ME - Mechanical Engineering
Online Magazine for Mechanical Engineers

Atkinson cycle is an ideal cycle for Otto engine exhausting to a gas turbine. In this cycle the isentropic expansion 3-4 of an Otto cycle (1-2-3-4) is further allowed to the lowest cycle pressure so as to increase the work output. With this modification the cycle is known as Atkinson cycle. The cycle is shown on p-V and T-s diagrams.
P-vand T-s diagram for the air-standard Atkinson cycle
Pressure-volume and Temperature-entropy diagram for the air-standard Atkinson cycle
Thermal Efficiency of Atkinson cycle
thermal efficiency Atkinson Cycle efficiency Atkinson Cycle
Where, Compression ratio = rk = v1/ v2,
the expansion ratio = re = v4/v3
Electroslag welding (ESW) and its applications are similar to electrogas welding. The main difference is that the arc is started between the electrode tip and the bottom of the part to be welded. Flux is added, which then melts by the heat of the arc. After the molten slag reaches the tip of the electrode, the arc is extinguished. Heat is produced continuously by the electrical resistance of the molten slag. Because the arc is extinguished, Electroslag welding is not strictly an arc-welding process. Single or multiple solid as well as flux-cored electrodes may be used.
Equipment used for electroslag-Welding operations
Equipment used for electroslag-Welding operations
Electroslag welding is capable of welding plates with thicknesses ranging from 50 mm to more than 900 mm and welding is done in one pass. The current required is about 600 A at 40 to 50 Volts although higher currents are used for thick plates. The travel speed of the weld is in the range from 12 to 36 mm/min. Weld quality is high. This process is used for large structural-steel sections, such as heavy machinery, bridges, ships and nuclear-reactor vessels.
Eddy Parsons cars of the year for 2014.
Quickest away from the lights is regular autoexpress.co.uk reader and car fan Eddy Parsons, aged 11, from Hertfordshire. He’s compiled a brilliant list of his must have cars, plus a few special awards including family car, executive car, most annoying and innovative car of the year.

City Car

Citroen C - Funky styling and good value for money
Citroen C - city car of year 2014

Supermini

the Mini Hatch - remains at the top with classic looks and modern tech - the Cooper is outstanding.
the Mini Hatch

Small family car

Audi A3 - belies its age with stylish looks and a luxurious cabin.
Audi A3

Family car

Volkswagen Passat - stylish, classy and comes with a heap of tech.
Volkswagen Passat

Executive car

Mercedes C Class - beats 3 Series thanks to better styling, better value for money and better interior.
Mercedes C Class

Small SUV

Citroen C4 Cactus
Citroen C4 Cactus

Large SUV

Range Rover Sport
Range Rover Sport

Luxury Car

Mercedes S Class - it's forward thinking, luxurious, fast and has got loads of room.
Mercedes S Class

Electric car

BMW i3 - stylish and stunning - a car you had want even if you didn't know it was electric.
BMW i3

Supercar

BMW i8 - futuristic and brilliant, with a fantastic powertrain.
BMW i8

Most annoying car

G-Wiz 
G-Wiz

Most innovative car

Volvo XC90 - Packed with safety features and includes more advanced technology.
Volvo XC90
  • Electron Beam Machining (EBM) is a thermal process. Here a steam of high speed electrons impinges on the work surface so that the kinetic energy of electrons is transferred to work producing intense heating.
  • Depending upon the intensity of heating the work piece can melt and vaporize.
  • The process of heating by electron beam is used for annealing, welding or metal removal.
  • During EBM process very high velocities can be obtained by using enough voltage of 1,50,000 V can produce velocity of 228,478 km/sec and it is focused on 10 - 200 μM diameter. Power density can go up to 6500 billion W/sq.mm. Such a power density can vaporize any substance immediately.
  • Complex contours can be easily machined by maneuvering the electron beam using magnetic deflection coils.
  • To avoid a collision of the accelerating electrons with the air molecules, the process has to be conducted in vacuum. So EBM is not suitable for large work pieces.
  • Process is accomplished with vacuum so no possibility of contamination.
  • No effects on work piece because about 25-50μm away from machining spot remains at room temperature and so no effects of high temperature on work.
electron beam machining process
Schematic illustration of the electron beam machining process

MRR in EBM:

Q = area of slot or hole * speed of cutting = A*V
Where power for 'Q' MRR is P = C.Q
Where,
C = Specific power consumption
Thermal velocity acquired by an electron of the work material due to EB is
Electron Beam thermal velocity
Where, Kb = Boltzmann constant
M = mass of one atom of work.
T = rise in temperature

Advantages:

  • Very small size holes can be produced.
  • Surface finish produced is good.
  • Highly reactive metals like Al and Mg can be machined very easily.

