SLM or Selective laser melting - innovative technology production of complex products by laser melting of metal powder according to mathematical CAD models (3D metal printing). With the help of SLM, both precise metal parts are created for work as part of units and assemblies, as well as non-separable structures that change geometry during operation.

The technology is an additive manufacturing method and uses powerful lasers to create three-dimensional physical objects. This process successfully replaces traditional production methods, since the physical mechanical properties Products built using SLM technology often surpass the properties of products made using traditional technologies.

SLM machines help solve complex production challenges industrial enterprises working in the aerospace, energy, machine-building and instrument-making industries. The installations are also used in universities, design bureaus are used in research and experimental work.

The official term for describing the technology is "laser sintering", although it is somewhat untrue, since materials (powders) are not sintered, but melted to form a homogeneous (thick, pasty) mass.

Advantages

1. Solving complex technological problems

• Manufacture of products with complex geometry, with internal cavities and conformal cooling channels

Shortening the R&D cycle

• The ability to build complex products without the manufacture of expensive tooling

Weight reduction

• Construction of products with internal cavities

Material savings in production

• The construction takes place by layer-by-layer addition of the required amount of material to the “body” of the product. 97-99% of the powder not used in the construction after sieving is recyclable. 3-9% of the material involved in the construction of supports is disposed of along with substandard unfused powder that has not passed the sifting operation.
• Reduction of costs for the production of complex products, tk. there is no need to manufacture expensive equipment.

Areas of use

• Production of functional parts for work as part of various units and assemblies
• Manufacture of complex structures, including non-separable ones that change geometry during operation, as well as having many elements in their composition
• Production of shaping elements of molds for injection molding of thermoplastics and light materials
• Production of technical prototypes for testing the design of products
• Creation of forming inserts for chill casting
• Production of individual dental prostheses and implants
• Making stamps.

How it works

The printing process begins with dividing the 3D digital model of the product into layers 20 to 100 microns thick to create a 2D image of each layer of the product. The industry standard format is the STL file. This file enters a special machine software, where the information is analyzed and compared with the technical capabilities of the machine.

Based on the received data, a production cycle of construction is launched, consisting of many cycles of building individual layers of the product.

The layer construction cycle consists of typical operations:

1. applying a layer of powder of a predetermined thickness (20-100 µm) on a build plate fixed on a heated build platform;
2. laser beam scanning of the section of the layer of the product;
3. lowering the platform deep into the construction well by an amount corresponding to the thickness of the construction layer.

The process of building products takes place in the chamber of the SLM machine, filled with an inert gas argon or nitrogen (depending on the type of powder from which the construction is made), with its laminar flow. The main consumption of inert gas occurs at the beginning of work, when the build chamber is purged, when air is completely removed from it (permissible oxygen content is less than 0.15%).

After construction, the product, together with the slab, is removed from the chamber of the SLM machine, after which the product is separated from the slab mechanically. Supports are removed from the built product, and the finished product is finished.

The almost complete absence of oxygen avoids the oxidation of the consumable, which makes printing possible with materials such as titanium.

materials

The most popular materials are powdered metals and alloys, including stainless steel, tool steel, cobalt-chromium alloys, titanium alloys, titanium, aluminum, gold, platinum, etc.

Products made by SLM Solutions 3D machines

Products made by Realizer 3D machines

Video: using SLM technology

SLM technology - layer-by-layer laser melting of metal powders - is one of the methods of additive manufacturing of products, which has been actively gaining momentum over the past 10 years. Today it is already quite well known to production workers. This technology has an abyss of advantages, but, nevertheless, when operating equipment based on it, it does not cease to amaze with new opportunities. The leader in the production of equipment for this technology is the German company SLM Solutions.

Since recently, it has been represented in Ukraine by Stan-Komplekt JV.

Selective laser melting (SLM) technology is a powerful manufacturing solution for businesses that need fast and quality manufacturing products from various metals.

