Additive manufacturing

Additive manufacturing (AM), commonly called 3D printing, is the production of parts by adding material step by step, usually layer by layer, directly from a digital 3D model. It is the opposite of subtractive processes, which remove material from stock (machining), and of formative processes, which give material its shape with a mold or tool (casting, injection molding, forming).

The workflow starts with a CAD model, which is exported to a print format (STL, 3MF or sometimes STEP). In the preparation software, the part is oriented, supports are added and the model is cut into layers (slicing). After printing comes post-processing: removal of supports or powder, cleaning, post-curing or heat treatment, and where needed machining of functional surfaces and surface finishing.

The ISO/ASTM 52900 standard divides additive processes into seven categories: material extrusion (for example FDM), vat photopolymerization (SLA and DLP), powder bed fusion (SLS, MJF and metal SLM or DMLS), material jetting (PolyJet), binder jetting, directed energy deposition (DED) and sheet lamination. The categories differ in available materials, accuracy, surface quality, part size and cost.

The main advantage is that no mold or tool is needed, the first part is available within hours to days, and geometric complexity adds little to the cost. Internal channels, lattice structures and assemblies consolidated into a single part are all possible. The drawbacks are a cost per part that falls only slowly with quantity, limited part size, visible layer lines on the surface and often different properties in the build direction (anisotropy).

Additive manufacturing is the natural choice for prototypes and rapid design validation, where it has largely replaced manual model making. It is also used for jigs, fixtures, gauges and assembly aids, for mold and tool inserts (rapid tooling), for spare parts made on demand, and for products customized to individuals, for example in dental technology or orthopedics.

For production parts, it pays off mainly at low quantities, for geometrically complex parts that would otherwise require several components or an expensive mold, and where lower weight brings savings in operation. Decide based on quantity, required material, accuracy and surface, not on whether the part is technically "printable".

A common mistake is to print a part designed for machining or injection molding without changes and compare only the price. The full benefit comes only with design for additive manufacturing (DfAM): orientation relative to the layers, as few supports as possible, lightweighting, uniform wall thickness and holes for removing powder or resin. Complexity is not entirely free either, because supports and finishing operations can make up a substantial share of the cost and lead time.

Do not confuse the properties of printed and production parts. Even in the same type of plastic, a print has different strength, elongation and aging resistance than a molded part. In your request for quote, state the process or at least the purpose of the part, the material, critical dimensions with tolerances, surface requirements and quantity. For STL data, check that the tessellation is fine enough that curved surfaces do not come out faceted.