Limitations:

  • Material removal rate is very low compared to other convectional machining processes.
  • Maintaining perfect vacuum is very difficult.
  • The machining process can't be seen by operator.
  • Workpiece material should be electrically conducting.

Applications:

  • Used for producing very small size holes like holes in diesel injection nozzles, Air brakes etc.
  • Used only for circular holes.
  • Water Jets alone (without abrasives) can be used for cutting. Thin jets of high pressure and high velocity have been used to cut materials such wood, coal, textiles, rocks, concrete, asbestos.
  • The mechanism of material removal rate is by erosion. When high pressure water jet emerges of a nozzle, it attains a large kinetic energy.
  • High velocity jet strikes the work piece, its kinetic energy is converted into pressure energy including high stresses in the work material.
  • When the induced stress exceeds the ultimate shear stress of the material, rupture takes place.
Water Jet Machining
Schematic illustration of water jet machining

Characteristics of Water Jet Machining (WJM):

  • The pressures normally used in WJM are 1500 to 4000 MPa.
  • Nozzle is made by sintered diamond and exit nozzle is about 0.05 to 0.35 mm.
  • No moving parts in the system, so less operating and maintenance costs and safe process.
  • No thermal damage to work and intricate shapes can be cut.
  • The process is convenient for cutting soft and rubber like materials because teeth will get clogged in conventional methods.

Limitations of Water Jet Machining:

  • Initial setup cost for Water Jet Machining process is very high and hard materials cannot be cut.
  • Cutting of hard materials have been over come by introducing abrasives in water in WJM also called Abrasive Water Jet Machining (AWJM).
In AWJM abrasives below 0.45 micron size is mixed with water and compressed to 420 MPa with this machine a 25 mm thick Al has been cut for 100 mm/min.
On zinc-nickel steel of 25mm thick the rate of cutting is 35.5 mm/min, but on the same work EDM can cut 2.5 mm/min.
Gas Tungsten-arc Welding (GTAW) formerly known as TIG (Tungsten Inert Gas) welding, the filler metal is supplied from a filler wire as shown in figure below. Because the tungsten electrode is not used during this welding operation, a constant and stable arc gap is maintained at a constant current level. The filler metals are similar to the metals to be welded and flux is not used. The shielding gas used in this welding process is usually argon or helium (or a mixture of these both gases). Welding with gas tungsten-arc welding may be done without using filler metals. for example, in the welding of close-fit joints.
Gas Tungsten-arc welding
gas tungsten-arc welding process
Depending on the type of metals to be welded, the power supply is either DC at 200A or AC at 500A (see below image). In general, AC is preferred for welding metals aluminium and magnesium, because the cleaning action of AC removes oxides and improves weld quality. Thorium or zirconium can be used in the tungsten electrodes to improve their electron emission characteristics. The power supply ranges from 8 to 20 kW. Contamination of the tungsten electrode by the molten metal can be a major problem, particularly in critical applications, because it can cause discontinuities in the weld. Contact of the electrode with the molten-metal pool should be avoided.
Equipment for gas tungsten-arc welding
Equipment for gas tungsten-arc welding operations
The gas tungsten-arc welding process is used for a wide variety of applications and metals, particularly aluminium, magnesium, titanium and the refractory metals. It is highly suitable for thin metals. The cost of the inert gas makes this process more expensive than Shielded Metal-arc Welding but provides welds of very high quality and surface finish. The equipment used for gas tungsten-arc welding process is portable.
Metal forming is a manufacturing process in which forces are applied on raw material such that stresses induced in the material are greater than yield stress and less than ultimate stress.
The material experiences plastic deformation to change the shape of the component and converted to the desired shape of the component.
Forming process can be broadly classified into two types as cold working and hot working.

