Welding technique electric current

SMAW welding is a technique by using an electric current flow and arc-shaped electrode webbed. Other types of arc welding with an electric current is SAW submerged arc welding, gas metal arc welding GMAW-MIG, gas tungsten arc welding and plasma arc G. This Occurs in the SMAW welding electrode gas when it melts wrap membrane, so the process is not required pressure / pressure inert gas to displace the oxygen or water can cause corrosion or bubbles in the weld-weld. Prose welding Occurs Because the electric current flowing Between the electrodes and welding material forming the heat so it can reach 3000 ° C, Thus Spake making the electrode and the material to be welded to melt. Based on its current type, welding is Divided into AC and DC current, the which flows straight polarity DC-Divided into direct and reverse polarity polarity - polarity reversed. Welding machine was Divided into two types, namely constant current - constant voltage and current fixed - fixed voltage, which in any arc welding electric current in the event of an enlarged bow will lower and raise the voltage and current in the shortened arc current will increase of and Decrease voltage.


To get a good weld should:

1. Appropriate electrodes using
2. Appropriate type of current
3. Type of polarity is correct for the DC current
4. Avoid left-right movement during welding welding
5. Short form of the arc current, welding doing a steady and regular
6. The rate of welding electrodes in accordance with the speed of the melt.

Often the problems That Arise in the arc welding current is:

1. Electrode freezes / stops welding
2. Form an ugly seam welding
3. Arc welding current is bad Because It expands
4. Moderate membrane electrode / flux is made Generally dariserat
5. Wood / cellulose
6. Titanium oxide
7. + Titanium base compound
8. Mn + Fe + Si
9. Iron oxide
10. CaCO3, the which will form the type of electrode in the form type: E, R, ER, EC, EW, B, RB, RG and F.

Selection of electrodes is based on:

1. Properties of the materials to be welded
2. Welding position
3. Connection type
4. Number of welding
5. Density of the welding connection
6. Current types are available.

AC welding machine
Electrical machinery classified AC DC welding machines and welding machine, welding machine, air conditioning is usually a welding transformer, welding machines DC while besides transformers equipped with a diode rectifier or (Changer alternating current into direct current) motor drive Typically uses either diesel or petrol motors and electric motors. That AC welding machine uses a transformer or welding transformer.

Currently Widely used welding machines DC Because DC has
some of the advantages of the AC welding machine, Such as arc stability,
polarity can be set.

Welding DCSP (Direct Current Straight Polarity) or welding Straight Polarity.
If the base material or the material to be welded is connected to the positive pole (+) and the electrode connected with negative polarity (-) on the DC welding machine in this way is called straight polarity welding or DCSP.

In this way the electric arc moves from the electrode to the base material so That the collision of electrons in the base material resulting in 2/3 heat in the base material and the third heat in the electrode. This method will result in melting of the base material so That more than the electrode results have deep penetration welding, so That both are used in welding a slow and narrow weld bead and for a thick plate. Welding DCRP (Direct Current Reversed Polarity) Welding or reverse polarity. With the welding process in this way connected with the base material of negative polarity (-) and the electrode connected with the positive pole (+) of DC welding machine, and so-called DCRP arc moves from the electrode base material and the electron collision resulting in electrode 2/3 heat at the electrode and the third heat in the base material.

This method will Produce more That so the melting electrode has a shallow penetration welds, and both are used in welding of thin plates with the weld bead width.

Welding AC (alternating current) or alternating current to alternating current electric welding there is no positive and negative poles (two both the same) and therefore the connection behind the inverted REMAIN the same results. Each pole will receive 50% of heat penetration and consequently normal.

Electrode welding
Most of the SMAW welding electrode coated by a layer of flux, the which serves as a gas-forming fluid That Protects the metal from the surrounding water Contamination. In Addition fluk also useful for forming weld slag That also serve to protect the weld from the air surrounding liquid. Electrode layer is a mixture of chemicals That the composition as needed welding. According to the AWS (American Welding Society) electrodes are classified with the letter E and Followed by four or five digit Following E. The first two digits or three digits indicate tensile strength welds three digits indicate
over 100 000 psi tensile strength while the two digits indicate the weld tensile strength of less than 100 000 psi. For example, electrode E 6013 has a tensile strength of 60.000 psi (42 Kg/mm2). While the third or fourth digit figure for a Greater tensile strength 100 000 psi (70 Kg/mm2) next digit position of the welding point, if the numbers mean for all positions. Welding 1, number 2 means the weld flat horizontal or l and 3 show for the welding flat. The last digit indicates the type of chemical mixture of the electrode layer.