SLM installations are now actively used in the most different areas industry for the production of master models, mold inserts, prototype parts, finished products from stainless and tool steel with the presence of cobalt, chromium and nickel, as well as from aluminum, titanium, etc.

SLM Solutions is the founder of SLM technology (patents since 1998) and one of the world leaders in the production of equipment based on it.

The company's headquarters and production facilities are located in Lübeck (Germany).

SLM technology

SLM technology is an advanced method for the production of metal products by layer-by-layer laser melting of metal powder based on 3D computer design data. Thus, the production time of the product is significantly reduced, since the need for many intermediate operations disappears. The process is the successive melting of the thinnest layers of metal powder using modern fiber lasers, thus building up the detail layer by layer. This technology creates precise and homogeneous metal products. Using the widest range of quality powder metals and alloys, SLM technology offers unprecedented opportunities for the production of industrial metal parts with significant advantages: shape complexity, minimal wall thickness, combination of materials of different densities, no post-processing, no waste, cost-effectiveness, etc. Software, supplied with the units, has an open architecture, which also expands the capabilities of this equipment.

The principle of operation of SLM installations:

• for preliminary data processing in the CAD system, cross sections of a 3D model with a minimum step are obtained;
• the powder is fed from the automatic device to the heated working platform, then it is distributed on the plane with the thinnest layer in two directions;
• modern glass fiber lasers melt a segment of each layer according to the configuration of the cross section of the part in given coordinates (2D file).

In this case, each subsequent layer is welded onto the previous one, which ensures the uniformity of the product structure.

This procedure is repeated until the resulting product exactly matches the CAD model. Unmelted metal powder is removed into a special chamber, after which it is reused.

Benefits of SLM installations

SLM Solutions' line of laser sintering equipment utilizes a number of unique, patent-protected components and technologies:

MULTILASER— simultaneous use of two or more (up to 4) lasers.

Allows you to achieve a productivity increase of 400% compared to machines equipped with a single laser;

UNIQUE DOUBLE BEAM TECHNOLOGY(Hull Core). The use of two different lasers (400 and 1000 W) allows for even faster and better sintering. Where maximum accuracy is required, the installation uses a thinner laser beam, and to increase speed in simple areas, its power and diameter increase;

POWDER DISTRIBUTION IN TWO DIRECTIONS IMMEDIATELY. The innovative SLM Solutions allows you to cut the print time of the product in half;

LARGE CAMERA DIMENSIONSlarge chamber sizes. Laser sintering plants are designed to produce parts up to 500 × 280 × 365 mm in size (data as of July 2016). In one session, you can grow one large product or several small ones;

HIGH SPEED AND PRECISION OF MANUFACTURING: SLM Solutions equipment is capable of producing up to 105 cm3 of finished metal products per hour. This is 1.5-2 times more than units of this class from other manufacturers. The minimum wall thickness is only 180 microns. Along with this, tracking systems for the construction process and quality control provide a high degree of control over the entire production cycle;

WIDE SELECTION OF MATERIALS: stainless steel, tool steel, nickel-based alloys, aluminium, titanium. The most reliable, proven and versatile materials. Thanks to the open software architecture, metal powder from any manufacturer can be used, without additional reconfiguration costs;

SPECIAL SOFTWARE. SLM Solutions laser melting machines are supplied complete with special software - SLM AutoFabMC. It not only simplifies the 3D printing process, but also allows you to optimize production processes, reduce build time and save Consumables. The software allows you to work with the most widely used data formats in the production environment.

Main consumers

Aerospace

print

Details & Materials

3D printing for industry: a detailed overview of the latest equipment and technologies

At the exhibition formnext traditionally gathers the elite from the world of additive technologies and 3D printing. World-class experts noted the transition from creating prototypes to manufacturing parts and blanks from metals and functional materials.

