1、WeldingBasics1 http:/www.WelderWPage2 Table Of Contents What is Welding? . 3 The History of Welding . 6 Welding Terminology/Welding Glossary of Terms . 9 Types of Welding . 12 TIG(GTAW) Welding Process Overview . 15 TIG(GTAW) Welding Tips and Basics . 18 MIG(GMAW) or Wire Feed Welding Process Overvi
2、ew . 20 MIG (GMAW) or Wire Feed Welding Process Tips and Basics . 22 Stick Welding Process Overview . 25 Stick Welding Tips and Basics . 28 Flux Core Welding Overview . 30 Submerged Arc Welding (SAW) Overview . 33 Brazing Overview . 36 Robotic Welding Overview . 38 Laser Welding Overview . 41 Ultras
3、onic Welding Overview . 45 Stud Welding Overview . 48 Underwater Welding Overview. 50 Plastic Welding . 52 Thermite Welding . 55 Finding a Good Welding School to Learn Welding . 57 Weld Symbols . 60 Welding Job Types . 62 WeldingBasics1 http:/www.WelderWPage3 What is Welding? Wikipedia defines weldi
4、ng as “a fabrication process that joins materials, usually metals.” This is done by melting the part of the materials to be joined and adding some additional molten joining material. When the molten material cools, it forms a strong bond or joint. Welding is the most widely practiced way of joining
5、metals together due to the efficiency and economy of the process. It has been estimated that approximately 50% of the Gross National Product of the USA arises from activities that are in some for or another related, perhaps remotely, to welding. As an example, farming may appear to have nothing to d
6、o with welding, but the equipment the framer uses to grow and harvest his crops will have used welding in their manufacturing process. Until the advent of the 20th century, welding was confined to blacksmith shops where two pieces of metal were heated to very high temperatures in a forge and then ha
7、mmered together until the joining occurred. This is what is called forge welding. With the introduction of electricity into industrial processes, welding became both quicker and easy, and also more economical. Today there are 4 types of welding techniques that are commonly used. The most basic for i
8、s Arc Welding where the parts to be joined together are brought into contact with strong electrical current and heated. The molten parts are then joined together to form a WeldingBasics1 http:/www.WelderWPage4 weld. This is the low technology end of welding in its cheapest and least sophisticated fo
9、rm. Gas Welding is generally used for repair work especially in the case hollow items like tubes and pipes. Hot gas is forced onto the surfaces to be welded. This procedure requires the parts to be subjected to less heat and is suitable for material that may be damaged by exposure to high temperatur
10、e. For this reason it is used in the jewellery industry which has to work with soft metal with low melting points. Resistance Welding requires that an additional sheet of material is used to cover the pieces that are to be welded together. This provides great strength to a weld, but the process requ
11、ires expensive equipment and also the use of additional material to encase the weld which makes it expensive and not suitable for all applications. Laser Welding is the most modern technology available. High intensity lasers can be tightly focused and produce controllable heat on the surfaces to be
12、welded very quickly. This is perfect for material which can be damaged by prolonged exposure to extreme heat. Laser welding is very accurate and can be used to produce even the smallest of welds. However, because of the high capital cost involved in purchasing this equipment, the cost of welding is
13、also high. Although the perception of welding is that of a simple process of heating and joining, it is a high technology industry with huge amounts being spent of research and development to find stronger, more accurate and cheaper methods. The welding process plays a big role in WeldingBasics1 htt
14、p:/www.WelderWPage5 metallurgy with a constant effort underway to find newer and more weld friendly alloys. WeldingBasics1 http:/www.WelderWPage6 The History of Welding When you drive your car or look at a light fixture in the street or open your microwave, chances are that there is something in any
15、 of those items that has been welded. These products and others have been a part of the process of welding for more years than you might imagine. Welding actually started a very long time ago during the Middle Ages. Many artifacts have been found that date back to the Bronze Age. These have been sma
16、ll boxes that were welded together with what is called lap joints; no one is exactly sure what these were used for, but this was important to that time. The Egyptians also made a variety of tools by welding pieces of iron together. Perhaps this is where Maxwells Hammer comes later? Who can say! Then
17、 came the rise of the Middle Ages and many people there were able to use blacksmithing for iron. Different modifications were made along the way until the welding that is used to day was developed. There were several significant inventions in the 1800s that influenced welding included here: ? The in
