WHAT IS ARC WELDING? Arc Welding is the processes of joining metal together thru fusion which is done by the

electric Arc, by electrical current (Arc 1994). The most widely used type of Arc welding isShielded Metal Arc Welding or stick welding (Repp1994). The arc reaches temperaturesof around 6,000 degrees Celsius which is concentrated at the tip of the electrode(Weldwell 2003).

The electrodes have a metal core surround by flux, which melts with the work piececreating a fusion weld. The flux coating forms a gas and slag that shields the moltingmetal pool.

This flux material is cleaned off once the weld has cooled with a wire brush. The weldshould be as strong or stronger then the metal that it is fusing together. Shielded MetalArc Welding is one of the most commonly used types of welding (Repp 1994). This isbecause it is one of the easiest, and the equipment is inexpensive. The ease of portabilitybecause it is one of the easiest, and the equipment is inexpensive. The ease of portabilitymakes them very good for mobile welding.

Arc Welding Equipmenthe equipment used in arc welding are as follows:

Welding machine as a converter to adjust the welding voltageand current.

Electrode holder is insulated and used to hold the electrode.

Electrode is a metal rod with a layer of coating which is used to Electrode is a metal rod with a layer of coating which is used toallow the flow of electric current to form the electric arc.

Earthing which connects the base metal and the weldingmachine power supply to prevent electric shock.

Electrode cable is an electrical connection between the electrodeholder and power supply.The cable is insulated with rubber.

Cleaning tools are used to chip and clean the traces of metalspatters and slag produced on the surface of the welded metal.

Figure :Arc welding joint principle

Electric arc welding carried out by the flow of electricity from the electrodes onElectric arc welding carried out by the flow of electricity from the electrodes onthe base metal and convert electrical energy into heat energy . Heat energy isthe base metal and convert electrical energy into heat energy . Heat energy isused to melt the electrode metal, additional metal or metal connectors areused to melt the electrode metal, additional metal or metal connectors arefinally done; producing a welded connection. Basically, the more electricity isfinally done; producing a welded connection. Basically, the more electricity isneeded to reach a certain temperature to melt the metal in the short term.needed to reach a certain temperature to melt the metal in the short term.Electricity supply from TNB is not suitable for welding works and does not haveElectricity supply from TNB is not suitable for welding works and does not havean impact. Sometimes we use the power transformer to convert electricityan impact. Sometimes we use the power transformer to convert electricitysupply to the electric current are suitable for use in welding practice. Here aresupply to the electric current are suitable for use in welding practice. Here aretwo common types of electrical current used in welding work.two common types of electrical current used in welding work.

Alternating current (Alternating current (a.ca.c.). A type of current that changed direction several.). A type of current that changed direction severaltimes in the flow of current. Alternating current is used to alter the strength andtimes in the flow of current. Alternating current is used to alter the strength anddirection 120 times within an hour or an alternating movement within 1 / 60direction 120 times within an hour or an alternating movement within 1 / 60second. This current frequency of 60 hertz said. In other words, alternatingsecond. This current frequency of 60 hertz said. In other words, alternatingcurrent with a frequency of 60 hertz would alter the strength and direction 60current with a frequency of 60 hertz would alter the strength and direction 60times per second.times per second.

Direct current (Direct current (d.cd.c). A type of current that has a fixed direction of the flow.). A type of current that has a fixed direction of the flow.Remain in the current direction can only be changed by changing the cableRemain in the current direction can only be changed by changing the cableconnection is used.connection is used.

Principles of Arc Welding

An electrical arc occurswhen electrical current flowsfrom an electrode tip to thesurface of the metal to bewelded. This occurs whenthe current carryingelectrodes in contact withthe metal to be welded, andthere is voltage betweenthem. The incident resultedin a high heat in a clantouch base metals andconsequently part of theelectrode tip melt. The

Equipment and Accessories

Basic requirements for carrying out a welding supply electrons ¬ trick is toappropriate voltage and current. The required voltage is between 20-100volts while the current according ampere is between 100-1000. Thereforeclear that the power supply from TNB is not appropriate and safe to use forwelding work as too high. There are two types of arc welding machines.Namely:a) providing a direct current machine.b) machine that provides alternating current.

Direct Current Welding MachineThere are two ways to obtain thedirect current used in welding

Alternating current Welding MachineAlternating current supply for the weldingwork is possible from a transformer Here theelectrode tip melt. The

melting of the electrode tipled to the formation of finemetal balls which movedinto the puddles on the basemetal occurs through thearc. This is called transfer ofmetals.Sometimes a liquid metalthat occurs is covered by aprotective gases resultingfrom the melting of thechemical coating ofelectrodes and producedfrom the burning of theelectrode coating.

direct current used in weldingmachines of this type is the set ofgenerators and welding equipmentrouter.advantages(A) Can be used to impose both coreand non core electrode.(B) Welding produces a smoother andis useful for welding thin sheet metal.(C) More than safety.Disadvantages(A) the price is higher.(B) Periodic maintenance should becarried out on the type of generatingplant because there are moving parts.c) Interference-interference from'Arc blow'.

work is possible from a transformer Here themain electricity supply to the power of 230-250 volts down to a value of less than 100volts by the converters. This transformer hasa flow control regulator that allows theoperator to choose the appropriate value ofcurrent equal to the size of electrodes used.In terms of efficiency and convenience,alternating current equipment is superior.Advantages only(A) The price is cheaper.(B) A little maintenance is required or maynot be needed immediately. Thisis because there are no moving parts in thetransformer.(C) Not applicable 'arc blow'.(D) Can be used at any place.

