5. Material extrusion
Material extrusion is probably the most known 3D printing technology by the mass market because it is the one used by small 3D printers that have reached an affordable price point for residential users. What we do not have is, generally, a captivating use case for keeping one of these 3D printer at home.
The printer uses a (thermo)plastic wire, a filament, that goes through a nozzle, gets heated and is extruded on a surface in subsequent layers, building the desired object.
The advantage of material extrusion is in its low cost and ease of use. On the other hand it is not as accurate as other additive manufacturing technologies, so it is rarely used in industrial applications. Also, the extruding nozzle should keep going, it cannot stop, otherwise the extruded material will create a bump.
6. Sheet lamination
Sheet lamination is a technology that operates by overlaying layers of materials (metal) in foils. Once the first foil is placed, a laser cuts it to the desired shape, the unwanted material is removed and a new layer is positioned. This is again shaped by a laser cutting out the unwanted parts and the layer is welded, using ultrasounds (UAM – Ultrasound Additive Manufacturing), to the previous layer. Depending on the type of 3D printer used the new layer can be welded before being cut by the laser or afterward.
Research is ongoing to make sheet lamination more flexible, that is being able to include a variety of materials and embed pre-fabricated components, like sensors, in the sheet layering. Robots can be used to increase the flexibility in additive manufacturing.
One of the problem in using different materials in the layering is the need for different bonding (welding) procedures depending on the materials. As an example, paper layers are pre-coated with glue that is activated through heath and pressure, metal foils are welded using ultrasounds, polymer foils by using pressure.
This 3D technology is usually used to print prototypes since the resulting object is often too coarse to be a product.