DCV 1044 – AMALAN BENGKEL

TOPIK 4: KIMPALAN

Disusun oleh:Muhammad Amirul bin Abdullah

Unit Automotif, KKBD

cikguamirul.wordpress.com

TOPIK 4.0 KIMPALAN

3.1 MENJELASKAN PROSES KIMPALAN ARKA

3.2 MENJELASKAN PROSES KIMPALAN GAS

3.3 MENJELASKAN PROSES KIMPALAN MIG

3.1

MENJELASKAN PROSES KIMPALAN ARKA

• Arc Welding or SMAW (Shielded Metal Arc Welding):

Arc welding is also called as Shielded Metal Arc welding, orsimply referred to as ‘Stick’. This is the most basic of allwelding types. The welding stick uses electric current to forman electric arc between the stick and the metals to be joined.To weld iron and steel, this type of welding is often used inthe construction of steel structures and in industrialfabrication. Stick welding can be used for manufacturing,construction and repair work.

How to Arc Weld

• Shielded Metal Arc welding is the process of joining two metal pieces using a flux covered electrode which is melted in an electric arc and becomes a fused part of the pieces being welded. This article will describe the use of flux-coated welding rods and a simple, transformer type cracker box welding machine.

Source: https://www.wikihow.com/Arc-Weld

Steps 1: Understand the process of shielded Metal Arc Welding

• An electric arc is formed at the tip of the welding rod when a current passes across an air gap and continues through the grounded metal which is being welded. Here are some of the terms and their descriptions used in this article:

• Welding machine. This is the term used todescribe the machine which converts 120-240volt AC electricity to welding voltage, typically 40-70 volts AC, but also a range of DC voltages. Itgenerally consists of a large, heavy transformer, avoltage regulator circuit, an internal cooling fan,and an amperage range selector.The term welderapplies to the person doing the welding. Awelding machine requires a welder to operate it.

• Leads, or Welding leads. These are the insulated copper conductors which carry the high amperage, low voltage electricity to the work piece that is being welded.

• Rod holder, or stinger is the device on the end of the lead that holds the electrode, which the person welding uses to accomplish the welding task.

• Ground and ground clamp. This is the lead that grounds, or completes the electrical circuit, and specifically, the clamp that is attached to the work to allow the electricity to pass through the metal being welded.

• Amperage, or amps. This is an electrical term, used to describe the electrical current supplied to the electrode.

• DC and reverse polarity. This is a different configuration used in welding with an arc/electrode system, which offers more versatility, especially in overhead welding applications and for use welding certain alloys that do not weld easily with AC voltages. The welding machine that produces this current has a rectifier circuit or has the current supplied by a generator, and is much more expensive than a typical AC welder.

• Electrodes. There are many specialized welding electrodes, used for specific alloys and types of metals, such as cast or malleable iron, stainless or chromolysteel, aluminum, and tempered or high carbon steels. A typical electrode consists of the wire rod in the center covered with a special coating (flux)which burns as the arc is maintained, consuming oxygen and producing carbon dioxide in the weld area to prevent the base metal from oxidizing or burning away in the arc flame during the welding process.

Here are some common electrodes and their uses:

• E6011 electrodes are a mild steel electrode with a cellulose fiber coating. The first two numbers in the electrode identification is the tensile strength, measured in pounds per square inch times 1,000. Here, the yield of the electrode would be 60,000 PSI.

• E6010 electrodes are a reverse polarity electrode, commonly used for welding steam and water pipes, and are particularly useful for overheadwelding, since the metal holds its position while in a liquid state, being drawn into the molten weld pool by the flow of the direct current from the electrode to the workpiece.

• Other specific purpose E60XX electrodes are available, but since E6011s are considered a standard, general purpose rod, and E6010s are considered the standard for reverse polarity DC welding, they will not be covered in detail in this article.

• E7018 electrodes are low hydrogenflux coated steel rods, with a high yield tensile strength of 70,000 PSI. These are often used in assembling structural steel used in the construction industry, and in other applications where a strong filler material and higher strength weld is required. Note that, although these rods provide greater strength, they are less forgiving in respect to achieving a clean, high-grade weld at incorrect amperages and with dirty (rusted, painted, or galvanized) steels. These electrodes are called low hydrogen due to every attempt to lower the hydrogen content. These electrodes must be stored in an oven with a temperature between 250ºF and 300ºF. This temperature is above the water boiling point of 212ºF at sea level. This temperature keeps the moisture (dew)(H2O) in the air from collecting in the flux.

• Nickel, Castalloy, Ni-Rod electrodes. These are special rods made for welding cast, ductile, or malleable iron, and have more yield, to allow for the expansion and contraction of the iron material being welded.

• Dissimilar metals rods. These rods are made from a special alloy and give better results when welding tempered, hardened or alloyed steels.

• Aluminum rods. These are a more recent technology andallow arc welding aluminum with a conventional welder,rather than using a special gas-shielded wire feed welderlike a MIG (metal, inert gas) or TIG(tungsten, inert gas)welding machine, often referred to as heliarc welding, sincehelium was the gas used to shield the arc flame whilewelding. The official names created by the AmericanWelding Society (AWS)for this arc type welding are ShieldedMetal Arc Welding (stick), Gas Tungsten Arc Welding(tig)and Gas Metal Arc Welding (mig).

