Introduction to Manufacturing System 101

Group Project (Welding)

Mytham Alasker 201701719

Ahmed Alabbas 201601497

Danyal Alawami 201700096

Spring 2020

I. IntroductionA. DefinitionB. The importance of weldingC. Types of welding processes

II. Oxyfuel Gas Welding (OFW)A. DefinitionB. DetailsC. What is it used for?

III. Arc Welding (W)A. DefinitionB. DetailsC. What is it used for?

IV. Resistance Welding (RW)A. DefinitionB. DetailsC. What is it used for?

V. Solid State Welding (SSW)A. DefinitionB. DetailsC. What is it used for?

VI. Unique ProcessesA. DefinitionB. DetailsC. What is it used for? For each process

VII. ConclusionA. Advantages and disadvantages in welding mainlyB. What are some of the most common welding processes and why?C. What is the strongest type of weld?D. What is the best welder for a beginner?

Welding

Welding is the joining of metals. What welding does is join metals or other materials at

their molecular level with the technology we have at the moment. I say “at the moment" because

welding technology is always changing, and with so many military forces relying on it to make

their defense products, there are welding processes we are yet to hear about. What we do know

about modern welding is that a weld has four components. The four components are the metals

themselves, a source of heat, filler material, and some form of air-shield. That is how the welding

process works. The metal gets heated to its melting point, at the same time there is some sort of

shielding from the air to protecting it, and then a filler metal is added to the area that needs to be

joined ultimately producing a single piece of metal. They will be using a direct casting method

back in the day when the bronze and iron ages began using metals more productively. The

casting process will be accomplished by making the piece to be inserted using a sand mold. Just

place it on top of the metal frame you decided to add a frame to it until the mold was made and

fill it with hot molten metal, after which you are waiting for it to cool down. Another way metal

was joined was by putting two pieces of metal together and damming any open sides. Once the

area was leak free you simply poured molten metal to fill the joint.

The importance of welding

1. It is a permanent joint that provided adequate strength as per the requirement.

2. Welding done in an organized way will provide leak-proof joint.

3. Suppose the purpose is to join to plates in butt joint configuration, at this point riveted

joint, bolted joint are of no use, even if you joined them backing strap is required and still

required strength will not be there, at this stage welding is optimal way for joining.

4. Proper welding joint provides strength more than the base material as in case of

submerged arc welding (SAW) and in other processes too.

5. Nowadays in major of application, you will find the use of welding.

6. Components of thicker dimensions can be joined through welding in a convenient way.

Types of welding processes

1. Oxyfuel Gas Welding (OFW)

2. Arc Welding (W)

3. Resistance Welding (RW)

4. Solid State Welding (SSW)

5. Unique Processes

Oxyfuel Gas Welding (OFW)

Welding of oxyacetylene, also known as Oxy-fuel Welding (OFW), it involves any

welding process using oxygen combustion as the heating medium. The base metal and a filler rod

are melted with this family of processes using a flame created at the tip of a welding torch. Inside

a mixing chamber in the torch, fuel gas and oxygen are mixed in the proper proportions. Molten

metal from the plate edges and filler metal, if used, intermix in a common molten pool and join

when cooling. Commonly-used fuel gases include acetylene, propylene, propane and natural gas.

The equipment used in oxyacetylene welding is small in cost, typically compact, and flexible

enough to be used for a variety of similar operations such as bending and straightening,

preheating, post-heating, surfacing, brazing and brace welding. Acetylene meets the criteria for

both of these applications the most closely among commercially available fuel gasses. The

overall flexibility of simple oxyacetylene welding equipment is greatly improved by cutting

wires, multi-flame heating nozzles and a range of special application accessories. The manual

and mechanized oxygen cutting operations can be conducted with fairly simple adjustments in

the equipment. Usually welded metals include carbon steels and low alloy steels, and most

nonferrous metals.

Why use OFW?

Oxyacetylene welding is ideally suited for repair welding and for welding thin sheets,

tubes and small diameter pipes

Welder can exercise precise control over heat input and temperature, independent of the

addition of filler metal

Minimal dilution with the base material makes OFW suitable for surfacing applications

Use of a reducing flame can assist in carburization of the surface to be welded

Advantages of OFW

Simple and straightforward operation.

3 distinct flame settings are possible: neutral, oxidizing and carburizing.

