Manufacturing Methods and Materials Paper - Essay Example

Number Q2. FRICTION-STIR WELDING Friction-Star Welding is a solid method of joining metals (non-melted metal), which makes use of third bod tool in the joining of two facing surfaces. There is heat generated in between the tool and the material resulting to very soft region close to the FSW tool. The process the mixes two metal pieces mechanically at the joint area, then the metal which is softened (because of elevated temperatures) are joined through the use of mechanical pressure applied by the device (Mishra, 2005). This looks much like the joining of dough or clay. Primarily, it is used in aluminium, often on extruded aluminium or the non-heated treatable alloys, as well as on those structures in need of superior welding strength with the absence of a post welding treatment of heat. Friction stir welding was invented as well as experimented and proven back in 1991 at the Welding Institute in UK. The Welding Institute holds patents with regards to the process (Hidetoshi, 2006). Operation A non-consumable cylindrical –shouldered device that is constantly rotated, and with a probe that is profiled is at a constant rate fed to a boot joint in between the butted material and the clamped pieces. The probe is to some extent shorter than the required weld depth, and the tool shoulder riding on the work surface. There is frictional heat that is generated between the work pieces and the wear resistant welding. The frictional heat joined with that which is generated by mechanical mixing procedure as well as the adiabatic heat in the metals result to the stirred material softening but not melting. By way of pushing the pin forward, some unusual profile on its foremost face forces the material that is plasticised to the back where the forces of clamping support in the weld’s forged consolidation. The method of tool crossing along the line of welding within a metallic plasticised tabular shaft leads to severe solid state deformation that involves the base material’s dynamic recrystallization (Mishra, 2005). Advantages Friction stir welding s solid state nature results to several advantages compared to fusion welding process since it avoids the problems that are related to the liquid stage cooling. Matters like solute redistribution, porosity, liquation cracking and solidification cracking will be avoided during friction stir welding. Generally, friction stir welding produces a low defects concentration and is tolerant to variations in materials and parameters. Compared to the diffusion-welding methods, friction stir welding has potential advantage. These include: Enhanced security brought about by toxic fumes absence or the molten material spatter, It is automated on simple milling machines with ease- include low costs of set up as well as lesser training, No consumable- the threaded pin is made up of conventional device steel, low impact on the environment in general good weld appearance as well as well as minimal thickness under/over-matching hence dropping the requirement of costly machining after welding, ability to function in different positions whether vertical or horizontal etc. since there lacks a weld pool, Good mechanical properties within the as-welded conditions (Spierings, Schneider, & Eggenberga, 1995). Microstructures of Material Processed by Friction Stir Welding Friction stir welding process’ solid state while combined together with its special tool as well as the asymmetric nature leads to a highly distinguishing microstructure. This microstructure could be Brocken into several zones which include: The flow arm zone which is on the weld’s upper side and comprises of the material that he shoulder has dragged from the weld’s retreating side, around the stool’s rear and dumped on the advancing side. The stir zone- the nugget, dynamically crystalized zone, is the area of roughly deformed material which corresponds roughly to the pin location at the time of welding. Grains in the stir area are equiaxed roughly as well as often a magnitude order smaller than the grains within the parent material. The onion ring structure or several centric rings common occurrence is a unique characteristic of the stir zone. There has to been a firm establishment of the origin of the rings, even though variations in grain size, texture and particle number density have been suggested. Thermo mechanically affected zone- this does occur on the either of the stir zone sides. Within this area, the temperature and train are lower and the welding effect on the microstructure is smaller correspondingly. The microstructure is recognized as that of the parent material unlike in the stir zone, although significantly formed as well as rotated. Heat affected zone- it is common in all methods of welding. It is not formed at the time of welding but it is subject to thermal cycle. Lower temperatures compared to TMAZ, however, still may have some effect in case the microstructure is unstable thermally. References Hidetoshi, F. (2006). Friction stir welding of carbon steels. Materials Science and Engineering: A, 5. Mishra, R. S. (2005). Friction stir welding and processing. Materials Science and Engineering: R: Reports, 5. Spierings, Schneider, & Eggenberga. (1995). Comparison of density measurement techniques