18、vention of acetylene by an Englishman named Edmund Davy. ? Gas welding and cutting became known and a way to cement pieces of iron together. ? Arc lighting was a very popular part of welding after the electric WeldingBasics1 http:/www.WelderWPage7 generator became known. ? Arc and resistance welding
19、 become another popular aspect of welding. ? Nikolai N. Benardos receives a patent for welding in 1885 and 1887 from America and Britain. ? C.L. Coffin receives an American patent for a arc welding process. After the 1800s many more patents and inventions were made in order to create more ways of do
20、ing welding but one of the greatest needs would come much later during World War I because this process was needed to create arms. Because of the demand welding firms became a staple of America and Europe because the war needed welding machines and electrodes to go with them. During the war people r
21、eally got a chance to look at how welding worked and it became a very popular way of work. So much so that in 1919 the first American Welding Society was begun. This nonprofit organization came directly out of through a group of men who called themselves the Wartime Welding Committee of the Emergenc
22、y Fleet Corporation (Source: Miller Welds). The 1950s and 1960s were also a significant time for welding because a welding process using CO2 was discovered and a variation of this form of welding that used inert gas became very popular in the 1960s because it produced a different type of arc. There
23、have been a number of improvements in the welding trade over these years and today the process has added two areas, friction and WeldingBasics1 http:/www.WelderWPage8 laser welding. These two have created a more specialized field and therefore more opportunities for learning. One interesting point a
24、bout laser welding is that those people who use it have found that is a tremendous heat source so it can actually weld both metal and non-metal objects. WeldingBasics1 http:/www.WelderWPage9 Welding Terminology/Welding Glossary of Terms If you are interesting in welding there are many different term
25、s that you will want to familiarize yourself with in order to read magazines or books on the topic. Here is a list of common terms that are important to know: ACETYLENE - this is a gas that you will be working with to do welding. It is a very flammable gas so you have to be careful with it. This gas
26、 is made up of carbon and hydrogen and it is used in the oxyacetylene type of welding process. AIR-ACETYLENE - this is a flare that you can produce using low temperature. It is created when you burn acetylene with air and not oxygen. AIR-CARBON ARC CUTTING (CAC-A) - this is a way of arc cutting wher
27、e you melt metals through the heat of a carbon arc. ALLOY - this is a mix that has metallic properties because it has at least one element that is metal, but it can have several other things in the mix as long as one is metal. ALTERNATING CURRENT - a current that goes backward and forward at regular
28、 intervals (see DC Current). WeldingBasics1 http:/www.WelderWPage10 BACK FIRE - this is the popping sound that you hear when you turn on the acetylene torch when you connect it with fire. It is created because the flame turns back into the tip for a moment and then comes back out of the torch as a f
29、lame. BACKHAND WELDING - this is a special welding technique where you point the flame at the weld that is already completed. BACKING STRIP - this is a strip of material that you will use when you need to keep metal that is melted at the bottom of the weld. You may also use this strip to add strengt
30、h to the thermal load of a joint so you can stop the base of the metal from warping too much. BASE METAL - this is what you call the metal that you are going to weld or that you are going to cut. If this is an alloy, it will be the metal that you have in the highest amount. BRAZING - this is actuall
31、y several welding processes. You will use this when you have a groove, fillet, lap or flange joint that you need to bond. This will require a nonferrous filler metal that has a melting point higher than 800 degrees F (427 degrees C) but less then your base metals. Then, the filler metal will be dist
32、ributed throughout the joint using capillary attraction. DIRECT CURRENT (DC) - a current that only flows in one direction - forward. - Flows in one direction and does not reverse its direction of flow. WeldingBasics1 http:/www.WelderWPage11 DEFECT - there can be defects in your weld after you create
33、 it. The main defects you can find are things like cracks, porosity, places where the metal has been undercut, or where you have a slag inclusion. EDGE JOINT - this is where you set two plates and put them together at a 90 degree angle with their outer edges. WeldingBasics1 http:/www.WelderWPage12 T