Classical SLM-, EBM- and DMD-technologies when working with metals supplemented relatively new CSF- and FDM-like technologies. A detailed overview of the equipment, materials and advanced solutions presented in Frankfurt am Main from expert Kirill Kazmirchuk.

selective laser melting(SLM - Selective Laser Melting)

A hybrid system that uses the SLM process and 3-axis CNC machining in the same machine.

This approach makes it possible to obtain metal parts with internal channels of low roughness.

Working area: 600 x 600 x 500 mm

Trumpf TruPrint 5000

SLM machine from a company that produces a wide range of laser equipment. Feature of TruPrint 5000 - replaceable working modules. They allow you to run a build without lengthy preparation. The “unpacking” of the building takes place outside the machine in a special “unpacking-cleaning” station.

Working area round: Ø300 x 400 mm

Materials: Al, Ti, Ni, Co-Cr, Steel.

SLM-Solutions SLM 800

The largest machine from the company - a pioneer in the SLM technology segment. In early 2017, the acquisition of SLM-Solutions by industry giant General Electric was announced. The transaction did not take place due to a disagreement of opinions on the value of the shares. As a result, GE acquired another company, Concept Laser.

Car SLM 800 was announced at formnext-2016 and presented to the public at the exhibition in 2017. Within the framework of the exhibition, according to SLM-Solutions itself, twenty units of this equipment were sold.

Working area: 280 x 500 x 800 mm

Materials: Al, Ti, Ni, Co-Cr, Steel.

Over 15 cars sold since the beginning of the year SLM 500, mainly to China.

Electro optical Systems M400-4

SLM machine with working area 400 x 400 x 400 mm

Materials: Al, Ti, Ni, Co-Cr, Steel.

Four lasers are used, each covering a quarter of the working area. This allows you to significantly reduce the time of building a large number of small parts, but when manufacturing one large part, the time is reduced by up to 10%. Potentially, due to a more uniform fusion process, thermal deformations are reduced.

Additive IndustriesMetalFab1

MetalFab1 is a set of equipment: SLM machine + cleaning station + heat treatment oven. Technologically, the transitions take place in an isolated space, respectively, the contact of the operator with metal powders is reduced.

Working area 420 x 420 x 400 mm

Materials: Al, Ti, Ni, Co-Cr, Steel.

concept Laser (company acquiredGeneral electric early 2017)

The car was presented Atlas with working area 1000 x 1000 x 1000 mm.

Shown is a prototype of this machine and a detail built on a 1000 x 1000 mm platform.

Materials: Al, Ti, Ni, Co-Cr, Steel.

The release date was not made public.

On this moment the current model is X- line 2000 with two lasers and working area 800 x 400 x 500 mm.

Orlas creator

ORlaser is known for several years of developing laser hot powder welding heads. Now the company's own SLM machine with a working area of ​​Ø 100 mm x 110 mm is also presented.

This is a small apparatus with a cylindrical working area. Additionally, it can be equipped with a spindle for CNC processing.

French company, developing with the active participation of tire manufacturer Michelin. The main products are SLM layer-by-layer synthesis machines.

The peculiarity of these plants is that they specialize in the use of finer metal powder (about 20 µm), while the typical particle size in similar equipment is 40-60 µm. Smaller particle size, on the one hand, gives best quality surface and the study of small details of geometry, on the other hand, imposes a significant limitation on the use of powder. Finer powder is more difficult to handle, requiring isolated rooms and operator protection.

Working area: 350 x 350 x 350 mm.

DMG MORI

The company is a manufacturer of CNC machines for turning, turning-milling and milling groups. For about five years, he has been promoting a hybrid technology for the manufacture of metal parts on the market: DMD surfacing + CNC machining. Hybrid technology in the automotive industry is suitable for the most part for repair tasks - restoration of crankshaft journals, camshaft cams.

In 2017, a self-developed SLM machine LASERTEC 30 SLM with a working area of ​​300 x 300 x 300 mm was shown.

The applicability of the technology for the manufacture of heat exchangers and small brackets with complex geometry is shown.

