Gtaw welding pdf

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Objectives continued Remove a contaminated tungsten end Melt the end of the tungsten electrode into the desired shape Compare water-cooled GTA welding torches to air-cooled torches The purpose of the three hoses connecting a water-cooled torch to the welding machine.

Objectives continued Choose an appropriate nozzle How to get an accurate reading on a flowmeter Compare the three types of welding current used for GTA welding Shielding gases used in the GTA welding process. An arc is established between a non-consumable tungsten electrode heating element and the base metal The inert gas provides the needed arc characteristics and protects the molten weld pool When Argon became plentiful, the GTA process became more common.

High tensile strength Hardness High melting temperature High boiling temperature Good electrical conductivity. Tungsten continued Tungsten is the best choice for a non consumable electrode High melting temperature Good electrical conductivity.

As the tungsten electrode becomes hot the arc between the electrode and the work stabilizes But a clean and correctly ground tungsten is needed. Good mechanical and electrical contact Use as low a current as possible Use a water-cooled torch Use as large a tungsten electrode as possible Use DCEN current Use as short an electrode extension as possible Use the proper shape electrode Use an alloyed tungsten electrode.

Tungsten continued The collet is the cone-shaped sleeve that holds the electrode in the torch Large-diameter electrodes conduct more current The current-carrying capacity at DCEN is about ten times greater than at DCEP The preferred electrode shape impacts the temperature and erosion of the tungsten With alternating current, the tip is subjected to more heat than with DCEN.

Figure The smooth surface of a centerless ground tungsten electrode. Courtesy of Larry Jeffus. Types of Tungsten Electrodes Pure tungsten is an excellent nonconsumable electrode Pure tungsten can be improved by adding:.

Grinding Often used to clean a contaminated tungsten or to point the end Should have a fine, hard stone A coarse grinding stone with result in more tungsten breakage. Should be used for grinding tungsten only Metal particles will quickly break free when the arc is started, causing contamination. Holding against a sharp corner and hitting results in a square break After breaking squarely, melt back the end. Chemical Cleaning and Pointing Tungsten can be cleaned and pointed using one of several compounds Heated by shorting it against the work Dipped in the compound When the tungsten is removed, cooled, and cleaned, the end will be tapered to a fine point The chemical compound will dissolve the tungsten, allowing the contamination to fall free.

Pointing and Remelting Tapered tungsten with a balled end is made by first grinding or chemically pointing The ball should be made large enough so that the color of the end stays dull red and bright red Increase ball size by applying more current Surface tension pulls the molten tungsten up onto the tapered end.

GTA welding torches are water- or air-cooled Water-cooled GTA welding torch is more efficient Water-cooled torch has three hoses connecting it to the welding machine Nozzle directs the shielding gas directly on the welding zone Flowmeter regulates the rate of gas flow.

High Freq. DC Component will take place if there is no High Freq. Shielding Gases continued Argon effectively shields welds in deep grooves in flat positions Helium offers the advantage of deeper penetration.

Shielding Gases continued Hot start allows a surge of welding current Preflow is the time gas flows to clear out air in the nozzle Some machines do not have preflow. Postflow is the time the gas continues flowing after the welding current has stopped. Shielding Gases continued Ionization Potential Amount of voltage needed to kick start the arc. The ionization potential, or ionization energy, of a gas atom is the energy required to strip it of an electron.

That is why a shielding gas such as helium, with only 2 electrons in its outer shell, requires more energy higher voltage parameters for welding. The ionization potential of a shielding gas also establishes how easily an arc will initiate and stabilize. A low ionization potential means the arc will start relatively easy and stabilize quite well. A high ionization potential has difficulty initiating and may have difficulty keeping the arc stable.

Objectives Applications using the gas tungsten arc welding process Effects on the weld of varying torch angles Why and how the filler rod is kept inside the protective zone of the shielding gas How tungsten contamination occurs and what to do Causes of change in welding amperage Correct settings for the minimum and maximum welding current.

Pada pengelasan GTAW ini elektroda atau tungsten ini hanya berfungsi sebagai penghasil busur listrik saat bersentuhan dengan benda kerja, sedangkan untuk logam pengisi adalah filler rod. Fungsi Las GTAW ini biasanya digunakan untuk melakukan pengelasan Aluminium atau stainless steel yang memang banyak membutuhkan perlakuan khusus.

Namun yang paling sering digunakan untuk mengelas adalah arus DC. Untuk penggunaannya biasanya DCEN digunakan untuk pengelasan yang membutuhkan penetrasi dalam seperti root pada sambungan V Joint. Welding Torch adalah alat yang digunakan sebagai pegangan saat proses pengelasan, dalam welding torch terdapat beberapa komponen seperti ceramic cup yang berfungsi sebagai tempat keluarnya gas pelindung. Kemudian tempat tungsten, penghantar arus listrik, slang gas pelindung.

Untuk detail gambarnya silahkan lihat gambar di bawah ini. Different specialty industries require the application of GTAW welds in a wide variety of sizes. In addition, different size GTAW welding machines , ranging from smaller portable units which draw a minimum of 8 kW to large industrial scale GTAW models which require a full 30 kw of power will be amongst your work tools at many job sites where this extremely strong, clean GTAW welding method is used.

These welding systems can also be altered to function properly with the use of a portable engine power source, such as a powerful generator or other portable and powerful energy source. Whether you have just graduated high school , recently completed military service , or are considering a GED program in preparation to enter a skilled trade training course, talking with a representative at Tulsa Welding School can help you gain clarity and focus in regards to making an important career move.

Give us a call today to learn more about the programs available to young adults in the Tulsa, Jacksonville, and Houston areas! Subscribe to our blog via the form to the right. Apply Now Request Info.