ADDITIVE MANUFACTURING PROCESS STEPS

AM PROCESS STEPS

Additive Manufacturing involves a number of steps that move from the virtual CAD (Computer Aided Design) description to the physical resultant part. Different products will involve Additive Manufacturing in different ways and to different degrees. Small, relatively simple products may only make use of Additive Manufacturing for visualization models, while larger, more complex products with greater engineering content may involve Additive Manufacturing during numerous stages and iterations throughout the development process.

All the Additive manufacturing processes have the following eight common steps-

Step 1- 3D model creation

Step 2- STL file creation

Step 3- STL file transfer

Step 4- Machine set up

Step 5- Build

Step 6- Part removal

Step 7- Post processing

Step 8- Applications

Step 1- 3D model creation

All Additive Manufacturing parts must start from a software model that fully describes the external geometry. This can involve the use of almost any CAD solid modeling software (e.g., Solidworks, CATIA, Solidedge, Abaqus etc.), but the output must be a 3D solid or surface representation. Reverse engineering equipment (e.g., laser and optical scanning) can also be used to create this representation.

Step 2- STL file creation

The CAD file is then converted to a standard AM file format called standard tessellation language (STL) or Standard triangle language, which was developed by 3D Systems in the late 1980s for use in its Stereolithography (SLA) machines.

The STL format specifies both ASCII and binary representations. Binary files are more common used in AM.This file format is supported by many other software packages it is widely used for rapid prototyping, 3D printing and computer aided manufacturing. STL files are generated from 3D CAD data within the CAD system. The output is a boundary representation that is approximated by a mesh of triangles. As the name suggests this will tessellate the 3D shape and slice the part into digital layers. The layer thickness dictates the final quality and depends on the machine and process.

Step 3- STL file transfer

Once a part has been converted to STL, there are only a few operations that can be performed. This is because the triangle definition does not allow for radical changes to the data. STL file is then transferred to the printer often using the custom machine software, where the model will be manipulated to orientate for printing. 

A variety of STL viewers is available, mostly as a free download an example is the Marcam STL view Like many other systems, this software allows restricted access to the STL file, making it possible to view triangles, apply shading, display sections.By buying a complete version of the program, other tools may be used, for example, to allow the user to measure the part at various places, to annotate the part, to show sliced information, and to identify possible data problems. At this stage, machine software might create its own file with extra information it needs to build the part such as support structure, temperature etc.

Step 4- Machine set up

The AM machine must be properly set up prior to the build process. Such settings would relate to the build parameters like the material constraints, energy source, layer thickness, timings, etc.

Step 5- Build

Once the build started, it gradually builds the design one layer at a time. A typical layer is around 0.1mm in thickness but depending on the technology and the material used it can go down to 20 microns.

Building the part is mainly an automated process and the machine can largely carry on without supervision. Only superficial monitoring of the machine needs to take place at this time to ensure no errors have taken place like running out of material, power or software glitches, etc. Depending on the build size, the printing machine, AM technology, material and the printing resolution, this build process could take hours or even days to complete.

Step 6- Part removal

Once the AM machine has completed the build, the parts or multiple parts in some cases may need a cooling-off period before the parts can be removed from the machine.

Step 7- Post processing

Once removed from the machine, parts may require an amount of additional cleaning up before they are ready for use. Parts may be weak at this stage or they may have supporting features that must be removed. This therefore often requires time and careful, experienced manual manipulation. Depending on the AM technology used and the end use of the part, it varies from simple cleaning and polishing to machining and heating treating the part.

Step 8- Applications

Parts may now be ready to be used. However, they may also require additional treatment before they are acceptable for use. For example, they may require priming and painting to give an acceptable surface texture and finish. They may also be required to be assembled together with other mechanical or electronic components to form a final model or product.