Portuguese company producing a wide range of equipment for metal processing (hydraulic bending machines, guillotine metal cutting, laser cutting, etc.). In additive manufacturing, the newcomer, however, has unveiled what they claim is the largest SLM machine with a working area of ​​1000 x 1000 x 500mm.

The machine uses only one laser, and a large area allows you to cover the principle of a movable build zone. The construction takes place on a platform measuring 1000 x 1000 mm, a square chamber with a radiation source and a local supply of inert gas moves above it. The construction process is step-by-step, and the metal is fused in the right places. Potentially, this approach involves a greater consumption of inert gas and limits the construction of large parts. At the moment, the process is debugged only for steels.

3 D Systems

In the company's lineup, the ProX 320 SLM machine with a working area of ​​275 x 275 x 420 mm is interesting.

An SLM machine was also announced DMP8500 with working area 500 x 500 x 500mm. The advantage of 3D Systems machines is the ability to work both with a standard powder of 40-60 microns, and with fine powder of the order of 20 microns.

EBM-technologies

Arcam Q20 Plus(purchasedGeneral electric at the beginning of 2017)

The only company is the manufacturer of EBM machines. The equipment is specialized for the use of titanium alloys. The use of an electron beam instead of a laser can significantly improve the quality of metal fusion and increase the speed.

Working area: Ø 350 x 380 mm.

Material: Ti6Al4V.

Cold gas dynamic surfacing (cold spray)

The essence of the technology lies in the application of powder particles using a supersonic jet of transport inert gas. Due to the high speed, the particles stick to the surface, providing a dense metal structure. Potentially, this approach makes it possible to build blanks in a shorter time than laser cladding, due to the lack of heating and subsequent cooling.

SPEE3D

The American company SPEE3D introduced in 2017 a hybrid machine that allows you to create metal blanks using cold gas dynamic surfacing followed by CNC machining.

Due to technological limitations, the technology is applicable to create blanks for subsequent CNC processing. The quality of the surface shown in the photo is comparable to casting.

Aluminum and copper alloys.

The German company - manufacturer of CNC machine tools introduced its own CSF + CNC hybrid equipment.

Parts are formed sequentially from several materials, and cold surfacing is used to create cooling channels and cavities inside the molds. A more fusible metal is applied to the required areas and acts as a removable support. Aluminum and copper alloys can be applied.

ImpactInnovations

Equipment for cold gas dynamic surfacing with material switching during the manufacturing process. Allows you to apply aluminum and copper alloys (including the surface of non-metals). The technology can be useful when creating bimetallic products (sliding bearings), as well as when applying conductive "paths" to textolite or other polymer products.

Hot hardfacing

The essence of the technology lies in the application of powder particles using a jet of transport and protective inert gas, the metal is melted when it comes into contact with a surface heated by a laser.

For the manufacture of parts, the technology is very limitedly suitable, mainly only for creating a case. More applicable to the repair of shafts and other bodies of revolution.

inssTek,BeAM respectively, Korean and French company. The equipment is built on a similar principle and has similar capabilities.

It is possible to "switch" the materials in the process of manufacturing blanks.

InssTek has a large working area and is 4000 x 1000 x 1000 mm.

Products require subsequent thermal and mechanical processing.

DMGMORI

Pioneer in hybrid (surfacing + CNC) technology for metal products. Was first released combined machine lasertec 65 3D, then lasertec 4300 3D joined the hybrid range.

Similar machines are manufactured today by Yamazaki Mazak.

CEFERTEC

The equipment was developed with the participation of the FIT AG service bureau and, to put it simply, is a CNC welding machine for metal.

Built on the basis of a portal and a turntable.

The technology allows you to quickly create blanks from metal. The approach raises many questions about the quality of products and properties, as well as the inevitable warping in a localized thermal process.

Metals and FDM technology

The principle of construction is the extrusion of a plastic material (filled with metal powder) through a die. After creating a polymer-metal model, it is sintered in an oven (thermal or microwave). At this stage, the polymer binder evaporates and the metal particles sinter. In this case, the shrinkage of the part is 18-20%, see the photo below. Software unconfirmed information, such technology potentially allows you to build parts up to 100 times faster.