Electrode welding mild steel & alloy

Here is given a list of conditions for mild steel welding electrodes and low alloy steels Philips.

Electrodes for Cast Iron Fitting
Electrode used for welding cast iron is as follows:

Steel electrodes
Electrodes of this type when used for welding cast iron will Produce a strong weld deposit so it can not be machined. Thus Spake the electrode is used when the welding is not done anymore. To weld cast iron with steel electrodes can be used AC or DC welding plane poles reversed.


Nickel electrode
This type of electrode used for welding cast iron, when the welding is done again with the machine. Nickel electrode can be used in the sense of seeing the welding position. Ridge welding electrodes are produced in cast iron is flat and smooth when used in DC welding plane poles reversed. Characteristics of the nickel electrode can be seen in the table below.

Bronze electrodes
Welds by means of electrodes are resistant to cracking, so the length of the weld can be added. Core wire of the electrode is made of phosphor bronze and given a membrane That Produces a stable arc.

Electrodes for Aluminum.
Aluminum can be welded with electrodes made electricity from the same metal. The selection of aluminum electrode in accordance with the work table is based on information from the which the factory makes. Aluminum electrodes AWS-ASTM AI-43 for electric arc welding is a welding plane pole upside down where the use of DC currents expressed in the following table

Membrane Electrodes for Hard
Objectives in terms of hard coatings are conditions for use of equipment or materials are resistant to scraping That, punch and wear resistant. For this purpose the electrodes for hard coatings can be classified into three types are:

Scraping the electrode resistance.
Electrodes of this type are made of chrome carbide tube filled with carbide Filings. Electrodes with a diameter of 3:25 mm - 6.5 mm is used bicycles AC or DC welding plane poles reversed.
These electrodes can be used for hard coatings on the surface of a thin slice, expand the holes and some type of knife.

Electrode resistance blows.
These electrodes can be used on AC or DC welding plane poles reversed. Hard coatings used for the solver and a hammer.

Wear-resistant electrode.
These electrodes are made of non-ferrous alloys containing Cobalt, Wolfram and chrome. Usually used for hard surface coatings and the exhaust valve and valve seat wear in the which the temperature is very high.

ARC Welding Machine Electrode

Electric arc welding electrode is encased in one of the electrical arc welding electrode feed, the the which uses an electric arc as a source of heat. The heat That Occurs in electric arc occurring Between the electrode with the workpiece, melting the tip electrode (wire) welding employment and local bodies, then form an alloy, solidifies into welds (weld metal). Wrap (which serves as an electrode flux coating will burn in time process, and the gas Occurs That will protect the process to the influence of outside water. Fluid will wrap on the surface of the weld solidifies and floats called slag, the the which can then be cleaned easily.

WELDING MACHINE (WELDING MACHINE).
Requirements of the SMAW process is a continuous supply of the electric current (electric current), the number of ampere and voltage stability of the welding flame is quite good (Arc) will REMAIN intact.

Where electric power (electric power) obtained from the welding machine by type currents are issued 3 (three) types of machines namely:
a. Machine with direct current (DC).
b. Machine with an alternating current (AC)
c. Machine with a combination of the direct current (DC) and alternating
(AC)
Machine on direct current (DC) equipped with the changing nature of alternating current component (AC) into direct current (DC) is a generator, Because That Is the electric current used here not from the battery, but the emergency power generator.

Alternating current machines do not need to be equipped with a generator, a transformer, but enough. Electric characteristics 80-85% efficiency. For a combination of AC and DC machine is equipped with a transformer and rectifier, the rectifier is the which has a function to smooth the flow.

