What is Additive Manufacturing?

Additive Manufacturing is the identifying name of a whole series of manufacturing techniques and technologies in which the finished product is formed without the need to melt the material in molds or to remove it from a raw form.

Compared to traditional, typically subtractive techniques, Additive Manufacturing’s key feature enables enormous potential and flexibility in the most varied fields of application, from aerospace to biomedical.

Additive Manufacturing allows great freedom in the design and prototyping phases, extending the range of geometries and complexities that can be achieved indefinitely. It removes design and processing constraints.

The material is, in fact, added point by point and layer by layer, by the original model, similar to what happens for the digital printing of a document. From this analogy derives the now popular meaning of 3D printing, through which the media usually identify additive Manufacturing.

However, 3D printing as an audience catchphrase is bringing innovation both in production processes on a commercial scale. This is surely very welcome by all the actors involved.

The Official Standard Terminology for Additive Manufacturing

The regulatory bodies of various countries have jointly published a worldwide validity standard: ISO / ASTM52921–1 “Standard Terminology for Additive Manufacturing – Coordinate Systems and Test Methodologies.”

According to this document, additive technologies are defined as those processes that aggregate materials to create objects starting from their three-dimensional mathematical models, layer by layer. Additive Manufacturing proceeds in the opposite way to what happens in traditional subtractive processes with the removal of excess material. Additive technologies occupy a complementary role to that of the traditional ones.

The term 3D printing is often used as a synonym by the media, marketing department, and DIY enthusiasts. Also, it is easier for business people to grasp the concept as a process that creates products through the deposition of material employing a print head.

Additive manufacturing technologies produce physical models, prototypes, and components, using polymers, metals, ceramics, and composite materials, including biological tissues and food compounds.

Differences between additives manufacturing and numerically controlled production (CNC)

The additive process differs from the subtractive process of numerical control technologies. Additive Manufacturing overlaps a large number of techniques and even equipment with CNC machine technology. The true meaning of Additive Manufacturing exceeds the numerical control traditional procedures and scope.

However, the common procedure resulting from the use of CNC technology is starting from a solid to be emptied or carved. On the opposite, additive technologies build layer upon layer following a geometry of patterns with full and empty spaces.

The input is the vectorial 3D model of the object (CAD design), followed by the conversion of the file into STL format, which provides for the decomposition of the object into 3D-printable layers.

Finally, after the printing, the post-production process is often necessary to obtain adequate finishing levels and mechanical properties of the manufactured article, depending on the purpose of use.

One of the peculiar elements of all 3D printing technologies is the possibility of creating, in a unique printing process, objects that are traditionally made by many different individual parts.

Robotic Additive Manufacturing – RAM

Robotic Additive Manufacturing is the additive manufacturing technology based on the use of additive systems linked to robots. The new production process, according to industry experts, should soon revolutionize the concept of factory and metal implants. Companies who utilizes advanced techniques for Additive Manufacturing with metals are employing robots that can print metals at a very high-temperature.

Additive Manufacturing: How It Works

The additive process in the production phase is distinguished by a printing cycle that is repeated until the complete realization of a physical model.

With regards to additive manufacturing processes, however, the 3D printing part is only one of the moments that characterize a much more articulated workflow that can be divided into four fundamental phases.

1. 3d design cad: the vector project

Starting from the idea, we move on to the vector drawing phase using CAD (Computer Aided Drafting) software.

The computer design is the 3D design phase in which the geometries and parameters of the model to be created are established.

The file resulting from the 3D modeling (in .STL format), will be processed with the pre-press software through which the vector model will be converted into machine language.

2. Pre-press phase: surface control, supports, orientation and slicing

The phase preceding the 3D printing is of equal importance to that of the vector design.

The correct implementation of a 3D model with additive technologies, in fact, passes both through the CAD design to the computer. Through the surface analysis, the study of the print media and a correct table setting (positioning and orientation of the geometry within the print volume). During this phase, very important parameters concerning the consumption of materials and printing times are determined.

3. Setting the parameters of the additive device

The last phase, before the productive one, concerns the sending of the files to the machine and the choice of the printing parameters that will determine the realization times and the resolution level of the physical model.

A good deal of experience, the knowledge of the materials, and the 3D printing technology that you will use will be fundamental elements for the correct realization of your physical model.

The processes that lead from design to the finished model require control and, therefore, knowledge.

4. Additive manufacturing: 3D printing phase

The 3D printing phase is the least demanding, both physically and mentally.

Unlike what happened during the design and pre-press phase, you will only have to wait or dedicate yourself to other projects. The 3D printer will perform the assigned job for you and it will send you a warning message when printing is complete.

Just remember to check the level of materials before printing begins. Not all 3d printers allow a refill of materials during the realization process.

Additive manufacturing: post-process

The phase that follows 3D printing (not always necessary), usually involves threeprocesses :

Removing print media

In the case of 3D printing with polymers, the removal of printing media can be done by manual action using pliers, mechanical or manual abrasion, high-temperature furnaces for liquefaction of the supports, ultrasound systems.

In case you are dealing with parts made of metallic additives, it may be necessary to use precise cutting systems or mechanical abrasion systems.

Geometry stabilization

This type of process is used both for the printing of polymers and for the 3D printing of metals.

The stabilization of the photosensitive resins usually takes place inside an industrial oven with UV light.

In the case of additive manufacturing with metals, instead, the models are processed in high-temperature furnaces.

Surface finish

Surface finishing processes are adopted both for models made of metallic additives and for objects molded with polymers.

The finishing step can be carried out to make functional or aesthetic improvements and involves multiple processes such as polishing or sandblasting.

Thanks to engineering.com
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