How to choose 3D printing technology

How to choose 3D printing technology

This chapter is intended for those who are interested in printing three-dimensional models, either at home or professionally, and considering which printing technology to choose. We will detail the considerations that must be made before selecting the desired printing technology.

Preface

To begin a production process using 3D printing, there are a number of criteria and considerations that must be taken before printing begins. First, in order to choose a printing technology one has to refine the need for which the printing is intended. The different needs influence the choice of printing technology.

Needs for 3D printing

The needs can be classified according to a variety of criteria:

The importance of product visibility compared to its mechanical strength

There are printers that combine the two capabilities optimally and enable the production of models with mechanical strength suitable for industrial use, along with a high-quality final finish. But the price component of printing is also a consideration, the printer’s features and limitations, the printing material and unique options that exist in certain printing technologies (for example color printing). Visible models – models designed to show the aesthetic aspect of the product, for architectural models, sculptures, first visible models of products, etc. Typically, visible models require technology that will allow for low layer thickness, high resolution, and sometimes even color printing. On the other hand, the importance of mechanical reliability and structural strength of the parts in this case decreases. Functional models – models designed to demonstrate the feasibility of an idea or action of a mechanism. Models of this type can be used with lower resolution printers, but the mechanical strength of the components must mimic the strength of the final product in order to test its function as an active product. Finished components or products – Products that are intended for direct use in industry. These products usually require a printer that combines the ability to produce a product with mechanical reliability, strength and durability, along with a good final finish and high print resolution. According to the technologies that enable their production .

The material needed

There is a wide variety of materials that can be used in 3D printing. The properties required for the product must be assessed and on the basis of these, a material that allows their existence to be chosen. Example: strength, flexibility, transparency, heat resistance, etc. When the desired material is known, the choice of printer will be made according to the technologies that allow printing in the desired material. Sometimes there is more than one printer that allows printing on a particular material. In such cases the choice will be made both by the price of the print and by the features of the printer. Go to the article on various media

Desired printer features

Before selecting the technology, the desired printer features must be set. The printers differ in several features: Resolution – Layer thickness and print resolution affect the model finish and fidelity to a designed file . Tray Size – Print tray sizes vary from printer to printer. When the print tray of the desired printer is too small for the model, the model can be split into several parts and connected after printing. In addition, using a print tray that is too large for a small model can be time consuming and consequently unnecessarily costly. Time – Different printers have different print speeds. Occasionally, additional cooling / heating time is required after printing. Printing time is a consideration that must be taken into account when choosing printing technology, both for price and schedule reasons. Post-processing – Post-processing can be divided into two types: Essential Processing : Perform a binding process without which the product will not have its final properties in terms of mechanical strength or visibility. For example, additional hardening, cooling, or removal of support material.

Non-essential processing : Processes that can be done at the end of printing to meet product requirements. For example sanding or painting.

Classification of existing material properties according to the technologies used

As stated, before choosing the printing process, it is important to define what the visible and mechanical requirements of the product are. There is a wide range of properties that can be obtained through 3D printing. Below is an overview of the key features required in the production of various products.

Visible characteristic

Using Multiple Printing Materials :

technological material jetting
based on injecting material that has difficulty exposure to the beam UV, allows the use of several materials with different properties in one print (flexibility, transparency, hardness, etc.).

Colors
While some printing technologies allow monochromatic printing in color material (ie a model that is all in one color), there are two technologies that allow printing of color models that combine multiple colors in one print:
binder jetting – based on the injection of a crystallizing material into a powder, for example gypsum.
and the other material jetting

Transparency

There are two printing technologies that allow printing of transparent models.

The one material jetting This technology enables transparent models and uses water-soluble removable supports When printing is complete.

and the other SLA \ DLP a certain. These technologies require the use of supports and need to be removed with a smiley or nail file tool and their launch points processed into a model at the end of printing.

Smooth finish

Can be produced using SLA / DLP and using material jetting

A texture that mimics a certain material / has similar properties

Technology FDM – Allows the use of a filament (print material) that contains a high concentration of specific material chips, thereby giving The model has properties similar to the material it contains. You can create a look that resembles wood or metal with the help of appropriate filaments. In addition, this technology can be used to produce high-flexibility models with rubber-like properties.

Models with rubber-like looks and features can also be produced with material jetting or SLA / DLP But these technologies allow for less flexible manufacturing.
Mechanical properties

Flexibility

Flexible models can be created using a number of technologies:

FDM
Enables the production of models with high tensile capacity, supports are needed.

