Table 2.

Classifications of AM techniques.

Method	Various technology	Advantages	Limitations	Fabricated components	Ref
Directed Energy deposition	•Laser engineered net shaping •Electron beam direct melting •Rapid plasma deposition •Direct light fabrication •3D laser cladding	•Ability to control the grain structures •Production of relatively large parts with minimal tooling •repair of high-quality functional parts	•Surface finishing is dependent on the material used •Post-processing finishing is needed to achieve the desired effect	•Polymers •Metals •Composites	[102, 103]
Binder jetting	•Ink jetting •3D printing •Color jet printing	•Ease of building parts in multiple materials •Relatively low cost of fabrication •High speed •Allows the combination of powder materials and additives binders	•Poor accuracy and surface finish •Infiltration steps are required to achieve good mechanical properties	•Metals •Ceramics	[104, 105]
Powder bed fusion	•Selective laser melting •Direct metal laser sintering •Selective laser sintering	•Improved production development time •Efficient for reduced volume production and rapid prototypingEfficient recycling of un-melted powder	•Requires post-processing •Longer print time and relatively low speed of production	•Ceramics •Glass •Plastic •Metals	[106, 107]
Vat polymerization	•Digital light processing technology •Stereolithography	•High level of accuracy and excellent surface finish •It is relatively fast •Has large build areas	•It can only be used for photo-resin materials •After print, components are affected by ultraviolet rays •Longer processing time.	•Polymer •Ceramics	[108, 109, 110]
Material jetting	•Thermojet •Polyject	•Parts are useful for the design of casting pattern •Excellent accuracy and surface finishes	•Fragile parts owing to wax-like materials •Relatively slow build process	•Photopolymer •Ceramics	[110, 111]
Sheet lamination	•Ultrasonic AM •Laminated object manufacturing	•Ease of material handling •Support structures are not required •Relatively cost-efficient	•More waste is generated in comparison to other AM techniques •It has limited material options •Not suitable for the fabrication of hollow parts	•Metals •Ceramics	[112, 113]