DesktopMetal And Markforged- American companies, they use similar technology, the working area is 330 x 330 x 330 mm and 250 x 220 x 200 mm, respectively. It is worth noting a significant difference in the degree of readiness for deliveries. If DesktopMetal is not ready to supply equipment even to the local market, then Markforged is willing to supply both the US and Europe. A feature of all Markforged equipment is that the file is sent to the build when connected to the Internet and the company's servers, which raises the issue of maintaining trade secrets.

On the one hand, the FDM technology looks promising, since it makes it possible to obtain metal parts without the need to work with metal powders that are difficult to handle. On the other hand, many questions remain, such as the maximum wall thickness (may be limited due to the need to remove the binder), the absence of such equipment with a large working area, etc. The technology will certainly find its niche, but it cannot be considered as a "killer" or replacement for SLM technology.

X- Jet

An Israeli company, the main part of which is the employees of Objet, the pioneer of PolyJet technology.

An analogue of this technology is also used in the X-jet equipment: a water-based liquid binder is applied to the platform, in which metal or ceramic particles are distributed. The filler does not stick together and does not precipitate due to van der Waals forces.

Parts also require heat treatment (and possibly pressure) after the layer-by-layer synthesis process. The manufacturer does not specify the details of the technical process, and the samples of metal and ceramics shown at the exhibition do not exceed the size of a few centimeters, but the detailing is at a high level.

Working area 500 x 280 x 200 mm.

High strength PEEK thermoplastics

Group materials PEEK(polyetheretherketone) are very interesting for direct production due to their strength and heat resistance. Heat resistance up to 250 °C, and tensile strength 100 MPa (for comparison, for aluminum, depending on the alloy, it varies from 100 to 350 MPa). It is difficult to process such material because of the high melting point - above 340 °C. Three FDM machines for working with PEEK were presented at once: INNOVATOR 2 PEEK, INTAMSYS PEEK And GEWO 3D PEEK.

The largest machine has a working area of ​​450 x 450 x 600 mm and an extruder temperature of up to 450 °C.

Sand Printers for Foundry

VoxelJet

ExOne and Voxeljet were originally one unit and created equipment for working with sand and polymeric materials for foundry applications.

In 2003, the companies split, Voxeljet still develops both areas, while ExOne (formerly Prometal RCT) focused only on sand technology and partly on work with steel-bronze materials.

IN model range Voxeljet has several systems capable of working with sand to create molds and cores. All of them are similar in mechanics and process to ExOne equipment.

As part of formnext-2017, the company presented a system for working with functional polymeric materials. The technology is based on the already mastered PolyJet with a photosensitive binder, this not only makes it possible to achieve improved properties, but also allows you to create products more high definition. The technology is similar to the one shown by Hewlett Packard at the 2016 show.

A Korean company that has several industrial additive manufacturing machines in its lineup:

– sand PolyJet printer with a working area of ​​300 x 420 x 150 (inorganic binder, more environmentally friendly);

– sand SLS-printer with a working area of ​​600 x 400 x 400;

– SLM machine with a working area of ​​350 x 300 mm;

– hybrid machine (surfacing + CNC machining) with a working area of ​​250 x 250 x 250 mm.

Metal powders

The largest manufacturers of metal-powder compositions were widely represented at the exhibition: Haraeus,LPW,SMTChina,Oerlikon,EPMA And polema(Russia).

AtomizerATOone

Installation for the production of powder metal compositions for machines for layer-by-layer synthesis from the Polish company 3D lab.

This is an “office” atomizer no more than 2 meters high, the typical size of industrial atomizers is 5-10 m in height and about 4 m in diameter.

Wire is used as a material for processing, and the capacity of the equipment allows to produce up to 200 grams per day.

