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The strength and hardness of lead is relatively low, as a result, it is easy to have lead deformed. The most common manufacturing processes of lead are cold stamping, rolling, extrusion, die casting and joined by welding, etc. [1] [2]
Figure 1 Rolling process [8]
Cold rolling is a process in which lead will pass through rollers at temperatures below its recrystallization temperatures. By doing this, the yield strength and hardness of itself can be increased. In micro level, defects will be introduced into the crystal structure of lead. Thus, creating a hardened microstructure that prevents further slip. Since the lead is under room temperature, it will be less malleable than lead that is above the recrystallization temperature. Due to this, cold rolling is in need of a more expensive and labour-intensive work than the hot rolling. In addition, Cold rolling can also act to decrease the grain size of lead caused by Hall-Petch Hardening. [5]
Hot rolling: Hot rolling is processed at very high temperatures, higher than the recrystallization temperature of most metals. n hot rolling of lead, a piece of lead embryo was taken, sent for pre-processing, and then flattened into a large reel. At high temperature, pass a series of rollers to reach the size it completes. [6]
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Cold stamping: In cold stamping, intense pressure is used to shape metal sheets into the form people needed. [11] For cold stamping, it has advantages such as lower cost, fast, flexible, and fewer cycles of making mould, as no metal dies were needed. However, its disadvantage is that the production process can cost much time.
Figure 4 Cold stamping [13]
Die casting: In the die casting process, the metal is melted in the furnace and then injected into the dies in the die casting machine. Through the use of reusable dies, it can produce metal parts with complicated geometry. Die casting is one of the most common ways of casting; it has a high precision and is very efficient, while its cost is high. [12]
Figure 5 Die casting [14]
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Joined by welding: During welding, lead is melted and then solidified to connect the parts. This type of fabrication can be divided into fusion processes and Solid phase processes.
Fusion processes-the lead to be joined are cleaned and heated at first.
Placing the melted lead together into a pool, a filler rod is always used to add lead to the joint. [7]
Figure 2 Fusion welding process [9]
Solid phase processes-the lead to be joined are heated instead of being melted. First of all, loads are added to slid the parts together, creating friction. Then, the lead is softened and surface contaminations are removed. When the sliding is stopped, the normal load will be increased and the two parts will be joined together. [7]
Figure 2 Solid phase welding process [10]
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Reference:
[1] N.A., (2019), How lead is made, Retrieved from http://www.madehow.com/Volume-2/Lead.html, Accessed on [29/04/2019]
[2] Lead, CES Edupack
[3]: Swanton Welding. Swanton Welding. Retrieved from: https://swantonweld.com/hot-rolled-steel-vs-cold-rolled-steel/ Accessed on [May 08, 2019]
[4]: (April 29, 2019) Hot Rolled vs Cold Rolled Steel. Reliance Foundry Co. Ltd. Retrieved from: https://www.reliance-foundry.com/blog/hot-vs-cold-rolled-steel Accessed on [May 08, 2019]
[5] (January 21, 2019) Cold Rolling - process overview. Engineering Clicks. Retrieved from: https://www.engineeringclicks.com/cold-rolling/ Accessed on [May 17, 2019]
[6]: Cold Rolling. engineering fundamentals. Retrieved from: http://www.efunda.com/processes/metal_processing/cold_rolling.cfm Accessed on [May 08, 2019]
[7]: What is the Welding Process? - Definition from Corrosionpedia.
Corrosionpedia. Retrieved from: https://www.corrosionpedia.com/definition/1173/welding-process Accessed on [May 08, 2019]
[8]: Picture of hot and cold rolling. Available at: https://techminy.com/wp-content/uploads/2016/11/Hot-roll-and-cold-rolled-process.jpg Accessed on [May 17, 2019]
[9]: Picture of Fusion welding process. Available at: https://www.neimagazine.com/uploads/newsarticle/4363560/images/458584/large/friction-stir-welding%20b.jpg Accessed on [May 17, 2019]
[10]: Picture of solid phase welding process. Available at: https://str.llnl.gov/str/November01/gifs/Elmer1.jpg Accessed on [May 17, 2019]
[11] hot-vs-cold-metal-stamping, (2018), Brian Reed, Retrieved from https://www.fairlawntool.com/blog/hot-vs-cold-metal-stamping/, Accessed on [02/02/2019]
[12] Gravita, (2012), LEAD ALLOYING, Retrieved from http://gravitagroup.com/Lead-Alloying.asp, Accessed on [01/05/2019]
[13]vellerino SDI, (2018), Retrieved from https://vellerino-sdi.com/sec/frio/en/cold-stamping.html, Accessed on [03/05/2019]
[14]OZAY, (2019), Retrieved from http://www.oz-ay.com.tr/EN/22/3/Useful-Information.htm, Accessed on [05/05/2019]