Additive Manufacturing
By DarthVader
Date: 2022-07-15
Topic: 150 see comments
Post views: 1089
Additive Manufacturing
Conventional manufacturing methods such as casting of metals or injection moulding of polymers are, at present, far less costly than additive manufacturing for mass production.
However, AM is more flexible, and quicker and less expensive when producing a small number of parts. AM also has the unique capability of producing complex shapes or geometries that might be very difficult, if not impossible, to make using conventional manufacturing methods.
Types:
Selective laser sintering (SLS)
Video: https://youtu.be/OjjczQkK2zM
- SLS machines use a laser to melt and fuse powder particles layer by layer to create shapes which can be complex.
- This technique is even applied to aerospace-grade titanium alloys, stainless steels and also nickel-based superalloys (high performance alloys).
- SLS is probably the additive manufacturing process with the most potential for making highly durable finished parts.
- As the powder reservoir effectively scaffolds the isolated parts, there is no need for post-processing to remove unwanted parts.
- There is no reason in principle why any material can't be used in SLS.
Stereolithography
- Stereolithography is an additive process in which a UV laser beam is used to set off a chemical reaction in a bath of liquid UV-sensitive resin (a liquid polymer), causing it to solidify.
- The laser beam traces out the shape of each layer on the surface of the pool of resin above a moving platform. Once the first layer is formed, the platform moves down by the depth of one layer before a new coat of liquid resin is applied on the newly formed surface.
- The next layer is then traced out and solidifies directly onto the layer below.
- The entire geometry of the machine can be inverted so that the developing part is raised out of the reservoir of liquid rather than lowered into it.
Laser metal deposition (LMD)
Video: https://youtu.be/yKnlmfuMSgo
LMD is similar to selective laser sintering in that it also uses powder. But whereas SLS uses a powder bed, laser metal deposition instead has the powder fed through a nozzle.
- The part is formed in layers and is made on top of a rotating bed which can tilt, the bed rotates as the nozzle builds up the part layer by layer.
- The process creates less waste material than SLS, but it is not suitable for some shapes with floating parts or holes, and so SLS may be the better choice in some cases.
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