• Electrode sizes. Electrodes come in a variety of sizes, measured by the diameter of the metal center of each rod. For mild steel rods, a diameter range of 1⁄16 inch (0.2 cm) to 3⁄8 inch (1.0 cm) is available, and the size used is determined by the amperage of the welder, and the thickness of the material being welded. Each rod performs best at a given amperage range. Selecting the correct amperage range for a given size rod will depend on the base material and the desired penetration, so specific amperages will only be covered for the welding described further in this note.

Safety equipment

• A critical part of welding safely is having, and knowing how to use, the correct safety equipment for the job. Here are some typical items that are required for welding safely.

• Welding shield (hood). This is the mask which is worn to protect the person welding from the bright flash of the arc, and from sparks being thrown during welding. Standard arc welding lenses are tinted very darkly, since exposure to the arc flash can cause flash burns to the retina of the eye. A level 10 darkness is the minimum for arc welding. Welding hoods with a flip up lens was once preferred, as the dark lens can be lifted up, and a separate clear glass lens will protect the welder from bits of slag while the weld is chipped. The newer self darkening welding shields are the most desirable welding shield now sold. These welding shield lens are very light colored for grinding and torch cutting. When an arc is struck the automatic self darkening lens will change to a preset #10 shade. Even newer on the market are the variable shade automatic self darkening lens.

• Welding gloves. These are special, insulated leather gloves that reach about 6 inches (15.2 cm) above the wrists, and protect the hands and lower arms of the welder (the person welding). They also provide limited protection from accidental shock if the person welding comes into contact with the electrode accidentally.

• Welding leathers. This is an apron like leather jacket that covers the shoulders and chest of the welder, used for overhead work where sparks might ignite the welder's clothing, or cause burns.

• Work boots. The person welding should wear at least a 6 inch (15.2 cm) lace-up type boot to prevent sparks and hot slag from burning his feet. These boots should have insulating soles made from a material which does not melt or burn easily.

Steps 2: Learn the steps for creating a successful weld

• Welding is more than dragging a welding rodacross a piece of steel and gluing it to anotherone. The process begins with properly fitting andsecuring the work pieces, or metal to be welded,together. For thicker pieces, you may want togrind a bevel so subsequent beads can be placedin the groove to fill it completely with a solidweld. Here are the basic steps for completing asimple weld.

• Strike the arc. This is the process of creating an electricarc between the electrode and the workpiece. If theelectrode simply allows the current to pass directly intothe grounded work piece, there will not be enoughheat produced to melt and fuse metal together.

• Move the arc to create a bead. The bead is the metalfrom the melting electrode flowing together withmolten metal from the base metal to fill the spacebetween the pieces being joined by welding.

• Shape the weld bead. This is done by weaving the arc backand forth across the weld path either in a zig zag or figure 8motion so the metal spreads to the width that you wantyour finished weld bead to be.

• Chip and brush the weld between passes. Each time youcomplete a pass, or trip from one end to the other of yourweld, you need to remove the slag, or the melted electrodeflux material, from the surface of the weld bead so onlyclean molten metal will be filling the weld on thesubsequent pass.

Steps 3: Gather the tools and materials you will need to begin welding.

This means the welding

machine, electrodes,

cables and clamps, and the metal to be welded.

Steps 4: Set up a safe work area, preferably

with a table constructed of steel or other non-flammable material.

For practice, a few

pieces of mild steel, at

least 3⁄16 inch (0.5 cm) thick will work.

Steps 5: Prepare the metal to be weldedIf the metal consists of two pieces that

are to be joined in the welding process,

you may need to prep, or weld

prep them, by grinding a beveled edge

on the sides that are to be joined. This

allows for sufficient penetration of the

weld arc to melt both sides to a molten

state so the filler metal bonds through

the sectional thickness of the metal. At

the least, you should remove any paint,

grease, rust, or other contaminants so

you are working with a clean pool of molten metal as you weld.

Steps 6: Attach clamps to hold your metal pieces together, if need.

Locking type pliers,

"C" clamps, a vice,

or spring loader

clamps will usually

work. For special

projects, you may

find you will have to

adapt different

techniques to secure

the work pieces until they are joined.

Steps 7: Attach the ground clamp to the larger piece of stock that is being welded.

Make sure there is a

clean location so that the

electrical circuit can be

completed with minimal

resistance at the ground

location. Again, rust or

paint will interfere with

the grounding of your

work piece, making it

difficult to create an arc when you begin welding.

Steps 8: Select the correct rod and amperage range for the work you are attempting.

1. As an example, 1⁄4 inch

(0.6 cm) plate steel can be

welded effectively using an

E6011, 1⁄8inch (0.3 cm)

electrode, at between 80-100

amps. Place the electrode in

the electrode holder

(henceforth referred to as

the stinger) making sure the

conductive material of the

stinger clamp is on the clean

metal at the end of the

electrode.

Steps 9: Turn on your welding machine.You should hear a humming

sound from the transformer.

