Additive Manufacturing Process: A Simplified Explanation

The Generic AM Process

Additive Manufacturing (AM) involves a number of steps that move from the virtual CAD description to the physical resultant part. Different products will involve AM in different ways and to different degrees. Small, relatively simple products may only make use of AM for visualization models, while larger, more complex products with greater engineering content may involve AM during numerous stages and iterations throughout the development process. Furthermore, early stages of the product development process may only require rough parts, with AM being used because of the speed at which they can be fabricated.

At later stages of the process, parts may require careful cleaning and post-processing (including sanding, surface preparation, and painting) before they are used, with AM being useful here because of the complexity of form that can be created without having to consider tooling. Most AM processes involve, to some degree at least, the following eight steps.

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Step 1: CAD

All AM parts must start from a software model that fully describes the external
geometry. This can involve the use of almost any professional CAD solid modeling
software, 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: Conversion to STL

Nearly every AM machine accepts the STL file format, which has become a de
facto standard, and nowadays nearly every CAD system can output such a file
format. This file describes the external closed surfaces of the original CAD model
and forms the basis for calculation of the slices.

Step 3: Transfer to AM Machine and STL File Manipulation

The STL file describing the part must be transferred to the AM machine. Here, there
may be some general manipulation of the file so that it is the correct size, position,
and orientation for building.

Step 4: Machine Setup

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

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.

Step 6: Removal

Once the AM machine has completed the build, the parts must be removed. This
may require interaction with the machine, which may have safety interlocks to
ensure for example that the operating temperatures are sufficiently low or that there
are no actively moving parts.

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.

Step 8: Application

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. Treatments
may be laborious and lengthy if the finishing requirements are very demanding.
They may also be required to be assembled together with other mechanical or
electronic components to form a final model or product.

Conclusion

While the numerous stages in the AM process have now been discussed, it is
important to realize that many AM machines require careful maintenance. Many
AM machines use fragile laser or printer technology that must be carefully monitored and that should preferably not be used in a dirty or noisy environment. While
machines are generally designed to operate unattended, it is important to include
regular checks in the maintenance schedule, and that different technologies require
different levels of maintenance.


Based on my research

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