printing method, materials, how to choose

The advent of 3D printers opened a new era of technology — now it has become possible to print a three-dimensional object. The purpose of the resulting three-dimensional products can be very different — from toys to medical prostheses. The work is based on digital model (or drawing), which is then embodied in its exact real copy. Such devices are found in different capacities and configurations, in home and industrial versions. The types of 3D printers that exist today use a wide variety of materials to obtain three-dimensional printing.

3D Printing Technologies

With regard to the technologies used, a special classification is applied, which will be useful for every future owner of a 3D printer to know:

• FDM;
• Polyjet or MJM;
• LENS;
• LOM;
• SLA
• SLS;
• 3DP;

FDM

This is the most popular technology in the devices in question.. With FDM (fused deposition modeling), the unit will extrude the consumable through a special nozzle layer by layer. This includes:

• makerbot-like devices;
• Stratasys printers;
• aggregates used in cooking (cheese products, dough, icing are dressed);
• medical devices (medical gel with living cells).

Polyjet

MJM (Multi Jet Modeling) is also interesting, which implies a technique multi-jet simulation. The process is similar to conventional inkjet due to the supply of material through small nozzles (there may be several hundred of them). After solidification of the previous layer, the given three-dimensional model will be formed.

Consumables are photopolymers and plastic, special wax is also suitable. Usually such three-dimensional printing is used in the manufacture of medical implants, dentures and casts.

It is possible to obtain multicolor variants, as well as objects with different properties, for example, elastic in combination with hard ones.

There are also disadvantages of using this technology — a very expensive source material and fragile result. The application is usually found in medicine and industrial prototyping.

LENS

With LASER ENGINEERED NET SHAPING, the consumable blown out of the nozzle immediately falls under the focus of the laser beam, which is fraught with instant sintering. Usage metal powder helped in the manufacture of objects from steel and titanium, which made it possible to use 3D printers in industry. Many alloys can actually be mixed and obtained directly in the process. For example, turbine titanium blades for turbines are obtained.

LOM

With Laminated Object manufacturing, thin and already laminated sheets are laser cut, glued, sintered or pressed into a three-dimensional object. So you can print plastic, aluminum and paper 3D objects.

By the way, the source for aluminum objects is the corresponding foil — it will be «sintered» using ultrasonic vibration.

Despite the lightness of the starting material, paper models are very durable, and their cost will be almost a penny. But you must immediately prepare for the fact that such a product will be accompanied by a large amount of waste. Although the latter can be avoided if several small objects are placed on one sheet at once.

SLA

To understand how Stereolithography works, one must imagine a bathtub filled with liquid polymer. A laser beam passing through its surface polymerizes the layer. After one of the layers is ready, the platform will lower the part so that the liquid polymer fills the voids. Then the situation changes: the part rises up, and the laser itself is located below.

When working with this method, surface treatment is needed to sand and remove excess material. Sometimes the result is additionally baked in ultraviolet ovens.

Such a printer cannot be kept at home:

• due to the toxicity of the photopolymer;
• because of the cost of maintenance.

SLS

Selective laser sintering resembles the type of technology described above, but here instead of a photopolymer, a laser-baked powder is used. You can not be afraid of breakage during the operation of the part, and it is quite likely to use steel, nylon, bronze, titanium, ceramics, glass, casting wax and other materials as consumables.

Technology means creating complex things. It is great, for example, for creating any kind of prototypes — for example, for jewelry. The unbaked powder will serve as support for the overhanging elements, which means that no special support cases need to be formed.

3DP

The 3DP method consists in applying glue to the material, followed by a layer of fresh powder, and then all over again. The result is a gypsum-like material (sandstone). If you add paint to this glue, you will get colored objects. The technology is safe for domestic and office use. For materials, glass, bone, rubber, and even powders consisting of sawdust are suitable. Can be done and edible figurines (using chocolate or sugar powders) — only in this case a special food glue is taken.

Not without drawbacks — the end result can have a rough surface and low resolution.

Classification of printers by type of materials used

The consumable refilled into the equipment determines the types of 3d printers. Laser aggregates sinter and laminate the powder. Jet The 3D printer alternately glues the layers of the source material used, then it is sintered. The next step is cooling. Here, types of photopolymer plastic, resins, powders, silicone, metal and wax components can be used. Consider how this technique works on different materials.

Powder

The principle of operation of the technique is manifested in the following actions:

• based on the provided model, the print head starts applying a special binder to certain places;
• powder will be applied to it with a thin roller, which is sintered with the substance.
• then the process is repeated.

Such a device is quite real assemble with your own hands — it is enough to have the necessary accessories. Another bonus «in the piggy bank» of such an apparatus is working with metal powder.

Gypsum

The gypsum version is also filled with powders, but already appropriate — from gypsum to putty, cement and the like. Availability required binder. Such printers are most often used in the creation of interior decorations. Products here are very diverse.

photopolymer

For the manufacture of objects in this case, liquid photopolymers are used. An interesting principle creating figurines. Focusing on a computer model, the ultraviolet laser will illuminate certain places. In the future, they will harden under the influence of ultraviolet radiation. Such illumination will also be carried out through a specially prepared photomask — only here an ultraviolet lamp will be used. The template blank will change with each new layer.

