According to its history, the practice of grafting has been known to humans about 3,000 years ago, such as: welding, soldering, forging and brasing. But it was only in 1903, Thomas Edison patened patents for electrolytic deposition of nickel between plates heated in a hydrogen environment.
In general there is a lot of understanding of welding, but we just "interested" to two (2) understanding only.
First; Welding is a process of joining metal, where the metal becomes one due to heat, with or without pressure.
Second; Welding is a metallurgical bond brought about by the attractive force (cohesive force) between the metal atoms it.
So that welding can be done well, then all the two metal surfaces need to be free of adsorbed gas or oxides.
11.1. TYPES OF CONNECTIONS WELDED
In general, the types of the welded joints can be grouped into 2 (two) ;
a). Cold welding
When two surfaces clean, flat surface in the press, then the crystals it will be depressed as well and intersect, and when the pressure in the view, then the area allusion was also increase in size (area), In this case, the oxide layer of her broken and the metal is deformed , so that the crystals in both surface and eventually will merge any two metals together.
b). welding Heat
When both surfaces are flat and clean, besides pressed too heated, it will blend into the surface, so that there was hot welding connection. The higher its temperature welding, to metal uletan would grow and atomic diffusion process will be accelerated.
Even the hot junction with the pressure more efficiently, but its connection strength is determined by the bonds between its atoms.
11.2. TYPES OF WELDING PROCESS
There are many kinds and types of welding are known and developed, depending on the method of heating and its equipment. However, the following will explain the types of welding which is more common and is often used in the industrial and commercial world.
Welding-welding are:
1. Welding Patri, consisting of:
a). flame
b). kitchen
c). induction
d). custody
e). dye
f). infrared
2. Welding Forging, consisting of:
a). done by hand
b). to be machined:. roller
, o'clock and die
3. Gas Welding, consisting of:
a). Air + acetylene
b). oksiasetilen
c). oksihidrogen
d). pressure
4. Welding Prisoners, consisting of:
a). point
b). hem
c). projection
d). blunt
e). flame
f). percussion
5. Induction Welding, consisting of:
- High frequency
6. Arc Welding, consisting of:
a). Carbon Electrodes:. protected and without shielded
b). Eletroda Metals: • Shielded:. arc telindung
, point arc
, hydrogen atom
, inert gas
, submerged arc
, piston
, electro slag
• Shielded Tanta: .logam plain and lantak
7. Electron Beam
8. Welding Lasser
9. Friction Welding
10. Thermite Welding, consisting of:
a). pressure
b). unstressed
11. Welding Flow
12. Cold Welding, consisting of:
a). pressure
b). ultra sonic
13. Welding letup
To unite or connect metal on the welding process, sometimes requiring rolling or suppression and beatings, in another process, need to melt metal and does not require pressure. In the welding process with the pressure, his common metal surfaces must dipanas the first, resulting in force cohesion. Heating temperature must remain below the melting point of the parent metal, even if until melted, then the molten metal to be in localization, here takes another additional liquid metal (filler).
Sometimes, the metal melts and then freezes, there will be trapped oxide, this is a big loss. For that is often used to dissolve the oxide flux in the slag which then float on the surface of molten metal. Oxide is above this level, can serve to protect the base metal from the outside air contamination.
Since the events of oxidation can take place so very quickly at high temperatures, the velocity factor of the welding process, it needs attention.
In the welding process, it is always recommended that the parent metal surfaces to be welded must be clean, because the surface is clean, will produce welded joints are much stronger.
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