This article examined the history of three-dimensional (3D) metal printing technology, various types of methods, and their advantages and disadvantages. Selective Laser melting (SLM) was compared with regards to consumables, working methods, limitations, capabilities, and applications. Examining each method in turn reveals that the superiority of each one depends on the materials that are intended to be used as the basis of any type of light or heavy parts. The prepared sample by SLM process, which belongs to the family of 3D printing, is fusion powder, and the materials used in both processes are granular metals. This technology is suitable for complex parts, which cannot be made by traditional methods due to their high cost, with excellent mechanical properties for the industry, plastic, and dentistry applications. This technique uses metal 3D printing technology with various levels of porosity. Every day, metal printing provides greater benefits to industries. However, this technology has its own disadvantages, which include its lack of both suitablity and cost-effectiveness for manufacturing parts with traditional methods.

In this study, a Selective Laser sintering 3D printer has been designed and built. 3D Laser printing is one of the flexible additive manufacturing methods, which can use different powdered materials. Recently, additive manufacturing technologies have been introduced into the pharmacy, and in August 2015, they received FDA approval as the three-dimensional drug products. By using additive manufacturing in the pharmacy, controlled release, dosage tailored to the characteristics of individuals, the desired morphology of the drugs can be achieved and we move toward the personalization of the medicine. One of the important issues is to determine the properties of tablets before printing. In this paper, the effect of important variables of Selective Laser sintering on tablet breaking force is investigated with the aid of central composite design and modeling. Using the proposed modeling, the value of each variable can be determined so that the tablets are printed with the required breaking force. The cylindrical tablets with a diameter of 1. 2 cm and a height of 3. 6 mm were printed for use in the experiments. To fabricate tablets, the thermoplastic polymer, Kollicoat IR (75% polyvinyl alcohol and 25% polyethylene glycol copolymer), was used and 5% paracetamol (acetaminophen) was added. Also, some edible black color was added to increase the absorption of Laser light. Laser feed rate, the percentage of the tablet infill density and percentage of the added color are the studied variables. According to the results obtained in the considered range, by increasing Laser feed rate, tablet breaking force decreases, but tablet braking force increases by increasing infill density and amount of added color.

Selective Laser sintering is one of the methods of additive manufacturing based on powder bed which is widely used in various industries today. In this process, the amount of laminated mass has a high impact on reducing the porosity and quality of the final parts produced. For this purpose, in this study, a mechanism was designed and developed to investigate and achieve the maximum amount of laminated mass in a laminating process. The optimal state was obtained using the central composite design method. The results show that the parameters of blade velocity, angle under blade, and excess powder percentage have a greater effect on the amount of laminated mass, respectively. The optimized laminated mass was predicted by the experimental model to be 0. 811 g, in which case the velocity is 2. 78 cm / s, the blade angle is 3. 1 °,and the initial powder content is 159%. To validate the model, the experimental experiment was performed based on the parameters of the optimal state, in which the laminated mass was measured 0. 83 g, which shows that the error of the obtained model is 2. 2%.

The field of Additive Manufacturing (AM), also known as 3D printing, has experienced rapid advancements, revolutionizing traditional approaches to object design and production. This innovative process entails the layer-by-layer deposition of materials in three-dimensional coordinates based on digital files. Additive manufacturing has gained widespread adoption across diverse sectors such as aerospace, robotics, education, medicine, pharmaceuticals, automotive, and construction. Among the techniques employed in AM, the powder bed fusion process is commonly used, including methods like Direct Metal Laser sintering (DMLS), Electron Beam Melting (EBM), Selective Thermal sintering (STS), Selective Laser Melting (SLM), and Selective Laser sintering (SLS). The SLS 3D printer, as a powder bed fusion technique, has undergone multiple modifications to enhance precision and reduce operational expenses. By utilizing a high-power Laser, the SLS 3D printer Selectively fuses or sinters powdered materials, typically polymers or metals, to fabricate three-dimensional objects. The printer bed is heated to just below the material's melting point, and the Laser precisely targets specific areas based on the digital design file. As the Laser heats the powder particles, they fuse together, forming a solid layer. This layer-by-layer process continues until the 3D object is fully realized. The SLS 3D printer has found practical applications in sectors such as aerospace, medicine, and pharmaceuticals. In the aerospace industry, it is employed to manufacture lightweight components featuring intricate geometries. The medical field benefits from the SLS 3D printer's ability to produce customized and precise implants and prosthetics. Additionally, the pharmaceutical industry utilizes this technology for the creation of drug delivery systems with controlled-release properties. The SLS 3D printer has undergone significant advancements as a powder bed fusion method, allowing for the production of highly precise and customized items with complex geometries. Improvements have been implemented to enhance accuracy and reduce operational expenses. Its versatility makes it suitable for diverse industries.

