3d Printing.docx

3D PRINTING Additive Manufacturing (AM) is the technology that builds 3D objects by adding layer-uponlayer of material, whether the material is plastic, metal, concrete or one day…..human tissue. The term AM encompasses many technological terms, including subsets like Rapid Prototyping (RP), Direct Digital Manufacturing (DDM), layered manufacturing, additive fabrication and most commonly used 3D Printing. The integral parts/components for 3D printing are a computer, 3D modelling software, machine equipment and layering material. The objects created/fabricated using 3D Printing can be of almost any shape or geometry. It is formed under the control of a computer using a digital 3D model. 3D model (Computer Aided Design) sketch is to be made and fed to the machine. The 3D printer then reads the data from the CAD file, and lays upon a layer of liquid, powder, sheet material or any other. Successive layers are added, layer upon layer and the complex 3D model/object is fabricated. There are various types of 3d printers, the following are a few of the most popular ones. 1. Stereolithography (SLA): The oldest in the history of 3d printing. The process involves a uniquely designed 3d printing machine called a stereolithograph apparatus (SLA) which is capable of converting liquid plastic to a predefined solid 3d object. This method is widely used for prototyping as it is cheaper than other means of prototyping. When 3D. model is fed to the machine, a special kind software processes the CAD model to generate an STL file that contains information of each layer. The machine exposes the liquid plastic and laser starts to form the layer of the item. After plastic hardens, platform of the printer drops a few mm inside the tank and the next layer is formed. This continues till the printing is completed. Then object is placed in an ultraviolet oven to finish processing. 2. Digital light Processing (DLP): This is very similar to stereolithography. Both SLA and DLP works with photopolymers but for 3D DLP a more conventional light source such as arc lamps are being used. The material to be used for printing is liquid plastic resin that is placed in a transparent resin container. The resin hardens quickly when exposed to a large amount of light. Here the printing speed is much higher. The amount of material wastage is much less than SLA. 3. Fused deposition modelling (FDM): Here the material that can be used for printing is high performance engineering grade thermoplastic, good mechanical, thermal and chemical quality can be achieved with FDM, hence not just prototypes, but also concept models and final end use products can also be printed using this technique. CAD model is fed to the machine and each layer to be deposited is computed. The machine heats the thermoplastic to its melting temperature and extrudes it through a nozzle on the base plate. When the thin layer of plastic cools down and hardens, the computer calculates the translation and rotation of the nozzle and the base plate and another layer is extruded. To extend support to the material extruded, the nozzle also extrudes special support material around the base material, which can be removed by various methods at a later stage.

4. Selective Laser Sintering (SLS): It uses a high power laser as a power source to form solid objects. The working principle is similar to SLA, but the major difference between the two is that, SLS uses powder material instead of liquid resin that is being used in SLA. Here support material is not needed as the finished layers are supported by the unsintered material. A wide variety of material can be used in this technology like nylon, ceramic, glass, aluminium, steel, silver etc. 5. Selective Laser Melting (SLM): It is similar technology to SLS, here a high power laser beam is used to fuse and melt metallic powder together. Fine metallic powder is evenly distributed on a plate then each layer is fused according to the shape and size required by a high power laser that is directed towards the plate. Due to the high energy of the laser, the metallic powder melts completely. After the layer is completed, the process starts over again for the next layer. Stainless steel, titanium, aluminium are few of the metals that can be used for SLM. This method is widely used to create complex geometries and structures, especially those with hidden voids and channels. A lot of application is seen in aerospace industry. The major benefit of 3D printing lies in those areas where conventional manufacturing reaches its limit. Usually while designing a product, production determines the limitation in realizing the design. Most of the times, the ideal requirement of the product may not be met due to the limitation of manufacturing. Here the technology of 3D printing comes into picture. Most of the components designed in the aerospace sector are not optimized to the fullest because of limitations of realization. The implementation of 3D printing enables a design driven manufacturing process, where design determines production and not the other way round. 3D printing provides a high degree of design freedom by allowing highly complex and extremely light weighted and stable structures to be realized. At present 3d printing technology is being used extensively in many areas. Rapid manufacturing is new method where companies are using 3d printers for short run/small batch custom manufacturing. Here the printed object is not just a prototype but can be used by the end user also. A huge application is seen in the automotive industry where companies are using 3D printing for manufacturing, restoring and repairing for a long time now. Koenigseg use carbon fiber parts in their One:1 car. With the use of 3D printing, the company saved 40% of the cost and developed 20% faster when compared to traditional methods. Audi is using 3D printing to produce spare parts. Boeing have been exploring the use of 3D printers for a longtime. It was estimated that more than 20,000 3D printed parts (mostly titanium) are being used in their aeroplanes. GE engineers working on aircraft manufacturing, recently demonstrated the capabilities of 3D printing by printing a mini jet engine that roared at 33,000 rotations per minute. A –wide use of 3D printing is seen in the aerospace industry. Multiple organizations, including NASA has been working to perfect the shielding on shuttles using 3D printing. Although the manufacturing needs at the present state are being met by conventional technologies, but the possibilities of exploring the implementation of 3D printing is the need of the hour. 3D printing will not only enable us to realize complex structures with ease but

will also enable the designers to think of a more optimized design which were discarded due to limitations in realization.