Process parameters development is a rigorous multi-step process paramount to manufacturing repeatability and reliability of production. Amongst ensuring high density, suitable surface roughness and reliable mechanical properties, dimension accuracy and precision must also be guaranteed as part of the ideal (ie no mechanical post processing involved) AM process. Here, we review the critical factors that can be used to ensure dimension accuracy.
Various factors can be responsible for low dimension accuracy of as-built SLMed components:
1. Large surface roughness makes it difficult to measure dimensions accuracy;
2. Internal stresses can distort the product;
3. Incorrect laser processing parameters or machine settings can cause discrepancy between CAD and SLMed product dimensions;
4. Digitalisation (mostly for small features such as holes)
In addition, accuracy susceptibility varies with the type and size of features to be processed.
This is why understanding the machine and laser/material interactions is critical.
Here we assume surface roughness is Ra<10um and that internal stresses are minimal to discuss processing parameters and machine settings needed to ensure high dimension accuracy of large components (ie small features accuracy will be discussed separately).
Processing parameters: understanding actual track width
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