Polymer materials and equipment

Composites

Markforged

FDM-equipment is presented, which allows to work with thermoplastics filled with carbon, Kevlar and glass fibers. They can be both continuous and chopped.

The installation cost is about 100-1000 euros.

Photo from top to bottom:

– part made of Onyx material (chopped fiber);

- detail from the material Onyx (chopped fiber) in the section;

– reinforced with continuous Kevlar;

- reinforced with continuous fiberglass;

– reinforced with continuous carbon fiber.

Stratasys

The company introduced Nylon CF material compatible with the Russian Fortus 450mc FDM machine. It is a polyamide filled with chopped carbon fibers.

It provides better mechanical properties than standard unfilled materials. In the photo, a comparison of the behavior of materials under loading (on the right ABS, in the center Nylon CF, left Nylon 12).

Desktop SLAs and Stretch Materials

digitalwax And atum 3D

The working area of ​​the larger machine is 300 x 300 x 300 mm, photopolymer materials are available, both functional and elastic.

UNIZ SLA

The Chinese company UNIZ is a newcomer to the market. Two desktop SLA machines with work areas are presented: 315 x 185 x 450 and 192 x 122 x 200. The manufacturer claims that this is the fastest SLA machine. Experts have yet to figure out what kind of materials the system uses and what determines the speed of building 2500 cc. cm per hour (50% coverage).

Both systems use LED illumination of the photopolymer (LCD-Stereolithography).

Japanese company with a long history. Engaged in the production of a variety of high-precision equipment - from printers to microscopes. Introduced its own Agilista 3D printer using PolyJet technology. Emphasis is placed on the ability to produce flexible and heat-resistant silicone products. Such equipment can be useful in the manufacture of small series of grommets, door seals, air duct nozzles, etc.

Working area: 297 x 210 x 200 mm.

Materials: polymeric compositions based on silicone, including heat-resistant up to 100 °C.

Electro Optical Systems

SLS machine P500 from EOS - one of the market leaders. Working area 500 x 330 x 400mm, two 70W lasers for faster work, sintering temperatures up to 300°C and build speeds up to 6.6 liters per hour (20% faster than market peers).

The system is equipped with a changeable working zone with controlled cooling, which increases the percentage of loading and dimensional stability of products. SLS machine software allows you to connect to the system Enterprise ERP and track in real time the percentage of completion of the task.

Material: polyamide, developed by PEKK.

Polish SLS-machine, capable of working with powdered polyamide.

Working area: 350 x 350 x 600 mm.

Large SLA machines

RPS was founded in the UK by employees of DTM and 3D Systems and has been in existence for over a decade.

She began her activity with the maintenance and restoration of machines for layer-by-layer synthesis.

In 2016, a large SLA machine was released NEO 800 own development.

Working area: 800 x 800 x 600 mm.

Materials: photopolymer compositions from DSM Somos and any others.

Stereolithographic machine from a European company, made in China.

Working area: 700 x 700 x 450 mm.

Materials: photopolymer compositions from DSM Somos and any others, including their own from Raplas.

Ceramics

To work with ceramics, as a rule, SLA technology is used, these are companies Ceramaker And Lithoz.

In the classic SLA process, a blank is created, the so-called green model. After construction, it undergoes a heat treatment procedure, where the polymer component is removed and ceramic particles are sintered.

Services

In Europe, production sites are successfully developing, providing services for the manufacture of prototypes from polymers, composites and metals, using additive technologies.

The leading companies in this market are Poly Shape, Hoffmann, CitimGMBH, FITAG. The latter recently opened a branch in Russia.

In the arsenal of such companies, DMD, SLM, SLS, FDM, EBM equipment is widely represented, the number of employees in the additive direction, as a rule, is about 100-200 people. The companies are in demand on the market, below are the profitability indicators (revenue) for 2016: Hofmann GMBH - $833.2 million, CITIM GMBH - $27.3 million, FIT AG - $24 million.

It should be noted that in October 2017 the plant ACTech was acquired by Materialize, and will soon develop direct production of metal parts using additive technologies.

