Selective laser melting (SLM) and direct metal laser sintering (DMLS) are two metal additive manufacturing processes that belong to the powder bed melting 3D printing series.
The two technologies have many similarities: both use laser scanning and selectively fuse (or melt) metal powder particles, glue them together and build them layer by layer. Similarly, the materials used in both processes are granular metals.
The difference between SLM and DMLS is due to the basis (and patents) of the particle bonding process: SLM uses metal powder with a single melting temperature and completely melts the particles, while in DMLS, the powder is composed of materials with variable melting points at high temperatures Fusion at the molecular level.
3d-printing-china.com provides 3D printing services for various metal materials such as stainless steel, die steel, titanium alloy, aluminum alloy, and bronze.
PTJ meets or exceeds the quality standards of the world’s most demanding industries with our state of the art equipment and quality standards. Our precision and productivity is made possible by our ultimate success factor: the presence of skillful, knowledgeable PTJ experts in SLM 3d printing and more additive manufacturing parts.
SLM, the full name of selectivelasermelting, is mainly used in molds, dentures, medical, aerospace, etc.
Metal 3D printing is equipped with at least 500W fiber laser, with collimation system and high-precision scanning galvanometer, it can obtain fine spot and optical quality
Therefore, SLM metal 3D printing has high molding accuracy
Similarly, SLM technology uses pure metal powder, which is completely melted before fusion, and the strength of the product is higher than that of SLS
In the metal 3D printing process, in order to prevent the oxidation of the metal powder combined with the air, it needs to be carried out in an inert gas (oxygen-free) environment
The principle of SLM/DMLS forming process is basically the same as that of SLS. The DMLS technology uses a mixture of materials composed of different metals, and each component compensates each other during the sintering process, which is beneficial to ensure the production accuracy. In order to ensure the rapid melting of metal powder materials, SLM technology requires a high-power density laser, with a spot focused to several tens of μm to several hundreds of μm. SLM technology currently most commonly uses fiber lasers with excellent beam modes. The laser power is above 50W, and the power density is above 5×106W/cm2.
In SLM, almost all process parameters are set by the machine manufacturer. The layer height of metal printing is generally controlled between 20 and 50 microns, depending on the nature of the metal powder (fluidity, particle size distribution, shape, etc.) and the performance requirements of the final printed component.
The small metal 3D printing equipment has a print size of 100 x 100 x 100 mm, which is mainly used in the dental and jewelry industries. The largest size of the relatively mature large metal printing equipment on the market is 500 x 280 x 850 mm. The dimensional accuracy that metal 3D printers can achieve is about ±0.1 mm.
The metal powder in SLM is highly recyclable: less than 5% is usually wasted. After each printing, the unused powder is collected, sieved, and then topped up with fresh materials to the level required for the next build.
The support structure in metal printing is essential to the successful completion of the printing, but the supported printing will greatly increase the amount of materials required and increase the printing cost.
Due to the high processing temperature of metal, a support structure is always required in metal printing, and the support structure is usually constructed using a lattice pattern.
In the process of metal 3D printing, it is very important to add necessary support to the shape and performance requirements of the printed part. The support structure mainly plays a role in three aspects:
Parts are usually oriented at an angle to minimize the possibility of warping and maximize the strength of the part in key directions. However, this will increase the amount of support required, lengthen printing time, and increase printing costs.
The use of laser random scanning printing mode can also minimize warpage. This printing method can prevent the accumulation of residual stress in any specific direction and will add a characteristic surface texture to the part. Due to the high cost of metal printing, simulation software is usually used to simulate the printing process before printing to find possible problems in advance. Topology optimization algorithms are used not only to maximize mechanical performance and manufacture lightweight components, but also to minimize the need for support structures and the possibility of warping.