Selection of Welding Parameters
The length of the arc (Arc Length) is Considered to be either more or less the same with him. electrode is used. Magnitude of the voltage used for welding every position not the same. For example he was. electrode 3 mm - 6 mm, has a voltage of 20-30 volts in flat position, and this voltage will be reduced Between 2-5 volts at a position above the head. Voltage stability is greatly Determines the quality of welding and also stability through sound during welding. The amount can be heard also affect welding current, wherein the amount of electrical current depending on the welding of the material and size of welds, the geometry of the welding connection, and he's kind of electrode. core electrode. For welding in the weld area has high absorption capacity That Necessary heat and large electric currents may also need additional heat. Moderate for steel welding alloys, the the which can be easily hardened his HAZ region too fast cooling effect, cooling it to withstand these high heat input is given to a large welding current. Welding of metal alloys, in order to avoid burning the element should be used alloying elements welding current is as small as possible. Also on the hot weld cracking may occur, for example, in austenitic stainless steel weld the use of heat so it cultivated as small as possible must small. Welding speed of the welding current depends on the parent material, type of electrode, he. Core electrode, the geometry of the connection, the connection accuracy. Necessary in order to more higher welding currents can Quickly.

Electrical polarity affect the outcome of an electric arc. Electric Properties on the arc direct current (DC) will be more stable than the alternating current (AC). There are two types of polarity is the polarity of the straight, where the object of positive and negative working electrode (DCEN). Reverse polarity is the reverse polarity ie the opposite. Characteristics of metal removal Occurs by ejection, then this polarity mepunyai more results in the than welding with straight polarity (DCEN).

Welding Implementation
Ignition of the arc welding can be done by performing a brief relationship with the parent metal electrode tip, and then separate them again until a Certain distance as the length of the arc. Where the normal arc length Between the the which is 1.6 - 3.2 mm.

Electric arc outages done by removing the electrode from the parent material. to Produce a weld bead connecting the well can be performed as follows:
Before the electrodes should be kept away from the parent metal arc length reduced first, then the electrode was kept in a position to more adequately tilted.

Movement of Welding Electrode
There are different Airways to stimulate the (swinging) welding electrode, namely:

1. Electrode is driven by forward and backward, this method is one form of weaving methods.
2. Other forms of weaving is to make a move like and a half months.
3. Electrode That resembles a figure 8 motion.
4. Electrode with a rotating motion.
5. Electrode movement by forming hesitation.

All movements have a purpose to get a deposit weld metal with a flat surface, smooth and protected from the notch and Including slag, slag, the most Important in the movement of the electrode is the precision of angle and speed stability. Swing-shaped electrode for welding or bending webbing width of weld bead welding is limited to 3 (three) times as large as the diameter of the electrode.

Welding Techniques for Groove Connection Type

Flat position (1G)
It is recommended to use methods Such as figure 9 A and B. This can be done to kind of connection penetration on both sides, but can also be done on one side only penetration. Type a flat position (1G) in the implementation very easy. Pipe material may be applied on the road playing the pipes.

Horizontal position (2G
2G welding pipe welding positions are horizontal, upright position to the pipe and welding Carried horizontally around the pipe. Difficulty horizontal position welding is the weight of the liquid weld itself it will always be down. The angular position of the 2G pipe welding electrodes is 90 º. The length of the electrode movement Between 1-2 times the diameter of the electrode. When too long can lead to lack of good quality weld. Arc length in
short as possible try ½ times the diameter of the welding electrode. For the welding of filling made with a circular motion and Attempted to burn well on both sides of the seam so as not to occur ACAT. This movement is repeated for the next replenishment.

Vertical position (3G)
3G position welding done on the plate material. 3G is Implemented on a vertical position and the electrode plate. Difficulty of welding is similar to the 2G position due to the gravitational force of the liquid electrode welding.

Pipe welding in 5G position welding can be Divided into up
and welding down. Welding up is usually performed on the pipe wall has a high thermal Because It requires a teal. Speed ​​up the welding direction to the direction of welding is lower than down, so the heat input per unit area is higher than the 5G welding pipe welding down. The position placed on a fixed horizontal position and the welding done around the pipe. So That the welding
well, it is Necessary to weld studs (tack weld) on 5-8-11 and 2 o'clock position. Start welding at 5:30 to 12:00 hours through 6 hours and then Followed by the 5:30 o'clock position at 12:00 over 3 hours

Movement of the electrode to pass root position (weld root) is regular at a distance triangles ½ times the diameter of the electrode arc.

Welding down
Usually done on a thin pipe and oil pipelines and natural gas. The reason the use of welding down more lucrative dikarenakanlebih faster and more economical.