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DESIGN GUIDELINES FOR SLS

Additive manufacturing (AM) evolved from Rapid Prototyping (RP) to the end-of-use product manufacturing process, as the industry solved manufacturing constraints. Part consolidation, reduction of assembly time and part count was only possible due to the design freedom offered by Additive Manufacturing. DFAM or Design for Additive Manufacturing is different from designing for traditional manufacturing such as milling, sheet metal or molding. The use of Topology Optimization provides the optimum material layout according to design space and loading case in which design variables are defined as a fictitious density for each element, and these values are varied from 0 to 1 to optimize the material distribution.

Function integration and structure optimization generates reinforcements through lattice structures according to performance requirements.

Additive Manufacturing designer needs to have a good understanding of the technology that will be used to manufacture the part, achievable tolerances, impact of shrinkage and warpage…etc.

Additive manufacturing drives new frontiers offering designers more opportunities for innovation.

DESIGN GUIDELINES 

wall thickness A minimum of 1mm wall thickness is recommended but between 1.5mm and 3mm will provide more accurate and durable walls
Ensure the wall thickness is consistent throughout the part to reduce deformation during the shrinking process
Clearance  A minimum of 0.5mm clearance is recommended between features
 Hollows Confined hollow spaces must be removed because they retain un-sintered powder. Adding in at least 2 clean-out ports that are 6mm or larger will allow us to remove that powder.
Fillets It is recommended whenever possible to opt for fillets instead of sharp corners. This will aid in the cleaning process and reduce acute stress points.
Platform Size Our largest printers are 30x30x45cm large (X, Y, Z)
Text The font must have Bold applied and use a font size no smaller than 14. The font size must be at least 0.8mm deep
Holes Hole diameter is dependent on wall thickness; however, 1.5mm is considered the minimum hole size. Thicker parts require larger diameters
Accuracy For the SLS process, it is only possible to build with symmetric tolerances
Our standard production tolerances (with no post-op machining processes) are +/-0.25mm (+/-0.010 inches) for features less than or equal to 50mm in size, +/-0.38mm (+/-0.015 inches) for features that are greater than 50mm in size but less than or equal to 75mm in size. For features that are greater than 75mm in size our tolerance is +/-0.38mm plus 0.05mm per every 25mm over 75mm (+/-0.015 plus 0.002 inches per inch for each inch over 3.00 inches)
High Resolution  High resolution printing in 100 micron layer thickness provides less apparent build lines and smoother parts. However, this requires a smaller laser diameter which means increased build time. The part will have finer details and higher accuracy
Mid Resolution  Mid resolution printing in 120 micron layer thickness can have some visible built lines, however the parts will have slightly higher mechanical properties. This printing resolution has a faster turn around time; especially for low volume production