1. Cold Working:

Deforming the material at a temperature below the recrystallization temperature of the work metal is called cold working. In cold working process,strength and hardness increases due strain hardening, but ductility decreases. Good surface finish and high dimensional accuracy are achieved. If cold working is higher than certain limits, the metal will fracture before reaching the desired shape and size. Usually cold working operations are performed in many steps with intermediate annealing operation.

2. Hot Working:

Deforming the material at a temperature higher or equal to the recrystallization temperature of the work metal is called hot working. In hot working, refinement of grain size occurs, thus, improving mechanical properties. Even a brittle material can be hot worked. This requires much less force for deformation, but the finally formed surface finish and dimensional accuracy are not goog. There is no work hardening.

Advantages of Metal Forming Process:

  • The amount of wastage of metal during metal forming process is negligible.
  • Grain orientation is possible.
  • Because of grain orientation the material is converted from isotropic to anisotropic material.
  • In most of engineering applications it requires anisotropic material.
  • Sometimes the strength and hardness of work material is increasing.
  • Some other metal forming process, the surface finish obtained on the component is very good and excellent.

Disadvantages of Metal Forming Process:

  • Higher mount of force and energy is required for metal forming process compared to other manufacturing methods.
  • Except the forging operation, all other metal forming process are used for producing uniform cross sectioned components only.
  • The components with cross holes cannot be produced easily using metal forming process.
Casting is also known as foundering, is the oldest manufacturing process in which liquid molten metal is poured into a perforated casting cavity of refractory material. Allow liquid metal to solidify, after solidification the casting metal can be taken out by breaking the mould. Casting process is used to produce components such as pistons, mill rolls, wheels, cylinder blocks, liners, machine tool beds.
Casting process

Advantages of casting:

  • Molten metal flows into ant small section in molten cavity, hence any complex shape can be easily produced.
  • Practically any type of material can be casted.
  • Ideal method is by producing small quantities
  • Due to small cooling rate from all directions, the properties of casting are same in all directions.
  • Any size of casting can be produced like up to 200 tonnes.
  • Casting is the often cheapest and most direct way of producing a shape with certain desired mechanical properties.
  • Certain metals and alloys such as highly creep resistant metal-based alloys for gas turbines cannot be worked mechanically and can be cast only.
  • Heavy equipment like machine leads, ship’s propeller etc. can be cast easily in the required size rather than fabricating them by joining several small pieces.
  • Casting is best suited for composite components requiring different properties in different direction. These are made by incorporating preferable inserts in a casting. For example, aluminium conductors into slots in iron armature for electric motors, wear resistant skins onto shock resistant components.

Limitations of casting:

  • With normal sand casting process the dimensional accuracies and surface finish is less.
  • Defects are unavoidable.
  • Sand casting is labor intensive.
A refrigerant is a substance or mixture, usually a fluid, used in a heat pump and refrigeration cycle that can extract heat from another body or substance. Ice, cold water, cold air etc. can be treated a refrigerants.

Desired properties of Refrigerants:

1. Vapor density:
To enable use of smaller compressors and other equipment the refrigerant should have smaller vapor density.
2. Enthalpy of vaporization:
To ensure maximum heat absorption during refrigeration, a refrigerant should have high enthalpy of vaporization.
3. Thermal Conductivity:
Thermal conductivity of the refrigerant should be high for faster heat transfer during condensation and evaporation.
4. Dielectric strength:
In hermetic arrangements, the motor windings are cooled by refrigerants vapor on its way to the suction valve of the compressor. Therefore, dielectric strength of refrigerant is important property in hermetically sealed compressor units.
5. Critical temperature:
In order to have large range of isothermal energy transfer, the refrigerant should have critical temperature above the condensing temperature.
6. Specific heat:
To have minimum change in entropy during the throttling process, the specific heat should be minimum. For this, liquid saturation line should be almost vertical.
7. Leak tendency:
The refrigerant may leak out of the system. The problems with leakage are wearing out of joint or the material used for the fabrication of the system.  A denser refrigerant will have fewer tendencies to leak as compared to higher density refrigerant. Moreover the detection of leaks should be easy to loss of refrigerant. Leakage can be easily identified if the refrigerant has distinct color or odour.
8. Toxicity:
The refrigerant used in air conditioning, food preservation etc. should not be toxic in nature as they will come into contact with human beings. refrigerants will affect human health if they are toxic.
9. Cost of refrigerants:
The quantity of refrigerant used in any industry is very small. Therefore cost of the refrigerants is normally high when compared to other chemicals.  Similarly if it is very low industry professional will not take necessary action to control the leaks. Air is very safe refrigerant which is available free of cost.
10. Availability:
Refrigerants should be readily available near the usage point. It must be sourced and procured within a short span of time to enable the user in case of leaks, maintenance schedules etc.
desired properties of a refrigerant

