Aluminium is one of the most useful printed metals and one of the more difficult ones to print. It reflects and conducts heat well, which is exactly what a laser powder bed process does not want, so the alloys used in printing are a narrow and specific set chosen for how they behave in a melt pool rather than for how they behave in a bar.
The alloys that print
Aluminium silicon casting alloys dominate because they solidify with a narrow freezing range and resist hot cracking, which is what kills most wrought alloys in a melt pool. Higher strength printable aluminium alloys exist and are a genuinely active area of development. What you cannot generally do is ask for the same wrought grade you would machine from and expect it to print.
Properties and heat treatment
As built printed aluminium has a very fine microstructure from rapid solidification and can be stronger than the same alloy cast. Stress relief is standard, and a full solution and ageing treatment is applied where properties matter. Porosity, if any, limits fatigue life, and hot isostatic pressing is used where fatigue is critical. None of this is optional if the part is structural.
Where it wins
Heat exchangers and cold plates with internal channels no drill can produce. Lightweight brackets from topology optimisation, where mass costs fuel or inertia. Consolidated assemblies, particularly manifolds. Antenna and radio frequency components where the geometry is complex. In every case the argument is geometry, not material cost.
Where machining still wins
Anything simple, anything large, anything in quantity, and anything where a certified wrought temper is required. Aluminium is fast and cheap to machine, so the bar is high: a printed aluminium part has to be genuinely impossible or genuinely much better to justify itself against a billet on a fast machine.
Questions people ask about aluminum 3d printing service
Which aluminium alloys can be printed?
Mostly aluminium silicon casting alloys, chosen because they resist hot cracking in a melt pool. Higher strength printable alloys exist but the list is narrower than for wrought material.
Is printed aluminium as strong as machined?
Comparable and sometimes stronger as built because of the fine microstructure, and it is anisotropic and porosity sensitive. Structural parts get heat treatment and often hot isostatic pressing.
Why print aluminium rather than machine it?
Only for geometry: internal channels, topology optimised structures and consolidated assemblies. Aluminium machines quickly, so simple parts should be machined.
Does printed aluminium need machining?
Yes, on any surface that has to be accurate. Fits, sealing faces and threads are printed with stock and machined afterwards as standard practice.