The sound of the cooling fan

running may or may not be

heard. Some welding machine

fans only operate when the

machine requires cooling. If

you do not, you may need to

check the circuit that is

supplying your power, and the

breakers in the panel box.

Welding machines require a

considerable amount of power

to operate, often a special

circuit rated at 60 amps or

more at 240 volts.

Steps 10: Hold the stinger in your dominant hand by the insulated handle, with the rod in a position so that striking the tip of it against the plate you are welding

will be as natural a movement as possible.

Hold your welding shield up just high enough soyou can see to move the electrode to within a fewinches of the workpiece, ready to flip in down toprotect your eyes. You may want to practice tappingthe electrode against the weld metal to get the feelof it before turning the power on, but never strikean electric arc without protecting your eyes.

Steps 11: Select the point where you wish to begin your weld.

• Position the tip of the rod close to it, then drop the welding hood into place. You want to tap the tip of the electrode against the metal to complete the electrical circuit, then instantaneously pull it back a little bit, to create an electric arc between the electrode tip and the metal being welded. Another way to strike an arc is like striking a match. This arc gap, or airspace, creates a great deal of resistance in the electrical circuit, which is what produces the arc flame or plasma and heat needed to liquefy the electrode and the metal adjacent to the weld area.

Steps 12: Strike the electrode against the surface of the metal, pulling it back slightly

when you see an electric arc occur

• This takes a great deal of practice, since different electrode diameters and welding amperages require a different gap between the tip of the electrode and the work piece, but if you can hold the gap steady, a continuous electric arc will occur from the electrode to the work piece. Typically, the arc gap should be no greater than the electrode diameter. Practice steadying the arc by holding the electrode about 1/8 to 3/16 of an inch from the work piece, then begin moving along the path you want to weld. As you move the electrode, the metal will be melting away, filling the pool of molten metal and building your weld.

Steps 13: Practice traveling across the path of your weld with the electrode until you can keep a consistent arc, moving at a consistent speed, and in line with the path you want to weld.

• When you have mastered controlling the arc, you will begin to practice laying, or building up the weld bead. This is the deposit of metal that joins the two pieces that you are welding together. The technique you use for laying your bead will depend on the width of the gap (if there is one) you are filling, and the depth you want the weld bead to penetrate. The slower you move the electrode, the deeper the weld will go into the metal work pieces, and for making a wide path, the more you zig zag or weave the electrode's tip, the wider the bead you will lay up.

Steps 14: Keep the arc established as you move along the weld you are making.

• If the electrode grounds to the metal and becomes stuck, jerk the stinger to break the rod free either from the stinger clamp or the weld metal. If the arc is lost because you move the electrode too far from the metal's surface, stop the process and clean the slag from the spot you are welding so when you re-strike the arc to continue, there will be no slag in the weld area to contaminate the new weld you are beginning from the place the arc was lost or broken. Never lay a new bead over existing slag, as this material will melt in the arc plasma and bubble through the new layer of metal you are placing, resulting in a weak and dirty weld.

Steps 15: Practice moving the electrode in a sweeping motion to create a wider bead.

• This will allow you to fill more of the weld in a single pass, leaving a cleaner and more sound weld. The electrode is moved in a sideways motion as it is drawn along the weld path, either in a zig-zag, curved, or figure eight motion.

Steps 16: Adjust your welder's output amperage to suit the material you are welding and the desired penetration of the

arc.

• If you find the finished weld bead is pitted, with deep cratering at the bead's edges, or the adjacent metal is simply melted or burned away, reduce the amperage incrementally until the condition is corrected. If, on the other hand, you have difficulty striking or maintaining an arc, you may need to increase the amperage.

Steps 17: Clean your finished weld.

• After you have finished welding, you may want to remove the slag and clean up your weld, either to allow paint to bond better, or simply for cosmetic reasons. Chip off the slag and wire brush the weld to remove any foreign material and remaining slag. If the surface needs to be flat to allow fitting the piece you have welded to another piece, use an angle grinder to remove the top, or high portion of the bead. A clean weld, particularly after grinding flat, is easier to examine to see if pitting, puddling, or other defects have occurred while welding.

Steps 18: Paint your weld with a suitable rust-preventative primer to protect it from corrosion.

• Freshly welded metal will corrode rather quickly if exposed to the elements, since the actual base metal is exposed directly to moisture.

Tips…• Some people listen to the sounds produced by the electric arc to judge the quality

of the weld. Popping and snapping sounds may indicate either inconsistent arc gap or improper amperage.

• When joining work-pieces too large to effectively clamp, tack the pieces together with small welds at intervals to prevent the pieces from shifting.

• If you weld in the middle of the day, the pupils of the eyes will be small and less light will enter your eyes. This will reduce the chance of getting severe headaches from retinal damage caused by the light emitted from a the arcs. If you get a severe headache from the arcs, don't worry, stay out of the sun and take aspirin to control the pain and it will heal in 2 to 3 days.

• If you weld out in the sun in the middle of the day, the metal will heat up and it will be easier to start and continue the welds. You can also use a smaller amperage and do a finer job if the metal is warm from the sun.