Tomography

VisiConsult And Werth- manufacturers of tomographs, presented their small devices for tomography of metal and polymer parts. The industry is beginning to think about product control. This is a sign that parts are increasingly being used as end products.

Software

SLM (Selective Laser Melting) - selective (selective) laser melting - an innovative technology for manufacturing complex in shape and structure products from metal powders using mathematical CAD models. This process consists in sequential layer-by-layer melting of the powder material by means of high-power laser radiation. SLM opens up front modern industries the widest possibilities, as it allows you to create metal products of high precision and density, optimize the design and reduce the weight of the parts produced.

Selective laser melting is one of the metal 3D printing technologies that can successfully complement classical manufacturing processes. It makes it possible to manufacture objects that surpass the products of standard technologies in terms of physical and mechanical properties. With the help of SLM technology, it is possible to create unique complex-shaped products without the use of machining and expensive equipment, in particular, thanks to the ability to control the properties of products.

SLM machines are designed to solve challenging tasks in energy, oil and gas, machine-building industries, in metalworking, medicine and. They are also used in scientific centers, design bureaus and educational institutions when conducting research and experimental work.

The term "laser sintering", which is often used to describe SLM, is not entirely accurate, since the metal powder supplied to the 3D printer under the laser beam does not sinter, but completely melts and turns into a homogeneous raw material.

Application examples of selective laser melting technology

Where SLM technology is used

Selective laser melting finds application in industry for the manufacture of:

• components of various units and assemblies;
• structures of complex shape and structure, including multi-element and non-separable;
• stamps;
• prototypes;
• jewelry;
• implants and prostheses in dentistry.

Data analysis and product building

First of all, the 3D digital model of the part is layered so that each layer, having a thickness of 20-100 microns, can be rendered in 2D. The specialized analyzes the data in the STL file (industry standard) and compares it with the specifications of the 3D printer. The next stage after processing the received information is construction, which consists of a large number of cycles for each layer of the created object.

Building a layer includes the following operations:

• metal powder is applied to the build plate, which is fixed on the build platform;
• the laser beam scans the section of the product layer;
• the platform is lowered into the construction well to a depth that matches the thickness of the layer.

The construction is carried out in the chamber of the SLM machine, which is filled with an inert gas (argon or nitrogen). The main volume of gas is consumed at the initial stage, when all air is removed from the build chamber by blowing. Upon completion of the construction process, the part, together with the plate, is removed from the powder 3D printer chamber, and then separated from the plate, the supports are removed and the final processing of the product is performed.

Benefits of Selective Laser Melting Technology

SLM technology has serious prospects for improving production efficiency in many industries, because:

• provides high accuracy and repeatability;
• the mechanical characteristics of products printed on this type of 3D printer are comparable to;
• solves complex technological problems associated with the manufacture of geometrically complex products;
• reduces the cycle of research and development work, ensuring the construction of complex-shaped parts without the use of tooling;
• allows you to reduce the mass by building objects with internal cavities;
• saves material in production.

SLM Solutions: integrated system solutions for metal 3D printing

Products created at the SLM Solutions facility

SLM Solutions, headquartered in Lübeck, Germany, is a leading developer of metal additive manufacturing technologies. The main activity of the company is the development, assembly and sale of equipment and integrated system solutions in the field of selective laser melting. iQB Technologies is the official distributor of SLM Solutions in Russia.

We continue to consider existing 3d printing technologies and their features. Next in line are the following 3d printing methods:

Direct Metal Laser Sintering (DMLS)

Instead of DMLS (Direct Metal Laser Sintering), you can also see the name SLM (Selective Laser Melting). This technology owes its second name to the German company EOS. The company is one of the leaders in layer-by-layer prototyping. We recently wrote about their latest development - microlaser sintering ().

The main consumers of the technology are the fields of medicine, microelectronic industry and partially.