Properties of commonly used Refrigerants:

1. Carbon dioxide: 

Carbon dioxide is widely as refrigerant in mechanical systems refrigerant, marine services, hospitals etc. due to its excellent safety properties. It is odourless, non-toxic, non-flammable, non-explosive and non-corrosive.

2. Sulphur dioxide:

Sulphur dioxide was widely used as refrigerant during early 20th century. However its use has been restricted now-a-days because of its many inherent disadvantages. It is highly toxic, non-flammable, non-explosive, non-corrosive and works at low pressures

3. Ammonia:

Ammonia is one of the earliest type of refrigerants which is still widely used in many applications due to its inheritance excellent thermal properties, It is toxic in nature, flammable explosive under certain conditions, it has low specific volume¸ high refrigerating effect, low piston displacement in case of reciprocating compressors make it an ideal refrigerant for cold storage's, ice plants, packing plants, skating rinks breweries etc.

4. Freon-11:

Freon-11 (Trichloro fluoromethane) is used under low operating pressures; it is non-toxic, non-corrosive and non-flammable. Due to low operating pressure and high displacement, it is used in systems employing centrifugal compressors. It is used for air-conditioning applications.

5. Freon-12:

Freon-12 (Dichloro difluoromethane) is non-flammable, non-toxic and non-explosive. It is highly chemically stable. If it is brought in contact with open flame or heater elements, it decomposes into highly toxic constituents. It has not only excellent safe properties but also condenses at moderate pressure under normal atmospheric conditions.

