Fusion Welding and Non-Fusion Welding: Overview

Fusion welding and non-fusion welding
Fusion welding is defined as a welding process of using heat by melting the base of metals in order to joint similar types of metals together. Filler is used in this welding process to provide bulk and strength to the welded joint [1]. Whereas non-fusion welding which is known also as solid state welding is a welding process where a particular amount of heat is applied to the joining metals which essentially below the melting point of the base metals that being joined. Non-fusion welding processes do not use any addition of filler metal [2]. One notable difference in these two types of welding processes is in fusion welding, when the welded materials’ temperature rise above the melting point (or liquidus temperature for alloy) it will produced a fusion zone with partially melted zone occurred on the side of the fusion zone. Next to it are the heat affected zones which can be distinguished by the colour formed after the welding process [3]. For instance, blue colour shows that certain part or zone is the high-temperature heat affected zone while red is the low-temperature heat affected zone. On the other hand, non-fusion welding allows the joining metals to deform plastically with no fusion zone occurring and little or no heat affected zone depending on how much heat is applied to the metals [3].

Figure 1: The left hand side is the example of fusion welding while the right hand side is non-fusion welding taken from [3] with the differences describe as above.
The main advantage of fusion welding processes is its portability which make it easier to be carried on a truck or trailer and even human’s back. One type of fusion welding is oxyacetylene welding where the whole welding components are relatively small and can be carried to anywhere easily. In addition, it is independent from any external energy sources which make fusion welding as preferred choice in certain situation. Given a situation such as at oil rig, it is much more convenient to have oxyacetylene welding kit since its portability makes it the preferred choice in this kind of situation [4]. As in for disadvantage, the significant one for fusion welding is the distortion. The joining metals are provided with heat until they reach their melting point on which they undergo significant thermal expansion and right after that a contraction upon cooling. This sudden change in temperature causes both joined metals to distort. The heat affected zones on the welded metals are subject to loss of mechanical properties such as strength or hardness. When metals undergo a thermal process, in this case fusion welding they will set to lose their mechanical properties as stated above [5].
One main benefit of the non-fusion welding processes is the welded metals retain the similar mechanical properties of their parent metals. This is true because for non-fusion welding the heat applied is below the melting point (where thermal expansion can be neglect) of the metals hence the weld will retain the strength or hardness of the parent metals. Therefore dissimilar metals can be joined since thermal expansion and conductivity is of much less importance in this type of welding [6]. On the other side of it, the main disadvantage of non-fusion welding is a thorough surface preparation is required such as removing oxides (impurities), brushing or sanding [7] because the impurities on the surface of the metals will give negative effects during the welding process. Even though it is not significant but non-fusion welding uses quite expensive equipment so it might not be a suitable choice to save cost.
Manual arc welding, TIG welding and MIG welding
Manual arc welding is defined as a process when an arc is drawn between a coated consumable electrode and the work piece, then the metallic core-wire in the coated electrode melted by the arc and been transferred to the weld pool as the molten drops. The coating of the electrode also melted to form a gas shield around the arc and the weld pool to protect the cooling weld from atmosphere [8]. In order to handle manual arc welding, some safety measures should be taken into account, firstly practitioner has to wear protective clothing and equipment. We need a leather gloves, fireproof overalls (or shirts with trousers), adjustable helmet with approved welding screen on it because arc welding produces UV sparks that can damaged eyes. For the electrical part, make sure to check all the welding cables are in good condition and all electrical connections are tight and good order. Not to forget, only use welding equipment under the supervision of competent person [9]. This type of welding process is suitable for an outdoor-typed welding task because of its portability and mobile. Hence make it ideal for an outdoor work such as repairing machine at farm.