If the technique chosen is stereolithographic, then you can enjoy the high precision of 3D printing. The only negative is the low speed of work, but if accuracy is a relevant indicator, then they do not pay attention to the execution time.

Wax

A similar device prints with wax, a material with a low melting temperature. This property has its own bonus — ease of work. That is why the clarity and precision of the contours made is impeccable.

How to achieve color

To make objects of a wide variety of colors, a special head is used in the technique. Here there are several extruders – components capable of melting and applying the consumable used.

Most of these units are involved in the manufacture of children’s toys. Another purpose is the creation of designer jewelry.

There is another way calledsublimation«. This type of printer is used if it is necessary to transfer an image (for example, from a photo) onto a relief surface. To implement the plan, dyes are heated in certain places — due to the temperature effect, evaporation occurs, and the desired pattern remains.

How to choose a 3D printer

When choosing a printer, first of all, you need to decide on what technology the printing is based on. An amateur-level device, but only this one can potentially be bought by an average consumer, and not a whole enterprise, work on the basis of a development called Plastic Jet (PJP), in some sources it is referred to as Fused Deposition Modeling (FDM) or Fused Filament Fabrication (FFF). Essentially, they are one and the same.

Types of materials for amateur printing

Basically, for printing on devices of this type, plastic with different characteristics is used. It is packaged in the form of a plastic cord wound on a reel or cut into strips. Two types of plastic are widely used: ABS and PLA.

ABS plastic safe, non-toxic, suitable for children’s products, moreover, it can be handled in the presence of children. Products made from it are durable and last a long time. The disadvantage of plastic is that it loses its presentation in the sun and in severe frost. It is more often used in professional manufacturing of parts.

PLA plastic (polylactide) is more brittle, does not serve as well. But it is more plastic and gives more opportunities for complex shapes. It is a natural product, as it is made from corn and sugar cane. In recycling, it is environmentally friendly, 100% decomposes into safe components. Products made of PLA are resistant to abrasion and keep their geometry. Hence, plastic is great for moving elements. In general, this is more of an amateur version of plastic.

Alternative materials for 3D printing

In addition to plastic, the following materials are used to work on such printers.

1. Stainless steel. Used only in professional equipment. Gives great opportunities for the manufacture of parts.
2. Wood. In fact, not a tree, but a mixture of a binding polymer with a wood additive. This material is very expensive, it does not require special skills to work. Products from it are “warm”, outwardly indistinguishable from wood.
3. Resin is also expensive. From it you can print high precision parts, with excellent surface quality — smooth and durable. Under the action of the sun, the resin loses its transparency.
4. Nylon. It is mainly used for the manufacture of elements for industrial and medical purposes.

Important! When buying print media, please note that the spool size and cord thickness must match the printer’s performance specifications.

Characteristics of 3D printers

To select a printer or conduct an analysis to identify a leader, you need to understand which device characteristics are key.

1. Print area. This parameter determines the maximum amount of parts that can be created using this equipment. The documentation indicates either the volume in cc or the maximum linear dimensions in mm.
2. Print resolution (layer). This is the thickness of the layer with which the material is applied. The higher the resolution, the thinner the plastic is applied, the reliefs are calm, the surface is of high quality. Below this value — the details come out more «clumsy», without fine workmanship. In some devices, this parameter can be set by the operator.
3. extruder. This is the working unit of the printer, which is responsible for preparing (warming up) and issuing material. Plastic (or other raw material) is softened by high temperatures in the nozzle and fed to the press (extruded). The composition of this assembly includes the nozzle itself, the conveyor for the cord (filaments of plastic), the temperature controller and the cooling mechanism. 3D printers with one extruder per pass can only work with one filament. To be able to multi-color sadness, the device must have at least 2-3 extruders. In industrial devices, the option of a single node with a double nozzle is possible. It’s expensive, and home appliances aren’t equipped that way.
   

   3D printer with two extruders

4. Printers can «connect» to external devices (computer, smartphone or just external memory) via USB and/or Wi-Fi. This is not always a prerequisite for work.
5. Printer firmware (software). It is preinstalled by default. His responsibilities include recognition, processing of documents in stl format for subsequent printing. These files are created in professional programs like Sketchup and Autodesk Inventors Fusion.
6. Additional functions. Ergonomics, design and other details do not interfere with the working processes in the printer, but often determine its cost.

3D printers can be supplied as an independent device (Assembled) or in a constructor format when the user assembles it himself (DIY). The second option costs much less.

Summarizing what has been said

3D printing attracts a large number of people who are interested in it out of personal curiosity or for industrial purposes. For those who do not have any experience in this field, it will not be difficult to learn the art of 3D printing, both in virtual and real courses. Another thing will be more important: for what specific purposes it is planned to buy such a device. Proper prioritization, combined with knowledge of the technology used for a particular application, will allow you to use the technique to one hundred percent.