Metal 3D printing is a 3D printing technology that uses metal powder to directly print metal parts, also known as Metal Powder Sintering (SLM). 3D printing of metal powder requires good plasticity, as well as meeting the requirements of fine powder particle size, narrow particle size distribution, high sphericity, good flowability, and high bulk density. Currently, most metal powders used in 3D printers include stainless steel, aluminum alloy, cobalt chromium alloy, copper alloy Titanium alloys and nickel alloys. Iron based alloys are the most important and widely used metal materials in engineering technology, often used for the formation of complex structures and widely used in industries such as aerospace, automotive, shipbuilding, and mechanical manufacturing

The type of metal powder and the 3D printing process used determine the performance of the final product

Stainless steel powder

Relatively inexpensive metal printing materials have high cost-effectiveness, good corrosion resistance, and high strength, which can quickly and efficiently produce small batches of complex industrial components

Aluminum alloy powder

At present, aluminum alloys used in metal 3D printing mainly include AlSi12 and AlSi10Mg. AlSi12 is a lightweight additive used to produce metal powders with good thermal performance. The combination of silicon and magnesium gives aluminum alloys higher strength and stiffness, making them suitable for thin-walled and complex geometric shapes, especially in applications with good thermal performance and low weight. Aluminum alloy is the most widely used type of non-ferrous metal structural material in industry, Its density is low, specific strength is high, close to or better than high-quality steel, and plasticity is good. Research has shown that aluminum alloy used for 3D printing can achieve dense parts, fine microstructure, and mechanical properties comparable to or even better than casting formed parts. Compared to traditional process parts, its quality can be reduced by 22%, but its cost can be reduced by 30%.

Cobalt chromium alloy powder

Metal 3D printed cobalt chromium alloy powder is commonly used for printing various types of artificial joints and plastic surgery implants due to its excellent wear and corrosion resistance. In addition, it is also useful in the field of dentistry

Copper alloy powder

Copper, which has excellent thermal conductivity and thermal conductivity in thermal management applications, can combine design degrees of freedom to generate complex internal structures and conformal cooling channels

Titanium alloy powder

It is widely used in the aerospace field and utilizes the advantages of 3D printing to help optimize product design, such as replacing the original solid body with complex and reasonable structures, resulting in lower weight and better mechanical properties of the finished product. This not only reduces costs, but also enables lightweight production of various components

Nickel alloy powder

The oxidation and corrosion resistance characteristics of nickel alloys make them suitable for harsh environments at high temperatures and pressures. When nickel alloys are heated, a thick and stable oxide layer is passivated on the surface of the alloy to protect the interior from corrosion. Nickel alloys can maintain good mechanical properties over a wide temperature range

How to use powder materials for 3D printing

Using high-energy laser beams controlled by 3D model data to locally melt the metal matrix, while sintering and solidifying powder metal materials and automatically stacking layers to generate dense geometric solid parts

How to produce 3D printed metal powder

Metal powder manufacturing is a fundamental aspect of powder metallurgy. The different methods used to prepare metal powder include reduction, electrolysis, carbonyl decomposition, grinding, and atomization

The four most widely used methods for producing metal powders are solid-state reduction, electrolysis, chemical, and atomization

Most manufacturers use electrolysis and reduction methods to produce elemental metal powders. However, they are not suitable for manufacturing alloy powders. However, atomization methods tend to overcome this limitation, so manufacturers use them to produce alloy powders

Electrolysis is another method used to produce powdered metals. By selecting appropriate electrolyte composition, temperature, concentration, and current density, different metals can be deposited into sponge or powder shapes. This can then be washed, dried, reduced, annealed, and crushed. This method produces highly pure metal powders. Due to its high energy demand, it is basically used for highly conductive copper powders

Atomization method refers to the mechanical method of crushing molten metal into sizes smaller than 150 μ The method of pulverizing particles around m is classified according to the method of crushing metal melt. The atomization method includes two flow atomization, centrifugal atomization, ultrasonic atomization, vacuum atomization, etc. These atomization methods have their own characteristics and have been successfully applied in industrial production. Among them, the water vapor atomization method has the advantages of simple production equipment and process, low energy consumption, and large batch size, and has become the main industrial production method of metal powder

Performance requirements for metal powders in 3D printing

1. Purity

Ceramic inclusions can significantly reduce the performance of the final product, and these inclusions generally have a high melting point and are difficult to sinter into shape. Therefore, there must be no ceramic inclusions in the powder. In addition, the oxygen and nitrogen content also need to be strictly controlled. Currently, the powder preparation technology used for metal 3D printing is mainly based on atomization. The powder has a large specific surface area and is easy to oxidize, making it suitable for special applications such as aerospace, The customer has stricter requirements for this indicator, such as an oxygen content of 0.006% -0.018% in high-temperature alloy powder, 0.007% -0.013% in titanium alloy powder, and 0.010% -0.025% in stainless steel powder

2. Powder flowability and bulk density

The flowability of powder directly affects the uniformity of powder placement and the stability of powder delivery during the printing process. Flowability is related to powder morphology, particle size distribution, and loose density. The larger the powder particles, the more regular the particle shape, and the smaller the proportion of extremely fine powder in the particle size composition, the better their flowability; If the particle density remains unchanged and the relative density increases, the fluidity of the powder will increase. In addition, the adsorption of water, gas, etc. on the particle surface will reduce the fluidity of the powder

3. Powder particle size distribution

Different 3D printing equipment and forming processes have different requirements for powder particle size distribution. Currently, the commonly used powder particle size range for metal 3D printing is 15-53 μ M (fine powder), 53-105 μ The selection of metal powder particle size for m (coarse powder). 3D printing is mainly based on the classification of metal printers with different energy sources. Printers with laser as the energy source are suitable for using 15-53 due to their fine focusing spot and easy melting of fine powder μ M powder is used as a consumable material, and the powder supply method is layer by layer powder laying; A powder laying printer using an electron beam as the energy source, with a slightly thicker focusing spot, is more suitable for melting coarse powder and is suitable for use with 53-105 μ The coarse powder of m is mainly used; For coaxial powder feeding printers, a particle size of 105 to 150 can be used μ M powder is used as a consumable

4. Powder morphology

The morphology of powder is closely related to the preparation method of powder. Generally, when the metal gas state or molten liquid state is transformed into powder, the shape of the powder particles tends to be spherical, and when the solid state becomes powder, the powder particles are mostly irregular in shape, while the powder prepared by aqueous solution electrolysis method is mostly dendritic. Generally speaking, the higher the sphericity, the better the fluidity of the powder particles. 3D printing of metal powder requires a sphericity of over 98%, This makes it easier to lay and deliver powder during printing

The Importance of 3D Metal Powder Printing

Metal powder makes 3D printing faster and allows for rapid prototyping. Manufacturers can also modify designs more effectively. This method is also cost-effective because metal 3D printers only use the amount of material required to manufacture the required parts

Make designing complex machine parts easier and making the production of "impossible" machine parts possible