Produces enough heat to weld steel.

Portable, easy to operate equipment.

Produces less intense flames and UV rays than other methods.

High degree of operator control over heat input, weld zone temperature, and weld bead

size and shape.

Excellent for repair welds, thin sheets, tubes, and small pipe diameters.

Limitations of OFW

Quality is dependent on operator skill, equipment, and plate conditions.

Not ideal for stainless steels or aluminum. Better suited for alloys and mild steels.

May require more finishing, depending on operator skill and intended use of finished

piece.

Large heat affected zones (HAZ).

Arc Welding (W)

Arc welding is a type of welding process using an electric arc to create heat to melt and

join metals. A power supply creates an electric arc between a consumable or non-consumable

electrode and the base material using either direct (DC) or alternating (AC) currents. Arc

welding is a fusion welding process used to join metals. An electric arc from an AC or DC power

supply creates an intense heat of around 6500°F which melts the metal at the join between two

work pieces.

The arc can be directed either manually or mechanically along the join axis, while the electrode

either simply carries the current, or conducts the current and simultaneously melts into the weld

pool to supply the join with filler metal. Since the metals chemically react to oxygen and

nitrogen in the air when heated by the arc to high temperatures, a protective shielding gas or slag

is used to reduce the molten metal's interaction with the air. The molten metals, once cooled,

solidify to form a metallurgic bond.

Advantages of arc welding

Cost – equipment for arc welding is well-priced and affordable, and the process often

requires less equipment in the first place because of the lack of gas.

Portability – these materials are very easy to transport.

Works on dirty metal.

Shielding gas isn’t necessary – processes can be completed during wind or rain, and

spatter isn’t a major concern.

Disadvantages of arc welding

Lower efficiency – more waste is generally produced during arc welding than many other

types, which can increase project costs in some cases

High skill level – operators of arc welding projects need a high level of skill and training,

and not all professionals have this

Thin materials – it can be tough to use arc welding on certain thin metals

Resistance Welding (RW)

Resistance welding is the joining of metals by applying pressure and transmitting current

through the metal region to be joining for a long period time. The main benefit of resistance

welding is that there is no need for any other materials to build the bond, making this method

extremely cost efficient. There are various methods of resistance welding (e.g. spot and seam,

projection, and flame) which vary mainly in the styles and shapes of welded electrodes used to

apply the pressure and perform the current. The electrodes, usually made from copper-based

alloys due to superior conductive properties, are cooled by water flowing into cavities between

the electrode and the resistance welding machine’s other conductive tooling device. Resistance

welding machines are designed and developed for a wide range of applications in the

automotive, aerospace and industrial sectors. The operation of these devices is highly regulated

and repeatable by automation, enabling factories to produce workers readily.

Resistance welding processes

Based on the shape of the workpieces and the position of the electrodes, resistance

welding methods can be divided into many types, with spot welding, projection welding seam

welding and butt welding, being the most widely used.

Spot welding

Spot welding is a resistance welding method for connecting sheets of metal by applying

opposing forces directly to electrodes with pointing tips. The current and the production of heat

are located by electrodes in shape. The size of the weld nugget is typically determined by the

contact area of the electrode tip. Spot welding is the prevalent joining method for connecting

vehicle bodies and large parts in the car industry. This is also commonly used for the

manufacture of furniture and household appliances.

Seam welding

Seam welding is a resistance welding process for joining metal sheets in continuous,

often leak-tight seam joints by applying directly opposing forces with rotary wheel electrodes.

The peripheral shapes of the electrode wheels locate the current and heat generation.

Application of resistance welding

Resistance welding is being used where it can sustain long production tomes and stable

conditions.

Welding happens with operating who usually load and unload the welding machine and

use the switch to start the welding process.

The automobile industry, preceded by the appliance industry, is the main user of the

resistance welding processes. Most companies producing a range of items made of

thinner gauge metals use resistance welding.

This method of welding is often used for production of pipe, and smaller structural part in

the steel in the steel industry.

This has the advantage of delivering a high-speed work and needs no filler materials.

Welds are reproducible and natural welds of good quality.

Solid State Welding (SSW)

In any of those welding processes in which the melting of faying parent material surfaces

does not occur is caller solid-state welding. Unlike fusion welding, it is not appropriate to add

heat here. To obtain a sound joint, however, the application of pressure is needed and is therefore

also called pressure welding. It is meaningless that often base materials are heated to a high

temperature while being joined by solid-state welding process; however, temperature remains

always below melting point.