34、ypes of Welding When you think about welding you might think that there is only one type of welding. This is a common idea because most people only see the finished product. However, there are many different types of welding that you might find interesting. Welding is a way of joining metals to each
35、 other to make them firm and the metal forms a bond that is tight. There are a variety of bonds that are done depending on the types of welding you use. Types of welding fit under categories as listed here: Gas welding This type of welding creates a flame from a burning gas and this creates the weld
36、ing heat that is needed. You will see this in the following types of welding: Propane torches - people use this when they want to sweat a joint or when they want to solder two pieces of metal together. This is one of the lowest heats and can be used for small things. Oxyacetylene torch- this heat ge
37、ts a bit hotter and many people say this is the most universal type of welding tool you can find. This is used when you need a very hot flame. This type of torch will weld a variety of things as long as you have the right metals and tools for it. It is generally used when you want to cut, braze, wel
38、d or solder something that requires a higher heat. You have to be careful though WeldingBasics1 http:/www.WelderWPage13 because it is a type of heat that can be difficult to control and it can sometimes overheat the area. Oxy-propane - this type of welding is used when you want to solder, braze or h
39、eat something. This is a cheaper form of both of the types of welding that was first listed. Arc welding This type of welding creates the heat through the use of an electric arc. The types of welding that are done through this type of welding include: Basic AC & DC arc welders - when you are looking
40、 for a way to weld either heavy gauge steel or cast iron this is the type of welding to use. It uses rods that you guide along the place to be weld and these are made of flux coated steel or other materials. MIG (Metal Inert Gas) - this is a very quick way of welding and some say it is easier to do
41、than regular arch welding. It is done through the use of a DC arc and it uses filler metal that is used with a spool of thin wire. You use inert gas instead of flux. This is usually used with steal bodywork and is a good choice when you need to weld sheet metal. TIG (Tungsten Inert Gas) - this type
42、of welding uses an AC arc that is of high frequency and it is combined with a tungsten electrode that is shielded by inert gas. This comes together to create a torch that is controllable. This is a good choice to weld very thin metals WeldingBasics1 http:/www.WelderWPage14 together. If you are worki
43、ng with aluminum or stainless steel this is a good choice. WeldingBasics1 http:/www.WelderWPage15 TIG(GTAW) Welding Process Overview The acronym TIG stands for Tungsten Inert Gas Arc Welding and the acronym GTAW stands for Gas Tungsten Arc Welding this is the same process but it is referred to by th
44、ese two different names. In the situation you will be welding using an electric arc that generates the heat. You then have a tungsten non-consumable electrode that then produces the weld you are attempting to make. One of the things that have to happen in this type of welding is that the particular
45、metal that you are welding has to be shielded from contamination in the atmosphere or you will get a poor weld. Because of this, the area is shielded using an inert gas like argon; this is used with a filler metal where necessary. This type of welding needs constant current to flow across the arc us
46、ing an ionized gas called plasma. Plasma also has metal vapours within it. You will usually use GTAW if you have to weld thin metals like stainless steel, aluminium, magnesium or copper allows. GTAW also gives the person who is operating the welding process more control of the weld. What this means
47、to the weld is that it is a stronger weld and has a higher quality than many other types of welding. Many experts say WeldingBasics1 http:/www.WelderWPage16 that it is harder to learn, is complex and can be slower than other welding techniques. Some welders like using a different kind of torch to pr
48、oduce plasma arc welding which is very much like this one but a little different. This type of welding will give a more focused welding arc, but usually this is done through automation. How It Operates The reason this welding process is the most complicated or difficult to master is because the weld
49、er has to use a smaller arc length; they have to be able to have a very steady hand. If they arent able to keep a distance between the electrode and the piece they are working on, the piece can become contaminated and there can be problems with the weld. This is also a two handed process because you
50、 have to be able to hold the torch in one hand and feed a filler metal into the space that you are welding. You can see that this is a very intricate process and one that requires high skill. There are a few types of welding that will not require this type of weld and the individual will not have to
