Welding - Technologies Ensuring That Metals or Thermoplastics Are Joined through Fusion - Assignment Example

Normalization Customer Inserts His/Her Name Customer Inserts Grade Course Customer Inserts Tutor’s Name 22nd September, 2015. Overview Welding involves the use of different technologies to ensure that metals or thermoplastics are joined through fusion. This is a process whereby metals are joined by high temperature heating in order to ensure the base metals being joined melt and a filler material (weld pool) cools around the heated section to form a joint which is strong as the base material. In the process of undertaking welding, we came across some distortions that need explanation as shown in the diagrams below. The technique deployed in the process of welding ultimately affects the geometry weld in terms of the appearance of the weld. This is best outlined by the different weld during the lab experiment process due to several factors as outlined; a) Geometry: geometry affects welding since it involves the principles of understanding, calculating or measuring areas or volumes of shapes in the process of undertaking the welding exercise. Geometry assists greatly in the formation of joints and drafting of angles used in the welding process (Norrish, 2012). b) Oxygen Welding: Welding relies on oxygen to ensure proper welding and shielding in relation to metal welds. Therefore, the amount or ratio of oxygen on the weld metal has influence on the weld oxygen content. c) Overheating: In the process of welding, it is imperative to ensure that overheating does not affect the metal weld. For instance, overheating will ensure that the metal weld has longer time to solidify and longer exposure of the weld pool to the atmosphere (Pires, 2010). Questions. 1). How does the geometry affect your weld? The figures below, display sessions of welding proccess carried out by students of the unit Materials and Manufacturing 2 (group C4) division. The welding was conducted using the MIG (Metal insert Gas) machine as supervised by the instructor. Below each figure the description of the geotric effect of individual weld. Figure 1: Weldment of two rectangular piece of steel bar. This weldment was generated by the Lecturer. Figure 2: The difference between figure 1 and 2 is that, figure one has a continuous lineament of flux and thick weld. Whereas figure 2 displays similar feature but lesser thickness due to continuous welding albeit with incorrect amount of heating or flame from the welding gas. While undertaking welding, the welder did not ensure application of enough heating even though enough weld material was applied uniformly. As a result, the flux and thick weld were contiguous and lack uniformity in the beginning and at the end (Weman, 2011). This is compared to figure 1 whereby uniform heat and proper geometry were applied in producing the proper weld joint. Consequently, this weld joint is slightly disjointed and lacks proper handling in the sense that it does not hold all the sectors uniformly (Pires, 2010). More heating of the filler rod over the two metal bars would have achieved a proper and desired weld for these two metals. The metal weld above is just rightly done and only requires a little perfection with continued welding in the same vein as it was earlier done. The solution to the above weld problem would be to ensure the proper heating of the filler rods with use of adequate gas would ensure a proper weld joint as seen in figure 1. Figure 3: This figure lacks root fusion, worm hole which was contributed by opening at root of the weld joint. Therefore, in the process of undertaking welding a lot of air was sucked in contributing to the formation of a worm hole. Consequently, the weld joint above could have been contributed to improper position of the weld heating instruments from the metals. As a result, the weld joint has un-contiguous weld with limited and lack of uniform welding. This is compared to weld joint in figure 1 whereby proper geometry and heating was applied to the formation of a weld joint. Moreover, this weld joint was undertaken by holding the heat torch far away from the metals leading to a poor weld joint. As a result, it is imperative to ensure that heating over the weld joints is undertaken in a uniform manner (Norrish, 2012). The issue of lack of root fusion and formation of worm holes is often found within transformer-based machines since the arcs tend to wander between these two sides of the joint while seeking a path of least resistance. This is because the process of welding or heating two joints with a machine should be undertaken through proper geometrical positioning (Katayama, 2013). The solution to the above weld problem would be to reduce the arc length and thus providing better control in terms of directional welding which assists in increased penetration by the flame. Figure 4: The weldment has a worm hole and lacks inner run fusion. It also has air pore which indicate discontinuous welding as the weld does not appropriately hold the metals bars into the section adequately. The above weld was produced due to improper welding in regard to geometry and oxygen heating. Therefore, the weld joint is discontinuous which was contributed by holding MIG (metal inert gas) flame a little too far from the metal joint. Consequently, it seems the welder utilized a lot of gas with possible flow of around 60 to 80 cubic feet per hour which lead to improper formation of the weld joint (Weman, 2011). As a result, the process of welding led to cold fusion while the formation of a worm hole can be seen in the weld joint above. Utilizing high pressure and heat in the process of undertaking gas welding leads to poor weld joint formation. Since turbulence created by the high pressure pulls air from outside and the shielding provided by oxygen is not enough to ensure proper weld formation (Pires, 2010). As