Warnings…• Inspect cables and connections often to decrease the possibility of accidental electrical shock.

• Arc welding machines utilize a high-amperage electric current which is extremely dangerous, so handle the cables and stinger with care. Never weld in wet conditions or on wet material without proper training.

• Metal remains hot for a long period of time after the weld is complete, so keep pets and children out of the work area until all materials have cooled.

• Protect yourself from flash burns by covering your skin with gloves, a face mask, and sleeves, dependent upon the area being covered. Never ever weld without a protective helmet when Welding.

• See link in citations, below for specific warnings and precautions.

• The bright light from an electric arc can cause burns similar to a sunburn, so wear long sleeved shirts and long pants to reduce exposure.

• Avoid breathing fumes produced from the welding process. This especially applies to galvanized or plated metals, and those metals which have been painted with metal oxide primers. Metal in the lungs can cause cancer.

3.2

MENJELASKAN PROSES KIMPALAN GAS

• Oxy-fuel welding (commonly calledoxyacetylene welding, oxy welding, or gaswelding in the U.S.) and oxy-fuel cuttingare processes that use fuel gases and oxygen toweld and cut metals, respectively. Frenchengineers Edmond Fouché and Charles Picardbecame the first to develop oxygen-acetylene welding in 1903.

• Gas welding is a process of construction that involves the use of gases as well as oxygen to weld metals together. Other names for gas welding are: oxyacetylene welding and oxy welding. Developed in 1903, gas welding is used to weld pipes and tubes together while also being an effective way to repair metals.

Benefits of Gas Welding

• Many professionals use gas welding as the equipment is versatile. Not only can gas welding techniques be used to weld metals together, but the equipment can be used to create metal art projects. Gas welding equipment can be used for welding metals like steel and iron, but metal heating, brazing, and braze welding are also possible.

Gas Welding Equipment• The welding equipment has an oxygen source as well

as a fuel gas source which helps to begin the welding process. With two hoses and two pressure regulators for each source, the welding apparatus works with the torch to weld the materials. If portability is a concern, torches are made with pressurized liquid fuels to lighten the load of the equipment. A regulator is also involved, controlling the pressure from the tanks to the hoses. The user controls the flow of the fuels with the regulator in both the hose and in the cylinder.

Process of Gas Welding

• By using a welding torch, the welder can weld metals together. The metals being welded together are heated to a high enough temperature to melt, but then a filler is added to the melted metal in order to create a strong connection. The oxygen and the fuel is mixed to create a flame which then can be directed along the metal to create the desired effect. The torch is moved by hand to help control the process and final result.

How to Torch WeldTwo Methods: Light the Torch & Use the Torch

• Learning the basics of torch welding is the first step in becoming proficient with many types of welding. However, mastering welding is something that can take time, not necessarily due its difficulty, but because there are many subtleties involved with maneuvering the torch. There are many types of materials that can be welded, and each has its own unique properties. Once you've mastered the oxygen flow and tip size on a torch, you will be ready to practice handling the torch and apply the process to a variety of projects. Use these tips to learn how to torch weld.

Source: https://www.wikihow.com/Torch-Weld

Method 1: Light the Torch

Put on protective

clothing, including

long pants and

shirt, welder's

gloves and eye protection.

Work in an open

space free of any

flammable materials.

Turn on the fuel

adjustment

knob. The knob is

located on the

shorter of the 2

tanks on the torch.

Turn the knob slowly,

about 1/2 inch (1.3

cm), to release the gas.

Light the torch. Tilt

the lighter so that the

fuel is trapped in the

spark cup and slowly light the torch.

Adjust the flame

size. Carefully open

the oxygen valve a

little bit at a time until

you have the size

flame you require. A

steady flame will have

well defined blue edges.

Method 2: Use the Torch

Clean the

material to be

welded. Check the

material you are

welding for rust or

any other debris.

Clean the material

until it is smooth

and free of dirt or debris.

Apply the flame to your weld. Adjust your flame, and begin to carefully move the

torch over the area to be welded. Move at an even pace in order to see your results.

If you hold the flame too closely to the material for too long a period, you will create

holes in the material. Not enough application will result in the piece not melting.Move

your torch in short runs so that you are certain you are getting the result you need.

Pay attention to the angle of the torch and the amount of flame, and adjust

accordingly.

Tips…• When adjusting your flame, pay close attention to the inner blue flame as

that is where the heat will be concentrated. A nice crisp point should be evident without you hearing a loud hissing sound. If the hiss is heard, the torch is turned up too high and may push your weld all over the material.

• If your flame is not getting any blue tint to it, but remains yellow, you don't have enough oxygen open. Adjust the oxygen knob accordingly. Fuel rich flame will be obvious because not only will it be yellow and too cool, It will be very sooty.

• Practice welding on pieces of scrap metal that are close to the same size as the material you will eventually weld. Practice also on different sized pieces in order to get the idea of how to move the torch and at what angles you can hold it.

Warnings…• Only use a spark lighter to light your torch, never

a butane lighter.• In addition to the flame from a torch, sparks will

be thrown throughout the welding process, creating a fire hazard. Work in an open area and keep a fire extinguisher accessible at all times. If you are working outdoors, wet down nearby grass or brush.