Arc Welding MachineArc welding machine is a transformer where to change from a high voltage to lowvoltage but high current yield for the issue of the use of arc welding. Equipped with

the electrode cable and earth cable to the desk.

Basic components in an arc welding machineIs consists of:transformers

Earth cable wentcable went electrodes

The electrodePower supplyPower supply

There are five types of welding machines. Namely:

- Type 'rectifier (DC)- Type of transformer (AC) - a combination ofAC / DC- Type-driven engine. (petrol or diesel) - Type of electric motordrives. (power)

Type 'rectifier' (DC)Type 'rectifier' (DC)

Arc welding machine type 'rectifier' (successor) is used because it has two options of current flow,the reverse polarity direct current and direct current straight polarity. Positive source is connectedto the electrodes so it was the reverse polarity. Sources connected to the negative electrodepolarity, then it is straight. All types of welding work for most metals are well suited to this type ofmachine. For the construction works and maintenance of machines of this type is the right choice.

Weaknesses:- Generate 'spray arc' (arc blow)- arc is not so stable against the type of power- There is no option for the arc characteristics.

Types of alternating current.Types of alternating current.

Welding machines alternating current (AC) was used because it produces a more stable arc and noWelding machines alternating current (AC) was used because it produces a more stable arc and novalid 'arc spray' (arc blow) with the penetration of a simple and quiet.

Weaknesses:- welding of certain metals and a limited use.- Not all of the electrodes can be used.- Able to operate at high ampere

Types of joint / combined AC / DC.Types of joint / combined AC / DC.

This type of machine can use both types of flows. It is necessary when welding certain metals withcertain currents. Has the widespread use. Can be used on many types of steel and welding position.

Weaknesses:- the relatively high costs- Valid 'arc spray' on some connections.

Drive Type petrol engine / diesel (DC or alternating current).Drive Type petrol engine / diesel (DC or alternating current).

This machine can be used in areas with no electricity. Can supply eitherThis machine can be used in areas with no electricity. Can supply eitheralternating current or direct current.alternating current or direct current.

Weaknesses:Weaknesses:-- large capital and high maintenancelarge capital and high maintenance-- NoiseNoise-- High CapitalHigh Capital-- High maintenance costsHigh maintenance costs-- Shot of the arc (arc blow)Shot of the arc (arc blow)-- Requires fuel.Requires fuel.

Types ‘pacuan motor’Types ‘pacuan motor’

This type of arc welding machines to produce a direct current. Producing directThis type of arc welding machines to produce a direct current. Producing directcurrent two choices. That polarity direct and reverse polarity.current two choices. That polarity direct and reverse polarity.

Weaknesses:Weaknesses:-- There 'arc blow'.There 'arc blow'.-- its maintenance is high. It uses carbon beberusits maintenance is high. It uses carbon beberusand should be changed at regular intervalsand should be changed at regular intervals

Polarity Arc Welding MachinePolarity Arc Welding Machine

There are two types of polarity arc welding machine. Namely:There are two types of polarity arc welding machine. Namely:

-- Polarity Direct Current Back (cables installed on the source electrode positive)Polarity Direct Current Back (cables installed on the source electrode positive)-- Direct Current Straight Polarity (lektrod cables attached to a negative source)Direct Current Straight Polarity (lektrod cables attached to a negative source)

Characteristics of Polarity:Characteristics of Polarity:

Features of the polarity of the DC polarity is reversed:Features of the polarity of the DC polarity is reversed:Features of the polarity of the DC polarity is reversed:Features of the polarity of the DC polarity is reversed:

-- The liquidity elekrod faster.The liquidity elekrod faster.-- Transparency in the shallowTransparency in the shallow-- faster welding speeds are required.faster welding speeds are required.

Features of the polarity of direct current straight polarity is:Features of the polarity of direct current straight polarity is:

-- The liquidity of the slow electrodeThe liquidity of the slow electrode-- Transparency of theTransparency of the-- The speed of the medium.The speed of the medium.

Effects of arc distance, angle, arc and speed of the results of the welding arc.Effects of arc distance, angle, arc and speed of the results of the welding arc.

Arc distanceArc distance

Arc distance is the distance between the tip of the metal core with the surface electrodes.Where the arc is issued will be maintained at this distance. Arc distance is too high will causethe molding is beautiful and also a lack of transparency. Arc distance is between 5.0mm to6.0mm.