Advantages and disadvantages of SSW

Advantages Disadvantages

- These processes have a comparatively lower distortion lever and the generation of residual stress due to no melting and solidification.

- Special form of joint design, edge preparation and/or surface finish is required.

- There is also smaller heat affected region (HAZ).

- The primary shape of the component is crucial because it allows pressure to be applied (a suitable shape is needed to apply pressure evenly).

- It gives the sumptuous appearance of a weld

- It is difficult to combine more than two components at a time; in some situations, this is impossible.

- As no fusion occurs, the mechanical properties of parent materials remain intact.

- Filler material can not be added, and it is impossible to fill the larger root void.

Examples of SSW

Any welding process when no melting occurs falls under this category. While there are

many processes of fusion welding, quite few processes of solid-state welding still exist. Note that

several people find resistance welding category as solid-state welding; here, the same retained

under fusion welding as nugget is created by resistance heating due to melting of faying surfaces.

Here are some examples:

Cold Welding (CW)

Diffusion Welding (DFW)

Cold Welding

Cold welding (aka contact welding) is a bonding process at the point where the two

metals are joined, and does not require heat or fusion. Such two processes are without a molten /

liquid stage. Cold welding was discovered in the 1940s and it was found that if brought into

contact in a vacuum two identical, clean metals would bond. Among a few reasons, obtaining a

perfect cold weld can be a challenge because of the oxide layers that form in most environments

on the top of the metals, defects, surface contamination, etc.

Cold welding is considered the best welding method for joining metals and forming a

bond-like parent metal. It is perfect to combine the metals to build a metal parent like metal

bone. The best candidates for cold welds are the non-ferrous metals. Carbon is a metal which can

not welded to ice.

Diffusion Welding

Diffusion bonding is a type of solid-state welding able to link dissimilar and similar

metals together. A widely seen phenomenon of solid-state welding where the atoms of two

metallic surfaces intersperse over time. Diffusion welding is usually performed at 50 to 70

percent of the absolute melting temperature of the welded materials.

Diffusion welding does not allow the metals to pass a liquid process and therefore does

not allow a metal filler. The weld itself has no additional weight, and the weld itself also shows

the temperature tolerance and strength of the welded metals. There is also very little plastic

deformation (to no) between the welds.

Diffusion welding is used to combine reactive and refractory metals, identical and

dissimilar metals as well as different thickness pieces of metal. This is usually used mainly

because of how unbelievably costly it is to execute the process for welding jobs which are

impractical or extremely difficult to weld by other means.

If you join metals with a common diffusion bonding mechanism, both metals are clamped

together with each other’s surface. You must machine all surfaces to a finish as smooth as

possible before welding. Not only that but you have to keep pollutants away from the weld as

well. Once you clamp the two metals, it is important to apply heat and pressure for several hours.

Using either electrical resistance or in a furnace one can heat both surfaces. Pressure can be

applied to the weld using a temperature hydraulic press which allows accurate load

measurements on both metal sections. By using metals that have a high oxide layer, diffusion

bonding must be achieves in either an inert-gas or a vacuum.

Unique Processes

The following is a list of unique processes (not all):

1. Thermit welding

2. Laser beam welding

Thermit Welding (TW)

Thermit Welding (TW) is a welding

process that employs molten metal to

permanently join the conductors. The process

employs an exothermic reaction of a thermite

composition to heat the metal, and requires no external source of heat or current. The chemical

reaction that produces the heat is an aluminothermic reaction between aluminum powder and a

metal oxide.

Properties of Thermit Welding:

An exothermic weld has higher

mechanical strength than other forms of weld, and

excellent corrosion resistance It is also highly

stable when subject to repeated short-circuit

pulses, and does not suffer from increased

electrical resistance over the lifetime of the installation. However, the process is costly relative to

other welding processes, requires a supply of replaceable moulds, suffers from a lack of

repeatability, and can be impeded by wet conditions or bad weather (when performed outdoors).

Advantages of Thermit Welding:

No external power source is required (heat of chemical reaction is utilized);

Very large heavy section parts may be joined.