How to Set Up an Oxy Acetylene Torch

• An Oxygen Acetylene torch is a tool used to bond two pieces of metal together by means of extreme heat. In addition, Oxygen Acetylene torches can be fitted with a "Cutting Head" and used to cut one solid piece of metal into two or more pieces.

Source:https://www.wikihow.com/Set-Up-an-Oxy-Acetylene-Torch

Clean the nozzle on the

head. This should be

done with a fine, round

metal file. Just make sure

that this nozzle hole is

unobstructed. If holes are

obstructed, a torch tip

bore cleaning tool may be necessary.

Securely fasten the

"head" of the torch

on the end of the

hoses. It should thread

into a socket where

both the Oxygen and

Acetylene hoses come

together. Usually this joint is brass.

Tighten both valves on

the "head" that you just

secured in the

socket. Make sure these

valves are shut

completely; otherwise,

your gas/air mixtures will be off.

Turn on your valves

on the tanks. Acetylene

main valve should only

be opened 1/2 turn, and

the regulator set at 5 to

7 psi (pounds per

square inch). (If

acetylene is turned up

too high, it can become

unstable.) For welding,

the oxygen should be

set between 7 and 10

psi. For cutting, the

oxygen should be set between 15 and 25 PSI.

• Now, this is where a cutting head and a welding head are different. A welding head is simple, and has two valves located near the base of the head. To use this head: Turn on the Acetylene valve until you hear a slight hiss of gas from the nozzle.

• Take your striker/lighter and light the torch.

• This should produce a dark red-orange flame which puts out very putrid black smoke.

• Now, slowly turn on the valve that controls your oxygen, until you see the flame change. Careful: too much oxygen and you can "bleed out" the flame -- which means the flame will go out. In this event, turn the oxygen off and try again.

• The flame should be blue with a white inside tip. The inner, white tip should measure around 3⁄8 inch (1.0 cm) long.

• For cutting, there is a different head. You will notice a trigger, and three tubes going up to the nozzle.First, turn the oxygen that IS released by the trigger, all the way on.

• Turn on the Acetylene valve until you hear a slight hiss of gas from the nozzle.

• Take your striker/lighter and light the torch.

• This should produce a dark red/orange flame, that puts out very putrid black smoke.

• Now, slowly turn on the valve that controls your Oxygen (there are two valves for oxygen on a cutting head, one blocked controlled by the trigger, one unrestricted), until you see the flame change. Careful: too much Oxygen and you can "bleed out" the flame. Meaning the flame will go out. In this event, turn the Oxygen off and try again.

• The flame, when the trigger is NOT compressed, should be a blue flame, measuring about two inches, with about a 1/2" bluish-yellow inner flame.

• When the trigger is compressed, the flame will become much shorter, louder, and faster.

• When cutting, always heat the metal up to a nice cherry red, and then press the trigger for oxygen. Caution: Sparks will be thrown, so be aware and safe

Tips…• Always wear appropriate safety equipment:

– A welding helmet with appropriate UV protection (shade 5 works well)

– Leather welding gloves

– Closed toed Shoes

– Long Pants

– A long, sleeve shirt This is hot work and the clothing makes it hotter, but safety is better than injury.

• Welding and cutting different metals require different temperatures. Adjust your heads, mixtures, and temperatures as required for these metals.– Aluminum and Copper have high thermal conductivity, and may require more heat.

– Cast iron is very brittle, heat it slowly and evenly so it doesn't crack from thermal shock

Warnings…

• Know what acetylene smells like so if it leaks you will know.

• Never, ever weld or cut alone. If there is injury or accident, you need someone around to help or call for help.

3.3

MENJELASKAN PROSES KIMPALAN MIG

• MIG (Metal Inert Gas) Welding or GMAW (Gas Metal Arc Welding):

The concept of combining two pieces of metal together with awire that is connected to an electrode current, is referred toas Metal Inert Gas (MIG) welding. In this type of weldingprocess, a shielded gas is used along the wire electrode, whichheats up the two metals to be joined. A constant voltage anddirect current power source is required for this method, andthis is the most common industrial welding process. The MIGor GMAW process is suitable for fusing mild steel, stainless-steel as well as aluminium.

Basic MIG welding techniques

• This is a basic guide on how to weld using a metal inert gas (MIG) welder. MIG welding is the awesome process of using electricity to melt and join pieces of metal together. MIG welding is sometimes referred to as the "hot glue gun" of the welding world and is generally regarded as one of the easiest type of welding to learn.

**This Instructable is not intended to be THE definitive guide on MIG welding, for that you might want to seek out a a more comprehensive guide from a professional. Think of this Instructable as a guide to get you started MIG welding. Welding is a skill that needs to be developed over time, with a piece of metal in front of you and with a welding gun/torch in your hands.**

Step 1: Background

• MIG welding was developed in the 1940's and 60 years later the general principle is still very much the same. MIG welding uses an arc of electricity to create a short circuit between a continuously fed anode (+ the wire-fed welding gun) and a cathode ( - the metal being welded).

