by layer, using a variety of materials and processes. 3D printing can produce physical prototypes directly from the computer. The invention came around the same time as CNC technology in the late 1980s. Although is not as popular as CNC, 3D printing has transformed our ideas of prototype making. This ability has a promising push forward in product development. In addition, 3D printing has a special advantage in complex models, inner flow channel designs, cavity designs, thin walls, and ribs which are difficult to make by any other method.

 

How 3D printing Works: 

The steps in 3D printing is as follows:

Step 1: Design file

 

To start, we have to create a blueprint or three-dimensional digital file of the object we want to print. The most common way to do this is with a Computer Aided Design (CAD). However, there are other professional and entry level softwares that can produce such files. Some ways to do this are 

  • 3D modelling software  such as Blender, Sketchup, Autocad, Solidworks can also be used to create a 3D printable file. 
  • 3D Scanning - Using a 3D scanner, this technology involves analyzing a real-world object and creates a digital replica. After this we can modify it before printing. 
  • Downloads - Or you can choose to purchase/download existing files 

There are some specific design requirements for this wot work, so also be aware of the design requirements.

 

Image result for 3d printing design file

 

 

Step 2: File Formatting

 

Before sending the CAD design to the printer, it must be converted to an appropriate format. The most common one being STL format, which stands for StereoLithography format. 

Other alternatives include .OBJ and .3MF. Although those do not contain color information. For 3D printing in full color, use file formats like .X3D, .WRL, .DAE and .PLY 

Not every STL or OBJ file is 3D printable by default, it has to meet certain criteria such as water-tightness, proper physical size, etc. 

 

Step 3: Slicing 

 

Slicing involves dividing or chopping the 3D model into several horizontal layers through several steps. After slicing, a new file format is formed: G-code, with file extension .gcode. G-code is the most widely used numerical code programming language in computer-aided manufacturing to control automated machine tools like 3D printing and CNCs. 

 

Image result for 3d printing slicing

 

 

Step 4: Printing 

 

The printing machines are made of many moving and intricate parts, and they need correct maintenance and calibration to produce successful prints. The printing machine will follow the automated G-code instructions and does not need to be monitored once the printing starts, as long as there is no software error or the machine running out of raw materials. 

 

Step 5: Removal 

 

This process is to remove the finished parts from the printer. This varies among different 3D printing technologies. For Desktop machines it is simply separating the print from the build platform. For some industrial 3D printers, it requires a technical process with professional skills and specialized equipment in a controlled environment.

 

Step 6: Post-Processing 

 

This also vary among different 3D technologies and the materials used. Some allow us to handle the finished parts straightaway, others require additional steps to finish the fabrication process. 

This step is specifically important for the aesthetic and function of the parts. 

Most of the time 3D printed parts are rough and do not have a finished feel. This can be enhanced with methods such as sanding, painting, polishing, etc. To improve mechanical properties many industrial processes can also be used.

This may seem like a time consuming process but as the technology develops, these steps can be automated with ease. 

 

 

 

 

Different Kinds of 3D Printing:

According to ISO/ASTM 52900:2015(en)Additive manufacturing — General principles — Terminology, we can find the following Process categories: 

  • Material extrusion (FDM): Material is selectively dispensed through a nozzle or orifice
  • Vat photopolymerization(SLA,DLP): Liquid photopolymer in a vat is selectively cured by light-activated polymerization
  • Powder bed fusion(SLS,SLM): Thermal energy selectively fuses regions of a powder bed
  • Material jetting(MJ): Droplets of build materials are selectively deposited
  • Binder jetting(BJ): Liquid bonding agent is selectively deposited to join powder materials
  • Directed energy deposition(LENS,LBMD): Focused thermal energy is used to fuse materials by melting as they are being deposited
  • Sheet lamination(LOM,UAM): Sheets of material are bonded to form a part

     

The following can give you some basic guide to choice which kinds of 3D printing meet your requirements.

 

                                   3D Printing Vs Traditional Manufacture 

When processing a part, we have a choice between additive technology(3D printing) ,subtractive technology(CNC, milling, lathe, Wire cutting) or formative manufacturing technology(Injection molding). Each has its own advantages and disadvantages. 

 

Cost:


    • Additive technology has an advantage in prototype testing or Customized parts.
    • Subtractive technology is typically more economical when making parts in the 100 pc range;
    • Formative manufacturing has an advantage in mass production.

      Geometry
    • Additive technology can have a complex geometry(inner flow channel, cavity, thin wall, and rib );
    • Subtractive technology has limitations in terms of geometry. For example CNC can't process inner flow channel which bend by itself;
    • Formative manufacturing has more flexibility in terms of geometry. For example injection needs draft angle in molding. In addition injection molding can't make complex inner flow channel.

      Material:
    • Additive technology has requirements in materials as every machine would require specified materials. For example FDM 3D printing normally uses ABS and PLA. Each part has its own effects. 
    • Subtractive technology can process almost every solid, for example metal, plastic ,wood, etc;
    • Formative manufacture process mainly plastic materials. 

    Quality: For quality,subtractive technology is normally similar with formative technology and they are better than additive technology. 

     

  • Size:

    • For Additive technology, the small the part, the better
    • Subtractive technology and formative technology 's sizes could be much bigger than additive technology 

 

 

Looking for 3D printing solutions? 

NexPCB got you covered

We offer various 3D printing services: FDM, SLM, SLA and SLS

All with trusted quality, quick lead time and reasonable prices

Just send us your project requests below 

 

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For our next post, we will be discovering FDM 3D printing. Click here.