TIG welding also known as tungsten inert gas welding is a welding process that uses non-consumable tungsten electrode to produce weld. It is being protected from the atmosphere to prevent oxidization by using an argon shield (inert gas). It is known to produce a very clean welds and able to weld more metals than any other process [10, 11]. One of the safety precautions that can be taken while using TIG welding equipment is do not carry the welding process in confined spaces. The reason behind this is that TIG welding contains inert gas such as argon gas which can be harmful to the welder if it is exposed at certain exposure level. In addition to that, implementing properly designed ventilation systems also help to prevent welders from being exposed terribly to the argon gas. The electric arc from this TIG welding equipment produces ultraviolet light radiation, so it is a must to cover all skin before the welding process is done. Uncovered skin might get burn if expose to this kind of radiation so proper protective gear should be worn before the activity started [12, 13]. TIG welding is preferably to be used in a closed area in order to ensure the effect of argon shield so that an oxidization of metals can be prevented. If it is being used at open area, the presence of wind will disturb the argon shield
Metal Inert Gas (MIG) welding is another welding process where continuous and consumable wire electrode is fed through a welding gun. Similar to TIG welding, the wire electrode is being protected by a shield of argon gas [14]. In order to prevent accidents to occur during the welding process, welding mask have to be wear by welders because the sparks and light generated from the MIG welding is extremely bright. A direct contact with the light from MIG welding could cause burnt for welders’ cornea. Similarly to TIG welding, weld in properly-ventilated spaces to prevent the metal fumes which can cause harm to human body [15]. It is also preferred to use in a properly-ventilated close area to protect the gas shield so that the welded metals will not be oxidized.
Bronze welding and Oxy cutting
Bronze welding is a welding process that joins metals in which the edges of both metals are being heated to a temperature that is below their melting point before bronze alloy is simultaneously melted and forced to flow over the edges to join with them. One of the benefits of this welding process is it produces a strong and ductile of joint metals [16]. Generally the safety precautions that can be taken when undergo this process are similar as any other welding processes such as wearing closed shoes, protective gloves and coat, as well as welding helmet. Bronze welding is suitable to be used as on-site repair application because the equipment is simple and easy to use. Furthermore, it takes much shorter time to weld the metals thus less time consuming [17].
The definition of oxy cutting is the use of fuel gases and oxygen to cut metals. Pure oxygen is used so that the flame temperature is risen up in order to allow localized melting of metals in a room temperature. In oxy cutting, a cutting torch is used to heat metal to kindling temperature and stream of oxygen is applied on the metal so that the metal burns in the oxygen stream and flows out as an oxide slag. It is useful to weld and repair pipes and tubes. As a safety measure, welding goggles should be worn all time during operating this technique to avoid the glare and flying sparks damaging eyes of the welder. A potential of fuel leakage also must be seriously taken as precautions because a leakage of fuel gases may cause fire during this process. Besides that, increase the ventilation around the welding area so that any hazardous chemical vapour as the result of the welding process will not cause any medical harm to welders [18]. Oxy cutting is a preferred choice when it comes to a mass production of cutting metals because it is easier to handle by human and also does not consume a lot of one’s energy.