6. Cryogenic refrigerants:

Cryogenic refrigerants are those refrigerants which produce minus temperature in between range -157degree centigrade to -273degree centigrade in the refrigerated space. The cryogenic refrigerants have exceptionally low boiling point at atmospheric pressure. Some of the widely used cryogenic refrigerants are Helium, Nitrogen, Oxygen, Hydrogen.
Electrogas welding (EGW) is an vertical positioned arc welding process, is used for welding the edges of sections vertically and in one pass with the pieces placed edge to edge (butt joint). It is classified as a machine-welding process, because for its operation requires special equipment. The weld metal is deposited into a weld cavity between the two pieces to be joined. The space is covered by two water-cooled copper dams(shoes) to prevent the molten slag from running off; mechanical drives move the shoes upward.
electrogas welding process
Schematic illustration of the electrogas welding process.
One or more electrodes are fed through a conduit and a continuous arc is maintained by flux-cored electrodes at up to 750 A or solid electrodes at 400 A. Power requirements is 20 kW. Shielding is done by means of an inert gas, such as argon or helium depending on the type of material being welded. The gas may be provided either from an external source, from a flux-cored electrode or from both the sources. The equipment of electrogas welding is reliable and training an operator is easy. Weld thickness is between 12 mm to 75 mm on steels, titanium and aluminum alloys.
Electrogas welding process is used in the construction of bridges, pressure vessels, thick-walled and large-diameter pipes, storage tanks, submarines and ships.
In Plasma-arc Welding (PAW) is an arc welding process, a concentrated plasma arc is produced and directed towards the weld area. The arc is stable and reaches temperatures as high as 33,000°C. A plasma is an ionised very hot gas composed of nearly same numbers of electrons and ions. The plasma starts between the tungsten electrode and the orifice by a low current pilot arc. What makes plasma-arc welding unlike other processes is that the plasma arc is concentrated because it is forced through a relatively small orifice. Operating currents usually are less than 100 A. When a filler metal is used it is fed into the arc as is done in Gas Tungsten-arc Welding. Arc and weld-zone shielding is supplied by means of an outer-shielding ring and the use of inert gases like argon, helium or mixtures.
There are two methods of plasma-arc welding:
  • In the transferred-arc method of plasma-arc welding(in pic left side), the workpiece being welded is part of the electrical circuit. The arc transfers from the electrode to the work piece hence the term transferred.
  • In the non transferred-arc method of plasma-arc welding(in pic right side), the arc occurs between the electrode and the nozzle and the heat is carried to the workpiece by the plasma gas. This thermal-transfer mechanism is similar to that for an oxy-fuel flame.
Plasma-arc Welding (PAW)
Two methods of plasma-arc welding processes (a) transferred and (b) non transferred
Compared to other arc welding processes, Plasma-arc Welding process has better arc stability, less thermal distortion and higher energy concentration, thus permitting deeper and narrower welds. PAW has higher welding speed ranges from 120 mm/min to 1000 mm/min. A variety of metals can be welded with part thicknesses less than 6 mm.
The high heat concentration can penetrate completely through the joint with thicknesses as much as 20 mm for some titanium and aluminium alloys. In the keyhole technique, the force of the plasma arc displaces the molten metal and produces a hole at the leading edge of the weld pool. Plasma-arc welding often is used rather than Gas Tungsten-arc welding for butt and lap joints because of its higher energy concentration, better arc stability and higher speed of welding. Proper training and skill are required for operator who works on this equipment.
The flux-cored arc welding process is shown in image below is similar to Gas Metal-arc Welding, except that the electrode is tubular in shape and is filled with flux. Cored electrodes produce a more stable arc, improve weld contour, and produce better mechanical properties of the weld metal. The flux in these electrodes is much more flexible than the brittle coating used on Shielded Metal-arc Welding electrodes, so the tubular electrode can be provided in long coiled lengths.
Flux-cored Arc Welding
Schematic illustration of the flux-cored arc-welding process.
The electrodes used in this welding process are usually 0.5mm to 4 mm in diameter and the power required is about 20 kW. Self-shielded cored electrodes also are available. They do not require any external shielding gas, because they contain emissive fluxes that shield the weld area against the surrounding atmosphere. Small diameter electrodes have made the welding of thinner materials not only possible but often preferable for using. Also small diameter electrodes make it relatively easy to weld joints in different positions and the flux chemistry permits the welding of many metals.
The Flux-cored arc Welding process combines the versatility of Shielded Metal arc welding with the continuous and automatic electrode feeding feature of gas metal-arc welding. The process is economical and versatile, so it is used for welding a variety of joints, mainly on steels, stainless steels, and nickel alloys. The higher weld metal deposition rate of the flux-cored arc welding process has led to its use in the joining of sections of all thicknesses. The use of tubular electrodes with very small diameters has extended the use of this process to work pieces of smaller section size.
A main advantage of using flux-cored arc welding is the ease with which specific weld-metal things can be developed. By adding alloying elements to the flux core, virtually any alloy composition can be produced. The process is easy to automate and is readily adaptable to flexible manufacturing systems and robotics.
The common rail is the most essential component of the direct fuel injection system.
Common Rail
Its role consists in accumulating highly pressurized fuel and distributing it to the injectors. The next-generation diesel and gasoline engines tend to become smaller and lighter for less fuel consumption and better performance, which increases the fuel pressure. This makes out of the common rail a component with very specific requirements. It should possess best mechanical properties in order to be strong and resistant to fatigue, loading, vibration and other environmental conditions.
Eventual common rail failure is always critical since the entire vehicle can be blocked or even set on fire. Exposed continuously to increased pressure and heat, its performance is crucial for the whole system.  Most common rail problems are related to the complex geometry of the components and possible cracks caused by material fatigue or during the manufacturing process. Therefore a special attention should be paid to the following: defining and keeping best parameters in the design phase, selecting high-quality resistant steels and excellent expertise in the forging manufacturing process. Following these guidelines guarantees perfection and reliable performance of the entire fuel direct injection.
Special attention should be paid to:
1. Design
The early stage of common rail’s development is essential for the later performance of that component. The right geometry and precise parameters prevent a lot of problems that occur later as defects in heading process or material fatigue. For example, modern gasoline engines are smaller and lighter which increases fuel internal pressure and requires common rails with complex shape. Hot forging offers a vast variety of shapes and sizes that can be achieved with high-quality equipment as forging hammers, mechanical presses, screw presses and other tools. Defining end-of-forging temperature, cooling and trimming parameters are also highly significant for most precise geometry.
2. Best material selection
The common rail itself acts as a common fuel storing rail and it is permanently exposed to heat and pressure.  Therefore, if the raw materials haven't been selected wisely, quality problems can occur. The most common rail problems related to material selection are shorter product life and reduced fuel accumulation volume.
3.  Strength
When forged, the common rail is made of stainless steel and consists only of one piece which eliminates the risk for cracks and leakages. Additionally, forging strengthens the material by closing empty spaces within the metal while deforming and shaping it with localized compressive forces.