When manufactured using DMLS technology, the products have an impressive layer thickness of 1 - 5 nm at maximum dimensions product details 60 mm in diameter and 30 mm in height.
The manufacturing process of the product is based on the flow of the melt-binder into the voids between the powder particles under the action of capillary forces. To improve the flow process, compounds with phosphorus are added to the powder mixture, thereby reducing the surface tension, viscosity and degree of oxidation of the melt. The binder powder particles are generally smaller in size than the base powder particles. This helps to increase the bulk density of the powder mixture and accelerate the process of melt formation.

To date, there are the following materials for 3d printing using DMLS technology:

• DirectMetal 20 (Bronze based metal powder)
• EOS StainlessSteel GP1 (Stainless steel, similar to European 1.4542)
• EOS MaragingSteel MS1 (Maraging Steel)
• EOS CobaltChrome MP1 (Cobalt-Chromium-Molybdenum Super Alloy)
• EOS CobaltChrome SP2
• EOS Titanium Ti64 / Ti64ELI (Titanium alloys)
• EOS NickelAlloy IN625 (Nickel Alloy)
• EOS NickelAlloy IN718 (Nickel Alloy)
• EOS Aluminum AlSi10Mg (Aluminum alloy)

Electron Beam Melting (EBM)

The method of electron beam melting originated within the walls of the aerospace industry. After that, he began to conquer the civil sphere as well. starting material metal powder is used in the production. Usually these are titanium alloys.

The production of the product is carried out as follows: the required amount of powder is poured into a vacuum chamber, then a controlled flow of electrons “bypasses” the contour of the model layer by layer and melts the powder in these places. This results in a strong structure. Due to the presence of vacuum and the overall high temperature, the final product obtains a strength similar to that of forged alloys.

Compared with DMLS and SLS technology, electron beam melting does not require subsequent heat treatment to obtain high strength. Also, this method is faster and more accurate due to the high energy density of the electron beam.

The leader in this field is the Swedish company Arcam.

Selective laser melting (SLM)

SLM technology is similar to SLS, they are even confused, because. and here and there metal powder and a laser are used. But these technologies have cardinal differences. In the SLS method, the powder particles are sintered together, while in the SLM method, the metal particles of the powder are melted and then welded together to form a rigid framework.

The model making process is similar to SLS technology. Here also a layer of metal powder is applied to the working area and evenly rolled over it. This work is performed by a roller or brush. Each layer height corresponds to a given product shape. The whole process takes place in a sealed chamber with an inert gas. A high power laser focuses on the metal particles melting and welding them together. The product is obtained similarly to FDM technology, the outer and inner walls are a solid, welded wall, and the space between the walls is filled according to the template.

SLM technology uses various metals and alloys. The main requirement is that when crushed to the state of particles, they must have certain flow characteristics. For example, materials such as stainless steel, tool steel, chromium and cobalt alloys, titanium, and aluminum are used.

The method is used where it is necessary to have a part with a minimum weight, and at the same time retaining its characteristics.

The technology is patented by Stratasys. Compared to other 3d printing technologies, PolyJet is the only one that allows you to make a model from various materials. This is achieved using a unique technology for feeding multiple materials in one print pass. This allows you to selectively place different materials within the same product or combine two materials, thus obtaining composite digital materials with characteristic predictable properties.

The PolyJet printing process is similar to conventional inkjet printing. Instead of applying ink to paper, 3D printers emit jets of liquid photopolymer, which forms layers in the work area and is fixed with ultraviolet radiation. Hardened products can be immediately taken and used, because. no additional post-hardening is required, as for example in SLA technology.

Because printing is done in layers, the overhanging parts require support material. For this, a gel auxiliary material which can be easily removed with water or by hand.

The technology allows you to create products of high precision. And thanks to the combination of different materials, the prototype is obtained as close as possible to the final product in terms of characteristics.

The 3D printing technologies discussed in the two parts of the article are not the only, but the most common technologies. In the next article, we will consider the materials used in these technologies, their differences and features.