Conclusion
In a big industry, welding is the most preferred choice to joint materials together taking consideration of the cost of welding compared to casting and forming which have a significant difference. Besides that, welding is more practical method since it can joint to different types of materials together compared to casting and forming where it only suits for one type of material at a time.
Oxy cutting on the other hand is more beneficial than conventional cutting method such as sawing or drilling in term of a large scale work. It does not use a massive amount of workforce to cut materials such as large diameter pipe if compared to sawing which also could take a substantial amount of time to get the work done.
In conclusion, in the large-scale industry welding and oxy cutting must be the most suitable choices to joint and cut materials respectively providing they make things easier to be done to fulfil the requirement of this type of industry area.

References 1. M.P.Groover, “Overview of Welding Technology – Types of welding processes”, Fundamentals of Modern Manufacturing, 3rd Edition, pp. 691, 2007. 2. “Solid State Welding” Internet: http://www.keytometals.com/Article51.htm [May 15, 2011]. 3. R.W.Messler Jr, “Classifying welding processes – Fusion versus nonfusion”, Principles of Welding – Processes, Physics, Chemistry and Metallurgy, pp. 23-25, 1999. 4. E.E.Levi. “Welding-gas, huge benefits with low-cost outfits: Solution with effective, powerful advice” Internet: http://www.welding-advisers.com/Welding-gas.html 2011[May 14, 2011] 5. D.J.Grieve. “Welding Processes: Fusion welding processes” Internet: http://www.tech.plym.ac.uk/sme/strc201/weld1.htm February 23, 2009 [May 14, 2011] 6. “Solid State Welding” Internet: http://www.keytometals.com/Article51.htm [May 15, 2011] 7. D. Kopiolevich. “Solid state welding” Internet: http://www.substech.com/dokuwiki/doku.php?id=solid_state_welding_ssw, May 17, 2009 [May 15, 2011] 8. “Manual Metal Arc Welding”, Internet: http://www.stellite.co.uk/WeldingProcesses/ManualMetalArcWelding/tabid/71/Default.aspx 2010 [May 16, 2011] 9. J. Sharples. “Perform Routine Manual Metal Arc Welding: Safety theory notes” Internet: http://www.slideshare.net/jokay/safety-notes-manual-metal-arc-welding 2006 [May 16, 2011] 10. R.W.Messler Jr, “Classifying welding processes – Fusion versus nonfusion”, Principles of Welding – Processes, Physics, Chemistry and Metallurgy, pp. 51, 1999. 11. “TIG Welding Tips”, Internet: http://www.millerwelds.com/resources/tech_tips/TIG_tips/ 2011 [May 16, 2011]. 12. “Gas Shielded Arc Welding Safety Precaution”, Internet: http://mewelding.com/welding/gas-shielded-arc-welding-safety-precautions 2011 [May 16, 2011] 13. E. Steeley. “Tig Welding Safety”, Internet: http://www.ehow.com/facts_7473290_tig-welding-safety.html December 9, 2010 [May 16, 2011] 14. “Gas metal arc welding”, Internet: http://en.wikipedia.org/wiki/Gas_metal_arc_welding May 4, 2011 [May 16, 2011] 15. “Welding safety’, Internet: http://www.mig-welding.co.uk/welding-safety.htm [May 16, 2011] 16. “Bronze Welding”, Internet: http://www.meg.co.uk/courses/21.php [May 16, 2011] 17. “Advantages of braze welding”, Internet: http://www.welding-technology-machines.info/braze-OR-bronze-welding/advantages-of-braze-welding.htm [May 16, 2011] 18. “Oxy-fuel welding and cutting”, Internet: http://en.wikipedia.org/wiki/Oxy-fuel_welding_and_cutting May 4, 2011 [May 16, 2011]

References: 1. M.P.Groover, “Overview of Welding Technology – Types of welding processes”, Fundamentals of Modern Manufacturing, 3rd Edition, pp. 691, 2007. 2 3. R.W.Messler Jr, “Classifying welding processes – Fusion versus nonfusion”, Principles of Welding – Processes, Physics, Chemistry and Metallurgy, pp. 23-25, 1999. 4. E.E.Levi. “Welding-gas, huge benefits with low-cost outfits: Solution with effective, powerful advice” Internet: http://www.welding-advisers.com/Welding-gas.html 2011[May 14, 2011] 5 6. “Solid State Welding” Internet: http://www.keytometals.com/Article51.htm [May 15, 2011] 7 8. “Manual Metal Arc Welding”, Internet: http://www.stellite.co.uk/WeldingProcesses/ManualMetalArcWelding/tabid/71/Default.aspx 2010 [May 16, 2011] 9 10. R.W.Messler Jr, “Classifying welding processes – Fusion versus nonfusion”, Principles of Welding – Processes, Physics, Chemistry and Metallurgy, pp. 51, 1999. 11. “TIG Welding Tips”, Internet: http://www.millerwelds.com/resources/tech_tips/TIG_tips/ 2011 [May 16, 2011]. 12. “Gas Shielded Arc Welding Safety Precaution”, Internet: http://mewelding.com/welding/gas-shielded-arc-welding-safety-precautions 2011 [May 16, 2011] 13 14. “Gas metal arc welding”, Internet: http://en.wikipedia.org/wiki/Gas_metal_arc_welding May 4, 2011 [May 16, 2011] 15 16. “Bronze Welding”, Internet: http://www.meg.co.uk/courses/21.php [May 16, 2011] 17 18. “Oxy-fuel welding and cutting”, Internet: http://en.wikipedia.org/wiki/Oxy-fuel_welding_and_cutting May 4, 2011 [May 16, 2011]