for additive manufactured metallic parts. Rapid Prototyping, 3. Q3. ADDITIVE MANUFACTURING AND SELECTED LASER SINTERING/ SELECTIVE LASER MELTING SLS (Selective Laser Sintering) is an additive technique of manufacturing that makes use of laser as source of powder to sinter material that is powdered (metal typically) automatically aiming the laser at points in space that are defined by 3D model, joining together the material to come up with a solid structure. SLS is like to direct metal laser sintering. Both of them are instantiations of a similar concept, however, they differ in technicalities. Selective laser melting makes use of a comparable concept, however, in SLM the material gets to be melted in full rather than sintered, enabling distinct properties such as porosity, crystal structure and the rest. SLS together with other AM procedures, is a new technology relatively that has been so far used for rapid prototyping mainly as well as for low volume production for component parts. Roles of production expand with the improvement of AM technology commercialization (Mazzoli, 2013). The development as well as patenting in the 1980s by Dr. Carl Deckard and Dr. Joe Beaman, an academic adviser in the University of Texas at Austin. Sponsored by DARPA, Beaman and Deckard got involved in the resultant start-up firm DTM, which was established to undertake the designing as well as building of selective laser sintering machines. In the year 2001, DTM was acquired by 3D system which had been the largest competitor for DTM and the technology of selective laser sintering. The current patent with regard to Deckard’s selective laser sintering technology was issued in the year 1997 and got to expire in 2014 (Evila, Guillem, Lidia, Joaquim, & Ciro, 2014). Performance The additive manufacturing layer technology includes using high power laser such as carbon dioxide laser, in fusing small metal, plastic, glass or ceramic particle powders into some mass with desired 3D shape. Powdered material are selectively fused by the laser through scanning cross sections that are generated from the part’s 3D digital description for instance the scan data or a CAD file, on the powder bed surface. After the scanning of each cross section, the layer thickness lowers the powder bed; a new material layer is applied on top and repetition of this process goes on till completion of the part. Advantages The advantage realised in the technique is that unlike the other additive manufacturing methods, for instance fused deposited modelling (FDM) and the stereo lithography (SLA), sensitive laser sintering requires no support structures because the part under construction is surrounded by powder that is unsintered all the time. That makes it possible for the construction of prior impossible geometries (Mazzoli, 2013). SLS does provide freedom for building more durable and complex parts very quickly. It also provides a better functionality when compared to other technologies of rapid prototyping. Customers who leverage the process of SLS find real advantage in the fact that it allows them to test the parts within real world environments. Typical Microstructures of Materials Processed by SLS/SLM Some SLS machines make use of single component powder, for instance, the direct metal laser sintering. Production of powders is often done by ball milling. Most Selective Laser Sintering machines make use of two component powders, either powder mixture or coated powder typically. In the case of single component powders, only the particle’s outer surface is melted by the laser (surface melting), fusing the solid cores that are not melted to each other as well as to the previous layer. When SLS is compared with the additive manufacturing other methods, it is found to produce parts from a wide range relatively for powder materials available for commercial. Such include polymers like nylon (glass filled, neat or with further fillers) or even polystyrene, alloy mixtures, metals like titanium and steel, and composites as well as green sand (Dimitrov & Beer, 2014). Physical process could be partial melting, full of melting or liquid phase sintering. Contingent to the material, up to one hundred percent density may be achieved with properties of materials likened to those from conventional methods of manufacturing. In most cases, large part numbers are able to be packed in the powder bed making it possible for very huge productivity. Selective Laser Sintering is being used widely across the world because of its capacity to create very complex geometries from digital CAD data directly. Even though early in the design it started as means of building parts of prototype, its use in limited run manufacturing is increasing for the production of end use parts. One of the least expected selective laser sintering rapidly growing application happens to be its usage in art. References Dimitrov, & Beer. (2014). IMPROVEMENTS IN THE CAPABILITY PROFILE OF 3-D PRINTING: AN UPDATE. South African Journal of Industrial Engineering , 12. Evila, L. M., Guillem, V., Lidia, S., Joaquim, C., & Ciro, A. R. (2014). Rapid tooling using 3D printing system for manufacturing of customized tracheal stent. Rapid Prototyping Journal, 12. Mazzoli, A. (2013). Selective laser sintering in biomedical engineering. Proques, 13. Read More