Post-Processing
The skill with which various AM practitioners perform post-processing is one of the most distinguishing characteristics between competing service providers. Companies which can efficiently and accurately post-process parts to a customer’s expectations can
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Post-Processing
Most AM processes require post-processing after part building to prepare the part for its intended use. Depending upon the AM technique, the reason for postprocessing varies. For purposes of simplicity, this chapter will focus on postprocessing techniques which are used to enhance components or overcome AM limitations. These include: 1. 2. 3. 4. 5. 6. 7.
Support Material Removal Surface Texture Improvements Accuracy Improvements Aesthetic Improvements Preparation for use as a Pattern Property Enhancements using Non-Thermal Techniques Property Enhancements using Thermal Techniques
The skill with which various AM practitioners perform post-processing is one of the most distinguishing characteristics between competing service providers. Companies which can efficiently and accurately post-process parts to a customer’s expectations can often charge a premium for their services; whereas, companies which compete primarily on price may sacrifice post-processing quality in order to reduce costs.
16.1
Support Material Removal
The most common type of post-processing in AM is support removal. Support material can be broadly classified into two categories: (a) material which surrounds the part as a naturally-occurring by-product of the build process (natural supports), and (b) rigid structures which are designed and built to support, restrain or attach the part being built to a build platform (synthetic supports).
I. Gibson, D.W. Rosen, and B. Stucker, Additive Manufacturing Technologies, DOI 10.1007/978-1-4419-1120-9_16, # Springer ScienceþBusiness Media, LLC 2010
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16 Post-Processing
16.1.1 Natural Support Post-Processing In processes where the part being built is fully encapsulated in the build material, the part must be removed from the surrounding material prior to its use. Processes which provide natural supports are primarily powder-based and sheet-based processes. Specifically, all powder bed fusion (PBF) and binder printing processes require removal of the part from the loose powder surrounding the part; and bondthen-form sheet metal lamination processes require removal of the encapsulating sheet material. In PBF processes, after the part is built it is typically necessary to allow the part to go through a cool-down stage. The part should remain embedded inside the powder to minimize part distortion due to non-uniform cooling. The cool-down time is dependent on the build material and the size of the part(s). Once cool-down is complete, there are several methods used to remove the part(s) from the surrounding loose powder. Typically, the entire build (made up of loose powder and fused parts) is removed from the machine as a block and transported to a “breakout” station where the parts are removed manually from the surrounding powdered material. Brushes, compressed air, and light bead blasting are commonly used to remove loosely adhered powder; whereas, wood-working tools and dental cleaning tools are commonly used to remove powders which have sintered to the surface or powder entrapped
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