There is a piece of conventional wisdom in additive manufacturing that says you can print whatever you can design. It is mostly true, and it is also mostly unhelpful. The freedom to print anything does not tell you what you should print. Design for Additive Manufacturing, usually shortened to DfAM, is the engineering discipline of designing parts that exploit AM's strengths and avoid its weaknesses.
Done well, DfAM delivers parts that are lighter, stronger, cheaper to print and easier to assemble. Done poorly, AM just produces poorly machined parts at machined-part cost. Our FDM service sees both every week.
Avoid sharp corners and unsupported overhangs
Internal sharp corners are stress concentrators in any technology, but they are particularly weak in additive parts because they coincide with layer-to-layer interfaces. Generous radii of three millimetres minimum, five millimetres or more where space allows, reduce stress concentrations and improve print quality at the same time.
Overhangs steeper than forty-five degrees from vertical typically need support material, which adds print time, increases material use and degrades the underside surface finish. Reorient the part, redesign the overhang with a chamfered transition, or split the geometry into sub-assemblies if the overhang cannot be avoided.
Wall thickness, feature size and the print process
Specify wall thicknesses as multiples of the print extrusion width, not as legacy machining specifications. A 1.6 mm wall built from four 0.4 mm extrusions is dramatically stronger than a 1.5 mm wall built from three full extrusions plus a partial bead. Aligning the design with the print process is a free engineering win.
Minimum feature size depends on the process. FDM resolves features down to about 0.4 mm with a 0.4 mm nozzle. SLA can reach 0.05 to 0.1 mm. Designing features below the resolution of the process you actually use produces unreliable results.
Generous internal radii, three millimetres minimum,
Self-supporting overhangs no steeper than forty-five degrees from vertical,
Wall thicknesses as integer multiples of extrusion width,
Feature sizes that respect the chosen process resolution,
Print orientation specified on the drawing, never assumed.
Print orientation is a design decision
Print orientation is not a slicing decision. It is a design decision that determines which loads the part carries well, where surface finish will be best, where support material will land and how long the print will take. In-plane loads always outperform interlayer loads, often by a factor of three or more in tensile and bending performance.
Documenting the intended orientation as part of the design release is one of the highest impact DfAM practices we know. We have seen identical files print perfectly in one orientation and fail repeatedly in another, with the difference being a slicing choice that was never communicated to the shop.
Consolidate parts whenever you can
AM's most distinctive advantage is the ability to consolidate multiple machined parts and assemblies into a single printed component. Brackets that were three pieces and six fasteners become one print. Housings that were two halves with an O-ring become integrated with a captive seal. Consolidation reduces assembly cost, improves reliability and often delivers better mechanical performance than the parts it replaces. The work in our portfolio leans heavily on this principle.