Disadvantages of Resistance Welding:

Only ferrous (steel, chromium, nickel) parts may be welded;

Slow welding rate;

High temperature process may cause distortions and changes in Grain structure in the

weld region.

Weld may contain gas (Hydrogen) and slag contaminations.

What is Thermal Welding used for?

Exothermic welding is usually used for welding copper conductors but is suitable for

welding a wide range of metals, including stainless steel, cast iron, common steel, brass, bronze,

and Monel. It is especially useful for

joining dissimilar metals. The process is

marketed under a variety of names such as

Harger ULTRASHOT, American Rail

Weld, ERICO CADWELD, Quikweld,

Tectoweld, Ultraweld, Techweld, TerraWeld, Thermoweld, Ardo Weld, AmiableWeld, AIWeld,

FurseWeld, CADWELL TVT and Kumwell.

Laser beam welding

Laser beam welding (LBW) is a

welding technique used to join pieces of

metal or thermoplastics through the use

of a laser. The beam provides a

concentrated heat source, allowing for

narrow, deep welds and high welding

rates. The process is frequently used in

high volume applications using

automation, as in the automotive

industry. It is based on keyhole or

penetration mode welding.

Laser beam welding operates by using concentrated energy beams (or lasers) to heat the

surface of two or more materials at the desired joining point. Since laser beam welders amplify

light to create their source of heat energy, they can target hyperspecific areas using precise

energy controls. This makes laser beam welding ideal for a large range of welding scenarios,

including fine-detail and multipiece welding. Many types of laser welding equipment exist, and

each type offers specific advantages and disadvantages.

Advantages and Disadvantages of Laser Beam Welding

Laser welding offers a safer alternative to techniques like arc welding, but it comes with a

few drawbacks that may limit its use for some applications. Below, we've outlined some of the

main advantages and disadvantages of laser beam welding.

Advantages

Precision: Laser beam welding works with spot sizes as low as 0.2 mm, making it ideal

for small parts and detailed welding.

Cleanliness: Laser beam welding doesn't produce splatter, creating a safer and more

efficient welding process than other welding techniques.

Robotic: The laser beam welding apparatus can connect with robotics, allowing easy

automation of the welding process at rapid and accurate levels.

Open air: Unlike electron beam welding, workers can perform laser beam welding in

open-air environments instead of vacuum-sealed compartments.

Heating: Laser welding has a small heat zone, making it perfect for detailing and welding

small or fragile materials as well as equipment susceptible to heat distortion.

Quality: Laser beams typically have a cleaner and more consistent weld finish.

Hypercontrollable: Operators possess a high degree of control over laser beam intensity

and direction, especially with fiber lasers, making them perfect for automated or semi-

automated welding practices.

Disadvantages

Cost: Laser beam welding is more expensive than other welding techniques.

Penetration: Laser beam welding cannot penetrate materials as deeply as electron beam

welding, and beam size can only go as high as 19 mm depending upon the materials.

Reflectivity: Certain materials (such as aluminum and copper) can reduce the

effectiveness of laser beam welding because of their reflectivity.

What is Laser beam welding used for?

Laser beam welding has already drastically reshaped the welding industry. Lasers create

precise, controllable welds at a fraction of the environmental cost, and they operate with minimal

heat transfer and no splatter.

The conjoined functions of robotics and laser beam welding will help with large-volume

welds, and researchers are developing more cost-effective laser welding techniques for small

manufacturing shops as well. While laser beam welding will not supplant electron beam welding

and arc welding, it's already proving itself a viable alternative for a number of different

applications.

Conclusion

Advantages and disadvantages in welding mainly:

What are some of the most common welding processes and why?

Gas Metal Arc Welding (GMAW/MIG)

This style of welding is also referred to as Metal Inert Gas (MIG). It uses a shielding gas along the wire electrode, which heats up the two metals to be joined. This method requires a constant voltage and direct-current power source, and is the most common industrial welding process.  It has four primary methods of metal transfer:  globular, short-circuiting, spray and pulsed-spray.

Gas Tungsten Arc Gas Welding (GTAW/TIG)

Welding together thick sections of stainless steel or non-ferrous metals is the most common use for this method. It is also an arc-welding process that uses a tungsten electrode to produce the weld. This process is much more time consuming than the other three and much more complex.