• The heat produced by the short circuit, along with a non-reactive (hence inert) gas locally melts the metal and allows them to mix together. Once the heat is removed, the metal begins to cool and solidify, and forms a new piece of fused metal.

• A few years ago the full name - Metal Inert Gas (MIG) welding was changed to Gas Metal Arc Welding (GMAW) but if you call it that most people won't know what the heck your talking about - the name MIG welding has certainly stuck.

• MIG welding is useful because you can use it to weld many different types of metals: carbon steel, stainless steel, aluminum, magnesium, copper, nickel, silicon bronze and other alloys.

Here are some advantages to MIG welding:

• The ability to join a wide range of metals and thicknesses

• All-position welding capability• A good weld bead• A minimum of weld splatter• Easy to learn

Here are some disadvantages of MIG welding:

• MIG welding can only be used on thin to medium thick metals

• The use of an inert gas makes this type of welding less portable than arc welding which requires no external source of shielding gas

• Produces a somewhat sloppier and less controlled weld as compared to TIG (Tungsten Inert Gas Welding)

Step 2: How the Machine Works

The Welder

• Inside the welder you will find a spool of wire and a series of rollers that pushes the wire out to the welding gun. There isn't much going on inside this part of the welder, so it's worth it to take just a minute and familiarize yourself with the different parts. If the wire feed jams up for any reason (this does happen from time to time) you will want to check this part of the machine out.

• The large spool of wire should be held on with a tension nut. The nut should be tight enough to keep the spool from unraveling, but not so tight that the rollers can't pull the wire from the spool.

• If you follow the wire from the spool you can see that it goes into a set of rollers that pull the wire off of the big roll. This welder is set up to weld aluminum, so it has aluminum wire loaded into it. The MIG welding I am going to describe in this instructable is for steel which uses a copper colored wire.

The Gas Tank

• Assuming you are using a shielding gas with your MIG welder there will be a tank of gas behind the MIG. The tank is either 100% Argon or a mixture of CO2 and Argon. This gas shields the weld as it forms. Without the gas your welds will look brown, splattered and just generally not very nice. Open the main valve of the tank and make sure that there is some gas in the tank. Your gauges should be reading between 0 and 2500 PSI in the tank and the regulator should be set between 15 and 25 PSI depending on how you like to set things up and the type of welding gun you are using.

**It's a good rule of thumb to open all valves to all gas tanks in a shop only a half turn or so. Opening the valve all the way doesn't improve your flow any more than just cracking the valve open since the tank is under so much pressure. The logic behind this is so that if someone needs to quickly shut off gas in an emergency they don't have to spend time cranking down a fully open valve. This might not seem like such a big deal with Argon or CO2, but when your working with flammable gases like oxygen or acetylene you can see why it might come in handy in the event of an emergency.**

• Once the wire passes through the rollers it is sent down a set of hoses which lead to the welding gun. The hoses carry the charged electrode and the argon gas.

The Welding Gun• The welding gun is the business end of things. It's where most of

your attention will be directed during the welding process. The gun consists of a trigger that controls the wire feed and the flow of electricity. The wire is guided by a replaceable copper tip that is made for each specific welder. Tips vary in size to fit whatever diameter wire you happen to be welding with. Most likely this part of the welder will already be set up for you. The outside of the tip of gun is covered by a ceramic or metal cup which protects the electrode and directs the flow of gas out the tip of the gun. You can see the small piece of wire sticking out of the tip of the welding gun in the pictures below.

The Ground Clamp

• The ground clamp is the cathode (-) in the circuit and completes the circuit between the welder, the welding gun and the project. It should either be clipped directly to the piece of metal being welding or onto a metal welding table like the one pictured below (we have two welders hence two clamps, you only need one clamp from the welder attached to your piece to weld).

• The clip must be making good contact with the piece being welded for it to work so be sure to grind off any rust or paint that may be preventing it from making a connection with your work.

Step 3: Safety Gear

• MIG welding can be a pretty safe thing to do so long as you follow a few important safety precautions. Because of MIG welding produces lots of heat and lots of harmful light, you need to take a few steps to protect yourself.

Safety Steps:• The light that is generated by any form of arc welding is extremely bright.

It will burn your eyes and your skin just like the sun will if you don't protect yourself. The first thing you will need to weld is a welding mask. I am wearing an auto-darkening welding mask below. They are really helpful if you are going to do a bunch of welding and make a great investment if you think you will be working with metal often. Manual masks require you to jerk your head dropping the mask into position or require to use a free hand to pull the mask down. This allows you to use both your hands to weld, and not worry about the mask. Think of protecting others from the light as well and use a welding screen if it's available to make a border around yourself. The light has a tendency to draw on lookers who might need to shielded from being burned too.

• Wear gloves and leathers to protect yourself from molten metal splattering off of your work piece. Some people like thin gloves for welding so you can have a lot of control. In TIG welding this is especially true, however for MIG welding you can wear whatever gloves you feel comfortable with. The leathers will not only protect your skin from the heat produced by welding but they will also protect your skin from the UV light produced by welding. If you are going to be doing any amount of welding more than just a minute or two you will want to cover up because UV burns happen fast!