SLS
technology based on a material powder sinter. Allows production of models with high tensile capacity without the need for supports.

SLA / DLP
Enables the production of flexible models but not high tensile capacity. Supporters are needed.

Material jetting

Allows you to create models that are flexible, but do not have high tensile capacity. No support needed.
Strength

The strength of the printed products differs according to the type of printed material. Some printers allow printing in metal
(DMLS, SLM, binder jetting ) and allow the creation of extremely powerful models suitable for use in various industries. Strong models can also be made of plastic (for example in technology > SLS ).

Heat / Fire Resistance

Heat-resistant models can be produced using a number of technologies:


SLA / DLP

SLS

Biocompatibility (Biocompatibility) or Edible Adaptation

Models that are biocompatible or edible compatible can be produced using the following technologies:

DMLS / SLM – Technologies used to create metal models by melting or close to melting a powder using a laser. (Extension on the subject
SLM Chapter 5)

FDM

SLA / DLP

Print Materials

The media can be divided into several main groups: metals, polymers (plastics) And ceramic materials. Later in this chapter we will focus on each of these groups, their properties and uses.

There are several configurations for different media: powder, coil of material and a thick liquid called resin, and they vary depending on the printing technology.

Polymers (Plastics)
Thermostatic materials

The polymers are divided into two groups: thermoplastic and thermostatic. The difference between the two lies in the ability of the materials to switch to a solid aggregation state and back to a liquid. While solid thermoplastic materials can be melted and can be repeatedly melted even after cooling and solidifying, thermostats can become solids in a one-time process only and when exposed to certain temperatures they decompose and burn.

These materials are suitable for visible models where aesthetics and product visibility are of main importance. You can produce a smooth surface finish with them, and even get special features such as flexibility or suitability for medical uses. In contrast, they are less suitable for functional use as they are fragile and brittle.

Thermostatic materials have two possible states of aggregation, liquid and solid. As stated earlier, these materials can switch to a solid aggregation state in a one-time process that does not allow them to return to the previous liquid aggregation state.

The transformation of thermostatic materials into solids can be caused by a number of factors that vary from material to material. Some materials harden when exposed to heat and some when exposed to a certain length or wave type.
There are thermostats that have difficulty when exposed to certain light rays, usually UV rays. These materials are called photopolymeric materials.

The printing technologies that use photopolymers to create solid models are SLA, DLP , and material injection ( Material Jetting ). While SLA and DLP produce a less smooth finish as they require the use of supports, material injection allows the creation of models with a smoother finish using soluble supports. However, material injection technology is more expensive.

Thermoplastic materials

These materials are suitable for the production of functional products that can be used directly in industry. They can be used to produce products with high mechanical reliability and structural strength, and some are suitable for food products and skin contact. The final product can be recycled and is safe to use. On the other hand, it is not possible to produce transparent products, and in some technologies the surface is less smooth.

The printing technologies that use thermoplate materials are FDM MJF and SLS.
In FDM technology, the thermoplastic material arrives in a solid aggregation state in the form of a material coil. The coil passes through a small, heated tube in a process called extrusion, and with the help of the molten coil the three-dimensional model is constructed. In this technology, the product is not smooth and the print layers can be seen. In addition, the technology uses supports that leave a mark on the printed product.

In SLS and MJF technologies the material comes as a plastic powder that undergoes a process of sintering or melting. This process causes the plastic granules to come together into one solid model. There is no need for supporters in this technology.

Metal

Metal-printed products have structural strength, resistance to extreme heat conditions and suitability for use in industry as functional products. Today, the engineering and medical industries use metal printers for the manufacture of lightweight products relative to products made by traditional manufacturing methods.

The printing technologies that use metals are DMLS, SLM and Binder Jetting .
DMLS and SLM technologies enable the production of models with higher resolution and higher mechanical reliability. Binder Jetting technology enables the production of models at a cheaper cost and on a larger scale.

Ceramic materials

Printing with ceramic materials allows the creation of visible and even colored patterns if necessary. These materials are very fragile if they are not subjected to a deliberate reinforcement process after printing. Therefore, they are generally not suitable for functional uses in industry, but are used for the production of aesthetic models, such as architectural models.
The printer using ceramic materials belongs to the Binder Jetting .

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