Arc AngleArc Angle

Tilt angle formed between the electrodes to the surface in the direction of the electrodebendakerja. The angle of the arc is not right will cause a ripple molding so elongated or ovaland make a way not beautiful moldings.

While scraping method, the electrodes in carek-carek on solid starting point as you scratchmatches. When the rising arc of the distance to be maintained as described above.

and make a way not beautiful moldings.

Arc SpeedArc Speed

Speed is the speed of movement of the arc electrode to move towards the end of the finishwelding. This speed is usually dependent on the liquidity of the electrodes.Weld too fast to make too fine moldings and high and low transparency.

When we started the beginning of arc welding in place should make it free of paint andmaterials that can impede the flow of electrical current. Rules adopted park is as if tappingsomething slowly and can be issued when the arc is an arc distance should be kept at adistance of 5.0mm to 6.0mm.

While scraping method, the electrodes in carek-carek on solid starting point as you scratchmatches. When the rising arc of the distance to be maintained as described above.

Spray arcSpray arc

situation wherethe rising arcbetween theelectrode tip andworkpiece shouldstray from thepath. Usually thesound emittedfrom the spray isquite strong and

Selection of aSelection of awelding machinewelding machineto be usedto be usedsubject to thesubject to thefollowing.following.

- Position Welding- Type of metal tobe welded- Type ofconnection design- The thickness of

Electrodes.Electrodes.

The electrode is functioning as ametal additive in the arc weldingwhich is coated with a mixture ofa flux which comprisesof some particular type and havedifferent functions whenwelding work done.

Electrode ProductionElectrode Productionquite strong andthe size of thenormal arc alsomay seem a littlelarge. Thishappenedprobably due toits stateEarth clip positionis inaccurate.

- The thickness ofthe metal

Electrode ProductionElectrode Production

Protective welding electrodes (SMAW)is a fusion of the electrode coatedconsumable (consumable), whichconsists of various types dependingon the type of metal core and thecoating content of the electrodes. Theprocess of coating of flux in two ways,namely how the extrusion (extrusion)and how to dunk (dipping).

The electrode is a core wire that is surrounded by a type of flux. The coremetal and the flux vary depending upon what type of application it is beingused for. The flux around the core metal is used for many differentreasons. One reason is to protect the molten metal from the atmosphericcontaminates and gases that surround it. The second reason is that it helpsto control the current to flow thou the electrode to the work piece. The thirdis that it helps remove oxygen from the welded metal with deoxidize. Thesematerial are used for varying applications from raising the tensile strength ofmaterial are used for varying applications from raising the tensile strength ofthe weld to de-oxidation. The core metal is also made of many differentmetals depend upon the applications it is going to be used for. Theelectrdes have a numbering system on them that look something like this"E6011". The "E" in the code stands for the Electrode. The "60" in the codestands for the tensile strength which is a minimum of 60,000psi. The "1" inthe code stands for the position the electrode is to be used in, the one in thiscase stands for all welding positions. The last number in the code "1" standsfor the welding current either AC or DC.

Type of Coating ElectrodesType of Coating Electrodes

Electrode coating mixture consisting of severalElectrode coating mixture consisting of severalmaterials depending on the features of IRRImaterials depending on the features of IRRI--useuseelectrodes. Among the materials are mixed in theelectrodes. Among the materials are mixed in theelectrode coating iselectrode coating is serbokserbok iron oxideiron oxide--titaniatitania, sodium, sodiumsilicate, potassium, asbestos,silicate, potassium, asbestos, ferroferro--manganese.manganese.Coating of the electrodes is divided into three:Coating of the electrodes is divided into three:

ThinThin--coating (not coated)coating (not coated)MediumMedium--coatingcoating--Coating thicknessCoating thickness

Function Coating ElectrodesFunction Coating Electrodes

Function is a coating on the electrodes:Function is a coating on the electrodes:

Electrodes are classified into sevenElectrodes are classified into sevengroups,groups, namely:

- Soft Steel- Steel 'low alloy'- Stainless steel- Hardening surface- Nickel and nickel pancalogam- Aluminum and aluminum pancalogam- Copper and copper pancalogam

‘SLAG’ function.‘SLAG’ function.

‘Slag’ is a membrane that is the result ofFunction is a coating on the electrodes:Function is a coating on the electrodes:

-- Producing gas masks.Producing gas masks.-- Generate ‘slag’ cap moldingGenerate ‘slag’ cap molding-- Stabilizing the arcStabilizing the arc-- Contains a mixture to use special features.Contains a mixture to use special features.

Coating of the electrodes can be categorized intoCoating of the electrodes can be categorized intotypes:types:

-- RutileRutile-- CelluloseCellulose-- Iron filingsIron filings

‘Slag’ is a membrane that is the result ofmelting molding surface coating of theelectrodes. The functions are:

- Protect the moldings from the outsideair during the cooling occurs.- float the dirt to the surface of themolten crater.- Control of molding so that uniform.- Slows down the rate of cooling toimprove the properties of metals- Providing mechanical protection to thetransfer of metal from the electrode intothe base metal.