• If you are not going to wear leathers at least make sure that you are wearing clothing made from cotton. Plastic fibers like polyester and rayon will melt when they come into contact with molten metal and will burn you. Cotton will get a hole in it, but at least it won't burn and make hot metal goop.

• Do not wear open toed shoes or synthetic shoes that have mesh over the top of your toes. Hot metal often falls straight down and I have burned many holes through the tops of my shoes. Molten metal + hot plastic goo from shoes = no fun. Wear leather shoes or boots if you have them or cover your shoes in something non-flammable to stop this.

• Weld in a well ventilated area. Welding produces hazardous fumes which you shouldn't breathe in if you can avoid it. Wear either a mask, or a respirator if you are going to be welding for a prolonged amount of time.

Important Safety Warning

• DO NOT WELD GALVANIZED STEEL. Galvanized steel contains a zinc coating that produces carcinogenic and poisonous gas when it is burned. Exposure to the stuff can result in heavy metal poisoning (welding shivers) -flu like symptoms that can persist for a few days, but that can also cause permanent damage. This is not a joke. I have welded galvanized steel out of ignorance and immediately felt it's effects, so don't do it!

Fire Fire Fire• Molten metal can spit several feet from a weld.

Grinding sparks are even worse. Any sawdust, paper or plastic bags in the area can smolder and catch fire, so keep a tidy area for welding. Your attention will be focused on welding and it can be hard to see what's going on around you if something catches fire. Reduce the chance of that happening by clearing away all flammable objects from your weld area.

• Keep a fire extinguisher beside the exit door from your workshop. CO2 is the best type for welding. Water extinguishers are not a good idea in a welding shop since you are standing next to a whole lot of electricity.

Step 4: Prep for Your Weld

Before you start welding make sure

things are properly setup at both

the welder and on the piece you are about to weld.

The Welder

• Check to make sure that the valve to the shielding gas is open and that you have around 20ft3/hr flowing through the regulator. The welder

needs to be on, the grounding clamp attached to your welding table or to the piece of metal directly and you need to have proper wire

speed and power setting dialed in (more on that later).

The Metal

• While you can pretty much just take a MIG welder, squeeze the trigger and and touch it to your work piece to weld you won't get a great result. If you want the weld to be strong and clean, taking 5 minutes to clean your metal and grind down any edges that are being joined will really help your weld.

• While you can pretty much just take a MIG welder, squeeze the trigger and and touch it to your work piece to weld you won't get a great result. If you want the weld to be strong and clean, taking 5 minutes to clean your metal and grind down any edges that are being joined will really help your weld.

• Using an angle grinder to bevel the edges of some square tube before it gets welded onto another piece of square tubing. By creating two bevels on the joining edges it makes a little valley for the weld pool to form in. Doing this for butt welds (when two things are pushed together and joined) is a good idea.

Step 5: Laying a Bead

1 - These settings are pretty good.

2 - Not enough power, not enough wire feed.

3 - Good wire feed, not enough power.

4 - Good wire feed, not enough power.

5 - It takes a little while to get comfortable, don't be afraid to make some test welds to get a feel for it.

• Once your welder is set up and you have prepped your piece of metal it's time to start focusing on the actual welding.

If it's your first time welding you might want to practice just running a bead before actually welding two pieces of metal together. You can do this by taking a piece of scrap metal and making a weld in a straight line on its surface.

• Do this a couple of times before you start actually welding so that you can get a feel for the process and figure out what wire speed and power settings you will want to use.

Every welder is different so you will have to figure these settings out yourself. Too little power and you will have a splattered weld that won't penetrate through your work piece. Too much power and you might melt right through the metal entirely.

• The pictures below show a few different beads being laid down on some 1/4" plate. Some have too much power and some could use a little more. Check out the image notes for the details.

The basic process of laying a bead is not too difficult. You are trying to make a small zig zag with the tip of the welder, or little concentric circles moving your way from the top of the weld downward. I like to think of it as "sewing" motion where I use the tip of the welding gun to weave the two pieces of metal together.

• First start laying beads about an inch or two long. If you make any one weld too long your work piece will heat up in that area and could become warped or compromised, so it's best to do a little welding in one spot, move to another, and then come back to finish up what's left in between.

What are the right settings?• If you are experiencing holes in your workpiece than your power is

turned up too high and you are melting through your welds.• If your welds are forming in spurts your wire speed or power

settings are too low. The gun is feeding a bunch of wire out of the tip, it's then making contact, and then melting and splattering without forming a proper weld.

• You'll know when you have settings right because your welds will start looking nice and smooth. You can also tell a fair amount about the quality of the weld by the way it sounds. You want to hear continuous sparking, almost like a bumble bee on steroids.

Step 6: Welding Metal Together

• Once you've got your method tested out a bit on some scrap, it's time to do the actual weld. In this photo I am doing just a simple butt weld on some square stock. We've already ground down the edges of the surfaces that are going to be welded so that the seem where they meet makes a small "v".

• We are basically just taking the welder and making our sewing motion across the top of the seem. It's ideal to weld from the bottom of the stock up to the top, pushing the weld forward with the tip of the gun, however that isn't always comfortable or a good way to start learning. In the beginning it's perfectly fine to weld in whatever direction/position that is comfortable and that works for you.