Selective Laser sintering is one of the most popular additive manufacturing techniques used in recent years, due to its capability to build complicated geometries without the support structure. Thermal history plays a major role in the mechanical properties of the final product. In this research, the effects of different cooling down processes on mechanical properties of PA12 parts produced by Selective Laser sintering have been investigated. For this purpose, temperature changes of different points inside the powder bed during the built and cool down process have been monitored and recorded. Crystallization kinetics for the produced parts has been investigated by the non-isothermal crystallization model to help the interpreting of the results. Differential scanning calorimetry and X-ray powder diffraction (XRD) analysis were performed to find the degree of crystallinity and its possible correlation with mechanical properties. The results indicated that the parts cooled with the lower cooling rate showed 5% higher tensile strength and 10% more crystalline structure fraction comparing with the other two cool down methods. The results of crystallization kinetics for the produced parts by non-isothermal crystallization model showed that a lower cooling down rate led to slower crystallization in the component. The degree of crystallinity of the slow cooling down parts was about 10 percent more than the other samples. Based on the XRD results, the crystalline structure of the parts in all cooling down processes was the same (γ form crystal).

Rapid prototyping with Low Frequency Selective Electrical Discharge sintering (SEDS) is a new method in manufacturing of parts and masters. In this method, an electrical plasma arc provides the required thermal energy for initial binding. A polymeric coated metal powder as raw material is used in SEDS and initial binding is constructed by liquid phase sintering. Sequential layers are manufactured according to their CAD models. A moving electrode scans entire of the surface and the generated thermal energy of the plasma arc is exerted to the particle powders in the Selective points of the powder bed. After manufacturing of all of the layers, the green part is removed from the built-chamber of the SEDS system and is put in the appropriate furnace to complete the sintering process. Then for decreasing the porosity and increasing the strength of the part, the infiltration process is done. The manufactured part in the SEDS method is a functional part. The SEDS method has some valuable potential which provide the manufacturing of the large parts and masters.

In this research, the thermal analysis of additive fabrication by DMLS method has been investigated. In the DMLS method, the metal powder is melted by a Laser heat source and finally a solid t hree dimensional piece is formed This analysis was performed by finite element method in Abaqus software. L aser heat distribution is considered Gaussian. T he mechanical and thermal properties of the powder are considered as a function of melting temperature. Finally, the results obtaine d by the finite element method are compared with previous re searches. The effects of Laser speed and power on temperature distribution have also been investigated.

In order to understand the impact of layer-wise scanning direction in the Selective Laser sintering process, test coupons were manufactured for mechanical testing from Dura FormTM Polyamide powder. The effects of Laser energy density, varying between 0.003 and 0.024 J/mm2 were examined in test specimens rotated 90o through the Z axis. SLS machines do not always facilitate ‘cross-hatching’ of layers and therefore orientation has a major influence on part quality. When employed, the cross-hatching technique scans successive layers perpendicularly to the previous. Studying how parts perform with scan lines in a common direction, will assist in the understanding of how SLS parts behave in practice. Results showed that physical density, tensile strength and elongation rose with energy density up to 0.012 J/mm2. This initial rise was due to a continued improvement in particle fusion with increasing energy density. Above 0.012 J/mm2, these properties started to decline at different rates depending on their orientation (scan direction) on the part bed. Specimen’s oriented perpendicularly to the X axis exhibited a greater elongation at the expense of tensile strength, when compared to parallel specimens.

One of the main goals of researchers in metal powders Laser sintering, is optimization of process parameters in order to close out the main properties of the raw materials have been produced to the piece. For this purpose, many experiments have been carried and parameters such as density, hardness, micro hardness, strength, surface finish, appearance, and residual stress have been studied. In this paper the influence of parameters such as Laser power, scanning speed, and powder material and etc. on output parameters such as penetration depth, strength, balling phenomenon is investigated. In order to produce a multi-layer fully dense parts by the process of pulsed Laser, to optimize the performance of the Laser and material parameters at first, it is necessary to single layers is investigated. Experiments carry out on free powder bed depth is 5 mm. Each piece of a single layer on the substrate with once Laser scanning powder is produced. Movement of the Laser beam on the surface produce a washer with 20mm diameter.