a result, the air pulled from outside by turbulence creates a worm hole and non-contiguous formation of weld joint at the base of the metal joint as witnessed in figure 4. This is unlike figure 1 whereby proper heating and geometry contributed to a uniform weld joint. Figure 5: Discontinuous welding and lack of inner-run fusion as witnessed in the figure r above due to high travel speed of weld. Lack of inner fusion and discontinuous welding in some cases is contributed to high speed of the weld. High speed welding in most cases leads to insufficient penetration since the arc does not stay at a place long enough to build sufficient heat. The diagram above shows the discontinuous weld joint which is thin a weak as a result of less heating (Weman, 2011). The technique used in the figure above is unlike the one utilized in the figure 1 whereby uniform speed was utilized in forming a continuous and uniform weld joint. The solution to the above problem would be to utilize uniform and constant speed in the process of undertaking welding (Katayama, 2013). Moreover, the process of welding in the figure 5 should be repeated over a slow heat over a certain period time. The positioning of the arc when utilizing the MIG gun also affects the tempo of welding contributing to various faults. Consequently, arc instability does not assist in ensuring that the geometry of welding becomes easy. In the case figure 5 above, the process was undertaken too quickly resulting in lack of inner fusion. Figure 6: Cold cracks witnessed in figure 6 above whereby the weld is too small to withstand stress. There is high penetration in the weld section leading to creation of a hole into the plate due to poor shielding. The figure 6 above is different from the figure 1 since the cracks and non-uniform fillers are witnessed in the weld sections. Cold cracking is contributed by residual stress especially from the base material which restrains the weld while at the same time the presence of hydrogen which is diffusible. This phenomenon is common within thick materials which create high resistance while at the same time presents an opportunity for fast cooling. As temperature increases within base materials due to high levels of heating, the base material allow heat sinks contributing to fast cooling rates. In some case, hydrogen is introduced to the weld via the filler metal or the atmosphere. This problem can be fixed through back stepping whereby the welding is done in one direction for a short period and then returns to weld in the opposite direction from where he started (Weman, 2011). As a result, the subsequent weld process and technique acts as a stress relieving. Consequently pre and post heat treatments and other general practices ensure that exposure to hydrogen are highly minimized. Figure 7: There is a lack of fusion in the welding. This might be due to poor welding techniques cause from weld metal been permitted to roll in front of the arc. The weld joint above was likely contributed by under filing the joint leading to poor weld joint. Under filling the weld joint contributes to a lack of fusion and thus the weld joint will likely not to hold for a long period of time. The welder did not have experience to enhance control of the welding gas and ensure proper filling of the joint in the process of welding. Filler metals ensure the risks of cracking are reduced while at the same time ensure proper penetration is achieved. In the figure 7 above, the welding process was undertaken poorly due to poor alignment of the weld arc and subdued penetration of the weld joints. As a result, the presence of defects is common and varied especially when under filling of the weld joint and use of low heat contributing to poor penetration (Katayama, 2013). The solution to the above issues is to undertake a more rigorous heat penetration and use of adequate filler material. This would ensure uniform and proper weld joint as witnessed by figure 1 above. Laboratory Safety In the process of ensuring proper welding is undertaken in the lab, a safety should be undertaken based on the current situation of the lab. The following observations on safety were undertaken in the process of assessing the lab on safety concerns. The table below summarizes the observations and categories the safety risks, solutions and categories for these safety factors. Description of hazard and safety issue Suggested solution to hazard Type of control hazard* 1 Low ventilator thus contributing to increased gases in the lab and hence reducing air circulation within the lab increasing chances of suffocation or heat exhaustion. Proper positioning of the ventilator within strategic location in the lab to increase air circulation. Engineering and Administrative 2 Lack of proper arrangement of equipment leading to hanging cables and strewn objects which could lead to accidents. All equipment should be stored well after use at a designated location in the lab. Administrative 3 Having unused electrical switches on which could contribute to fire hazards or accidents All electrical switches and equipment should be switched off after use. Administrative 4 Improper storing of equipment such as gloves or welding helmet thus contributing to increased occupational hazard in the lab and damage to equipment All tools, equipment used in the lab should be stored properly within designated areas. Moreover the work should be cleared before use. Administrative, Personal protection equipment References Katayama, S. (2013). Handbook of Laser Welding Technologies. Boston, MA: John Wiley and Sons. Norrish, J. (2012). Advanced Welding Processes: Technologies and Process Control. New York, NY: Woodhead Publishers. Pires, N. ‎ Loureiro, A. & ‎ Bölmsjo G. (2010). Welding Robots: Technology, System Issues and Application. Chicago, IL: Pelshiver. Weman, K. (2011). Welding and Welding Technology. London: Penguin Books. Read More