Shielded Metal Arc Welding (SMAW)

With this particular type of welding, the welder follows a manual process of stick welding. The stick uses an electric current to form an arc between the stick and the metals to be joined.

This is often used in the construction of steel structures and in industrial fabrication to weld iron and steel.

Flux Cored Arc Welding (FCAW)

This was developed as an alternative to shield welding. The semi-automatic arc weld is often used in construction projects, thanks to its high welding speed and portability.

What is the strongest type of weld?

This is not as simple a question to answer as it may first appear. The best weld depends on the

base material in question and its final intended use. From TIG to Plasma Arc Welding, each

technique has its own unique advantages and disadvantages over the others. 

According to cromeld.com, the strongest type of weld could be stick welding: "if pure strength

that counts and the thickness of the material that can be welded, then stick welding is the winner.

As we said, the stick is the only one capable of welding cast iron and works on both dirty

materials and in harsh weather conditions."

But that doesn't necessarily mean stick welding is the best choice for all scenarios. "However,

MIG can be applied to many metals of varying thickness, while TIG produces the highest quality

welds, especially when it comes to thin metals."

It will also completely depend on the metal you wish to weld. Aluminum, for example, is a fairly

soft metal and can't cope with too much heat. For this reason, there are only two viable welding

techniques that can be used, MIG and TIG. 

Of these two techniques, TIG is widely considered to be the de-facto technique for best results. 

Steel, on the other hand, is a much beefier metal when compared to aluminum. For this reason,

it can take a lot more punishment before compromising its strength. But, which welding

technique provides the strongest weld depends on the thickness of the material.

MIG is generally considered to be the best technique for most steel applications. For thicker steel

sheets, many attest to the superiority of stick and flux welding.

If the steel is mild and stainless, TIG and MIG can be used without any real issues. 

What is the best welder for a beginner?

If you are new to the world of welding, some

techniques are much easier to pick up than

others. MIG welding, for example, is widely

considered to be the easiest to pick up and run

with. But why?

MIG is a welding technique that has high adjustability of power output. It also produces very

clean welds compared to other techniques. It is also great as it tends to be a pretty quick welding

technique to produce a good weld for beginners and master welders alike. 

Other techniques also exist if your budget allows. You could consider getting yourself something

called a hybrid welder. This lets you, as the name suggests, try multiple styles at once. Yet

despite this, many practicing welders attest to the simplicity and reliability of MIG welding to

learn the ropes. 

To conclude, the first machine tool services date back to 1200 BC, and the tools themselves were

handcrafted. Although today’s machine tools may not be handcrafted in the same manner,

welding allows craftsmanship to come into the world of modern machinery.

References

i. 4 Popular Types of Welding Procedures. (2019, October 31). Retrieved from

https://www.lincolntech.edu/news/skilled-trades/welding-technology/types-of-

welding-procedures

ii. Ramesh Singh. (2015) Thermit Welding. Retrieved from

https://www.sciencedirect.com/topics/engineering/thermit-welding

iii. Singh, R. (2012). Electron Beam Welding. Retrieved from

https://www.sciencedirect.com/topics/engineering/electron-beam-welding

iv. 4 Popular Types of Welding Procedures. (2019, October 31). Retrieved fro

https://www.lincolntech.edu/news/skilled-trades/welding-technology/types-of-

welding-procedures

v. What is Laser Welding and How Does it Work? (n.d.). Retrieved from https://www.twi-

global.com/technical-knowledge/faqs/faq-how-does-laser-welding-work

vi. Benefits of Fiber Laser Welding. (n.d.). Retrieved from

https://www.laserstar.net/en/products/manual-welding-fiber-lasers/benefits-of-

fiber-laser-welding/

vii. https://www.praxairdirect.com/Industrial-Gas-and-Welding-Information-Center/Welding-

Tips-Tricks-and-Information/Oxyacetylene-Welding.html

viii. https://gowelding.org/articles/introduction-welding/

ix. http://josefgases.com/oxy-fuel-welding/

x. https://www.twi-global.com/technical-knowledge/faqs/what-is-arc-welding

xi. https://www.wasatchsteel.com/advantages-disadvantages-arc-welding/

xii. https://www.aws.org/rwma/page/resistance-welding

xiii. https://www.swantec.com/technology/resistance-welding/

xiv. https://weldingclassesnearme.com/articles/what-exactly-is-solid-state-welding/