Every single production step of the common rail manufacturing process should undergo strict control. The manufacturing company should provide best design expertise, develop most resistant materials, use 100% controlled tools and apply best forging techniques.
Shielded Metal-arc Welding (SMAW) is the simplest and used for many joining processes. More than 50% of industrial and maintenance welding currently is performed by this welding process. In this welding operation electric arc is generated by touching the tip of a coated electrode against the workpiece and withdrawing it quickly to a distance sufficient to maintain the arc as shown in picture below. The electrodes are in the shapes of thin, long rods that are held manually. The heat generated melts a portion of the electrode tip, its coating and the base metal in the immediate arc area. The molten metal consists of a mixture of the base metal, the electrode metal, and substances from the coating on the electrode, this mixture forms the weld when it solidifies. The electrode coating de-oxidizes the weld area and provides a shielding gas to protect it from oxygen in the surroundings. A bare section at the end of the electrode is clamped to one terminal of the power source, while the other terminal is connected to the workpiece being welded. The current, which may be either DC or AC usually in the range 50A to 300 A.
Schematic illustration of the shielded metal-arc welding process.
For sheet-metal welding, DC is suitable because of the steady arc it produces. Power requirements generally are less than 10 kW.
A deep weld showing the buildup sequence of eight individual weld beads.
The Shield Metal-arc Welding process has the advantages of being relatively simple and requiring a smaller variety of electrodes. The equipment consists of a power supply, cables, and an electrode holder. The Shield Metal-arc Welding process commonly is used in general construction, shipbuilding, pipelines and other maintenance work. It is mainly useful for work in remote areas where a portable fuel-powered generator can be used as the power supply. Shield Metal-arc Welding is suited for workpiece of thickness 3 to 19 mm, although this range can be extended easily by skilled operators using multiple-pass techniques as shown in picture. The multiple-pass approach requires that the slag be removed after each weld bead. Unless removed fully, the solidified slag can cause severe corrosion of the weld area and lead to failure of the weld but it also prevents the fusion of welded layers. Before applying another weld, the slag should be removed completely by using wire brushing or weld chipping.
In Submerged-arc Welding (SAW), the weld arc is shielded by a granular flux consisting of lime, silica, manganese oxide, calcium fluoride and other compounds. The flux is fed into the weld zone from a hopper by gravity flow through a nozzle. The thick layer of flux completely covers the molten metal. Covered flux prevents spatter and sparks and suppresses the intense ultraviolet radiation and fumes characteristic of the Shield Metal-arc Welding (SMAW). Process. The flux acts as a thermal insulator by promoting deep penetration of heat into the workpiece.
The consumable electrode is a coil of bare round wire 1.5 mm to 10 mm in diameter, consumable electrode is fed automatically through a tube. Electric currents typically range from 300 A to 2000 A. The power supplies usually are connected to standard single-phase or three-phase power lines with a primary rating up to 440 V.
Submerged arc-welding process and equipment used
Schematic illustration of the submerged arc welding process and equipment. Unfused flux is recovered and reused
The flux is gravity fed, the SAW process is limited largely to welds in a flat or horizontal position having a backup piece. Circular welds can be made on pipes and cylinders-provided that they are rotated during welding. As image shows, the unfused flux is recovered, treated and reused. SAW is automated and is used to weld a variety of carbon and alloy steel and stainless-steel sheets or plates at speeds as high as 5 m/min. The quality of the Weld is very high with good toughness, ductility and uniformity of properties. The Submerged Arc Welding  process provides very high welding productivity, depositing 4 to 10 times the amount of Weld metal per hour as the Shielded Metal-arc Welding process. Typical applications include thick-plate welding for shipbuilding and for pressure vessels.
Now-a-days it is a common practice for different clubs, departments, businesses, colleges and schools to have their own customize t-shirts. Having a custom t-shirt for a group is one way of identifying if a person studying/working in a particular group or is a member of any specific organization.
A customized t-shirt talks a lot regarding your character, your job position and reflects the fashion style in you. You can find many online stores where you can make the customized t-shirt design and you can make a purchase.
Mechanical Engineering - The profession for Intelligent people t-shirt design

