SLM

Step 1

Printing

The SLM process begins with spreading a thin coat of metal powder across the build platform. The high powered laser selectively scans the powder bed, thus melting and fusing the metal powder together according to the cross sectional pattern in the 3D geometry. Once the pattern is complete, the build platform drops down by the designated layer height and an another layer of metal powder is spread across the previous one and the laser then scans subsequent layer. This process is repeated until all layers are melted and the final geometry is complete.

Step 2

Post Printing

The build chamber is removed from the printer and placed in the machine's de-powdering station. The build plate is raised to lift the part out of the chamber and all unsintered powder is brushed and blown away from the parts which are anchored to the build plate by the support structures. The unsintered powder is reclaimed and 100% of it can be used in future builds. The part(s) are then separated from the build plate either by a saw or Wire EDM. The build plate is then resurfaced before it can be used again. With their supports still intact, the parts are then de-stressed in an inert furnace to release any metal tension.

Step 3

Support Removal

Manual Removal: Support structures are typically part of the part and must be cut off with saws, grinders, or CNC machining. Soluble Support Removal: Non-applicable Manual Cleaning Note: Removal often requires specialised tools or wire EDM due to the strength and density of metal supports.

Step 4

Surface Finishing

Sanding / Polishing: Applied after support removal. Polishing can be performed in a vibratory finishing system. Chemical Smoothing / Coating: Options include electropolishing or chemical etching to smooth and passivate surfaces. Painting / Priming: Rare, but can be used for cosmetic purposes or corrosion protection. Gloss / Matte Control: Controlled via polishing or coatings; untreated surfaces are typically matte or rough.

Step 5

Curing / Heat Treatment

UV / Thermal Curing: Non-applicable. Annealing / Stress Relief: Essential. Parts undergo thermal treatment (e.g., 2–4 hours at 600–800°C) to relieve internal stresses from the printing process.

Step 6

Assembly and Functional Finishing

Gluing or Bonding: Rare; welding or mechanical fastening is most common. Drilling / Tapping / CNC: Common and often necessary; tight tolerances and smooth fits are usually achieved through secondary CNC machining. Inserts / Fasteners: Threaded inserts or direct metal threads are common for assemblies.

Step 7

Special Treatments

Infiltration / Sealing: Non-applicable; parts are fully dense or nearly so post-sintering. Functional Coatings: Options include anodising (aluminium), passivation (stainless), PVD/CVD coatings, and plating for wear, corrosion, or conductivity. Post-print Functionalisation: HIP (Hot Isostatic Pressing) is frequently used to eliminate internal voids and improve fatigue resistance; surface treatments may also include shot peening or hardening.