• Once we finished welding the pipe we were left with a big bump where the filler came in. You can leave that if you like, or you can grind it flat depending on what you are using the metal for. Once we ground it down we found once side where the weld didn't penetrate properly. (See photo 3.) That means that we need to have more power and more wire to fill in the weld. We went back and redid the weld so that it was properly joined.

Step 7: Grind Down the Weld

• If your weld isn't on a piece of metal that will show, or if you don't care about how the weld looks, then you are done with your weld. However, if the weld is showing or you are welding something that you want to look nice then you will most likely want to grind down your weld and smooth it out.

• Slap a grinding wheel onto an angle grinder and get started grinding on the weld. The neater your weld was the less grinding you will have to do, and after you have spent a whole day grinding, you will see why it's worth it to keep your welds neat in the first place. If you use a ton of wire and made a mess of things it's ok, it just means that you might be grinding for a while. If you had a neat simple weld though, then it shouldn't take too long to clean things up.

• Be careful as you approach the surface of the original stock. You don't want to grind through your nice new weld or gouge out a piece of the metal. Move the angle grinder around like you would a sander so as not to heat up, or grind away any one spot of the metal too much. If you see the metal get a blue tinge to it you are either pushing too hard with the grinder or not moving the grinding wheel around enough. This is can happen especially easily while grinding thing sheets of metal.

• Grinding welds can take a while to do depending on how much you have welded and can be a tedious process - take breaks while grinding and stay hydrated. (Grinding rooms in shops or studios tend to heat up, especially if you are wearing leathers). Wear a full face mask when grinding, a mask or respirator, and ear protection. Make sure that all your clothing is neatly tucked in and that you don't have anything hanging down from your body that could get caught in the grinder - it spins fast

• When you are done your piece of metal might look something like the one in the second photo pictured below. (Or maybe better as this was done by a few Instructables Interns at the beginning of the summer during their first welding experience.)

Step 8: Common Problems

Lots of weld splatter here. Possibly caused

by incorrect wire feed speed.

It can take a good amount of practice to start welding reliably every time, so don't worry if you have some problems when you first stop. Some common problems are:

• No or not enough shielding gas from the gun is surrounding the weld. You can tell when this happens because the weld will start splattering little balls of metal, and will turn nasty colors of brown and green. Turn up the pressure on the gas and see if that helps.

• Weld is not penetrating. This is easy to tell as your weld will be weak and won't be fully joining your two piece of metal.

• Weld burns a while right through your material. This is caused by welding with too much power. Simply turn down your voltage and it should go away.

• Too much metal in your weld pool or the weld is globy like oatmeal. This is caused by too much wire coming out of the gun and can be fixed by slowing down your wire speed.

• Welding gun spits and does not maintain a constant weld. This could be caused because the gun is too far from the weld. You want to hold the tip of the gun about 1/4" to 1/2" away from the weld.

Step 9: Wire Fuses to Tip/Change the Tip

• Sometimes if you are welding too close to your material or you are building up too much heat the tip of the wire can actually weld itself onto the tip of your welding gun. This looks like a little blob of metal at the tip of your gun and you'll know when you have this problem because the wire won't come out of the gun anymore. Fixing this is pretty simple if you just pull on the blob with a set of pliers. See photos 1 and 2 for visuals.

• If you really scorch the tip of your gun and fuse the hole closed with metal then you need to turn the welder off and replace the tip. Follow the steps and the overly detailed photo series below to see how it's done. (It's digital so I tend to take too many pictures).

Photo 4Photo 3

Photo 5 Photo 6

Photo 8Photo 7

Photo 9

1. (Photo 3) - The tip is fused closed.

2. (Photo 4) - Unscrew the welding shield cup.

3. (Photo 5) - Unscrew the bad welding tip.

4. (Photo 6) - Slide a new tip into place.

5. (Photo 7) - Screw the new tip on.

6. (Photo 8) - Replace the welding cup.

7. (Photo 9) - It's now good as new.

Step 10: Replace Wire Feed to Gun

• Sometimes the wire gets kinked and won't advance through the hose or the gun even when the tip is clear and open. Take a look inside of your welder. Check out the spool and the rollers as sometimes the wire can become kinked in there and need to be re-fed through the hose and the gun before it will work again. If this is the case, follow these steps:

Unplug the unit.

Find the kink or jam in the spool.

Cut the wire with a set of pliers or wire cutters.

Take the pliers and pull out all of the wire from the hose through the tip of the gun.

Keep pulling, it's long.

• Unkink the wire and feed it back into the rollers. To do this on some machines you have to release the tension spring holding the rollers down tight on the wires. The tension bolt is pictured below. It's the spring with the wing nut on it in it's horizontal position (disengaged).

Check to make sure the wire is properly seated between the rollers.

Re-seat the tension bolt.

• Turn on the machine and depress the trigger. Hold it down for a while until the wire comes out of the tip of the gun. This can take 30 seconds or so if your hoses are long.

PENTAKSIRAN:

KUIZ

UJIAN

AMALI

ALHAMDULILLAH