ME - Mechanical Engineering shirt design


white plain mechanical engineering t-shirt


I do all my own stunts shirt design

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peace and love mechanical engineering shirt design
These pictures are some of the decent t-shirt designs found while surfing the web.
Gas metal-arc welding (GMAW) also called as metal inert-gas (MIG) welding, In Gas metal-arc welding process the weld area is shielded by an effectively inert atmosphere of argon, helium, carbon dioxide or various other gas mixtures. The consumable bare wire is fed automatically through a nozzle into the Weld arc by a wire-feed drive motor. In addition to using inert shielding gases, de-oxidizers usually are present in the electrode metal itself in order to prevent oxidation.
Basic equipment used in gas metal arc welding operation
Basic equipment used in gas metal arc welding operation
Gas Metal Arc Welding process, formerly known as metal inert gas
Gas Metal Arc Welding process, formerly known as Metal Inert Gas
The temperatures generated in Gas metal-arc welding are low, GMAW method is suitable only for thin sheets and sections of less than 6 mm, otherwise incomplete fusion may occur. GMAW operation is easy to perform is commonly used for welding ferrous metals in thin sections. Pulsed-arc systems are used for thin ferrous and nonferrous metals. GMAW process is used for welding most ferrous and nonferrous metals and is used extensively in the metal-fabrication industry. Because of the relatively simple nature of the process, the training of operators is easy. This process is versatile, quick, economical and welding productivity is double that of the Submerged-arc Welding process.
Otto cycle consists of two isoentropic and two isochoric processes. Heat is supplied and heat is rejected by the cycle during isochoric process.
p-V and T-s diagram diagram for the air-standard otto cycle
Pressure-volume and Temperature-entropy diagram for the air-standard otto cycle
Where,
1-2: Adiabatic compression
2-3: Isochoric heat addition
3-4: Adiabatic expansion
4-1: Isochoric heat rejection

Heat supplied during constant volume process 2-3
Heat supplied by the air during constant volume
Heat rejected during constant volume process 4-1
Heat rejected by the air during constant volume
The thermal efficiency of otto cycle can be written as
thermal efficiency of otto cycle
Stirling cycle consists of two isothermal and two isochoric processes. Heat rejection and heat addition takes place at constant temperature.
p-V and T-s diagram for the stirling cycle
Pressure-volume and Temperature-entropy diagram for the air-standard stirling cycle
Where,
1-2: Isothermal expansion
2-3: Constant volume cooling
3-4: Isothermal compression
4-1: Contant volume heating

From the p-V and T-s diagram of stirling cycle it is clear that the amount of heat addition and heat rejection during constant volume is same.

Heat supplied = Work done during isothermal expansion
Heat supplied in stirling cycle
Heat rejected by the air during isothermal compression
Heat rejected in stirling cycle
Work done = heat supplied - heat rejected
Efficiency of stirling cycle can be written as 
  Efficiency of stirling cycle
Welding joints
There are five types of welded joints for bringing two parts together for joining.
Five types of welded joints are butt joint, corner joint, lap joint, tee joint and edge joint.


Butt joint:

In Butt welded type, the parts lie in the same plane and are joined at their edges.

Corner joint:

The parts in a corner joint form a right angle and are joined at the center of the angle.

Lap joint:

Lap joint consists of two overlapping parts.

T joint:

In a T joint, one joint is right angle to the other joint in the approximate shape of the letter "T".

Edge joint:

The parts in edge joint are parallel with at least one of their edges in common and the joint is made at the common edge(s).

butt joint, corner joint, lap joint, T joint and edge joint