What Is Additive Manufacturing? Understanding The Technology And Its Impact.

Additive manufacturing refers to a process that uses CAD-generated 3D models to fabricate physical 3D objects by building them one layer at a time to form the desired shapes. This technology allows you to make highly optimized parts that are prohibitively expensive, if not impossible, to make with other processes.

For manufacturers, AM typically refers to the industrial use of 3D printing for activities such as building tooling and fixtures, prototyping and design validation, and production of low-volume end-use parts.

Additive manufacturing and 3D printing

Within the industry, additive manufacturing and 3D printing are typically used interchangeably. Technically speaking, however, 3D printing is a subset of AM, which includes a few other non-3D printing methods of manufacturing. Additive manufacturing typically carries an industrial connotation, often referring to the larger-scale use of 3D printing for manufacturing operations.

This distinction is important to note as the industry includes many cheaper, smaller-scale 3D printers. These do not satisfy the same purpose: they are typically employed as gimmick factories for novelty items and are not designed to perform in actual high-value manufacturing applications.

3D Printed Tooling & Fixtures

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How does additive manufacturing work?

Additive manufacturing works by converting digital inputs — such as computer-aided design (CAD) or by taking a scan of the files of industrial parts — into tangible 3D objects.

• Software

Once a user has a digital CAD file for their part(s), they will export the design as a .STL (Standard Tessellation Language) file. STL is the global industry standard file type for 3D printing. An STL is a solid-body representation of a part that 3D printing software can parse and turn into printing instructions.

The user then imports the part design as an STL file into an additive manufacturing "slicer" software. The slicer software — according to the user's various part and print settings — then translates the STL file into a set of machine instructions for the 3D printer.

With APIs, 3D printing software can integrate with factory systems, such as ERP or MES systems, to streamline and automate operations.

• Hardware

The 3D printer then uses the machine's instructions to determine the patterns in which it extrudes filament material. The printhead is programmed to move across both horizontal (X-Y) and vertical (Z) axes, and deposit material across points across the XY and Z axes according to the 3D printing software's directions. The 3D printing process builds objects from the bottom up — each additional horizontal layer is then stacked atop the previous layer. Print jobs are finished after the completion of the uppermost layer.

• Materials

For plastic and composite 3D printers, additive manufacturing typically uses spools of filament. 3D printers heat the filament into a molten plastic that it can extrude through a very small nozzle for precise placement. After it completes each layer, the material dries and hardens, after which the next layer can be printed.

Additive manufacturing with metals works differently than 3D printing plastics. These 3D printing materials are typically presented as metal powder. This is necessary because of the high melting temperatures for metals. A 3D printer's extrusion system cannot survive prolonged contact with molten metal, making the extrusion of metals not feasible. Therefore to additively manufacture metals, parts must first be printed in powder form and then converted into a uniform, fully metal part through a high-energy process — such as lasering, or sintering in a furnace.

Additive manufacturing materials

Plastics. Widely used plastics range from budget-friendly prototyping materials to rubbery, flexible filaments and high-performance thermoplastics like ULTEM™ 9085 Filament. Plastic materials are typically packaged in filament spools. Widely used plastics in 3D printing include:

• Nylon is a flexible, durable plastic material with good resistance to impact and chemical exposure.
• PLA (Polylactic Acid) is a cost-effective thermoplastic often used for rapid prototyping.
• TPU (Thermoplastic Polyurethane) is a flexible, impact-resistant rubber-like material.
• ABS (Acrylonitrile Butadiene Styrene) is another economical material. While a little weaker than PLA, it is lighter and more durable.
• ULTEM™ 9085 Filament is a high-performance thermoplastic used for demanding applications that require very high durability, temperature resistance, and chemical resistivity.

Metals. AM metals typically come in powder form, either as loose powders or bound together with a binder material. Popular available materials include:

• 17-4PH stainless steel is a versatile, common metal used for a variety of industrial manufacturing applications.
• A2 and D2 tool steels are cold work tool steels that offer extremely high hardness after heat treatment.
• H13 tool steel is a hot work tool steel that maintains material properties at high temperatures.
• Copper is often used for thermal and electrical operations. It conducts heat and electricity better than traditional metals.
• Inconel is a superalloy based on nickel and chromium. Inconel is used for applications that require resistance to corrosion, high temperatures, and chemicals.

Composites. Some FDM printers can create composite materials combining plastics with reinforcing fibers to improve the parts' strength, durability, stiffness, and heat resistance. Widely used fiber materials combined with plastics to form composites include:

• Carbon fiber is ideal for high-strength applications, with a 50% better strength-to-weight ratio than 6061 aluminum, a tensile modulus roughly equivalent to aluminum, and stiffness 24 times higher than ABS. Flame retardant carbon fiber varieties are often used in the aerospace, automotive, and transportation industries.
• Kevlar® Aramid Fiber is ideal for applications that require extreme durability, shock resistance, and impact resistance.
• Fiberglass is a cost-friendly all-purpose fiber that is three times stronger and 11 times stiffer than ABS.
• HSHT (High strength, high temperature) fiberglass maintains its properties at extremely high temperatures compared to other fibers — even up to 200°C.

For more information about continuous fibers and their role in 3D printing composites, read this article.

How organizations use AM across industries

Today, leading organizations across a wide range of industries incorporate additive manufacturing to address specific manufacturing needs:

• Aerospace. Major aircraft OEMs use additive manufacturing in their operations. AM allows them to streamline their supply chains by printing strong, lightweight end-use parts for aircraft, as well as print tooling quickly and economically.
• Consumer products. Additive manufacturing is used increasingly for end-use production parts on products such as audio equipment and electronic devices.
• Dental. Dentists and orthodontists use additive manufacturing to fabricate dental models, dentures, retainers, aligners, dentures, and more.
• Education. Leading universities are implementing additive manufacturing — in labs, maker spaces, and as part of engineering curricula — to educate the next generation of scientists, engineers, and manufacturers.
• Energy. Leading energy providers 3D print parts that make the manufacture and maintenance of wind turbines faster, easier, and more efficient than ever.
• Federal and Defense. Federal government organizations, such as the U.S. Air Force and Army, use additive manufacturing to accelerate R&D and solve supply chain issues with the ability to print mission-critical end-use parts from remote locations.
• Industrial Equipment. Industrial manufacturers use additive manufacturing to build custom tooling, accelerate go-to-market timelines, and print end-use parts for various types of factory machine systems.
• Medical. To meet production needs through strained supply chains, manufacturers of medical devices and equipment are 3D printing everything from tourniquet clips to COVID-19 personal protective equipment.
• Scientific and Laboratory. Scientific manufacturers 3D print end-use parts for various laboratory automation systems.