ME - Mechanical Engineering


Online Magazine for Mechanical Engineers

The animated infographic of how a four-stroke Otto-cycle engine works.
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A Hammer is a mechanical tool that delivers a sudden impact to an object. Commonly hammers are used to drive nails, fit parts, forge metal and break apart objects. There are different types of Hammers, They vary in shape, size and structure. Here 23 different types of hammers pictures are shown below.

Brick Hammer
Brick Hammer

The chisel side scores a line around a brick. The brick hammer can break the brick in two parts.

Traditional curved-claw Hammer
Traditional curved-claw Hammer
Traditional curved-claw Hammer drives nails well and removes nails easily with the rocking action of its curved claw.

Body mechanic's Hammer
Body mechanic's Hammer
Body mechanic's hammer is used along with a small curved anvil called a dolly to remove dents from car panels.

Lineman's Hammer
Lineman's Hammer
Lineman's hammer is best suited to driving big lag screws and hammering bolts in utility-pole work.

Chasing Hammer
Chasing Hammer
Chasing hammers are designed and shape metal jewelry.

Titanium framing Hammer
Titanium framing Hammer
Titanium framing hammer has a titanium body with a sixteen-inch handle for maximum nail-extracting leverage.

Solid-steel framing Hammer
Solid-steel framing Hammer
Solid-steel framing Hammer is one-piece forged-steel design resists breakage and the waffle-pattern face grips nails.

Welder's Hammer
Welder's Hammer
Welder's hammer has weird-looking spring helps handle increases comfort and dissipates heat.

Ball-peen Hammer
Ball-peen Hammer
Ball-peen hammer can be used to shape the head of a rivet or reach into small recesses.

Tinner's Hammer
Tinner's Hammer
Tinner hammers are sharpened cross-peen can complete a folded seam or set a rolled edge.

Prospector's Hammer
Prospector's Hammer
Prospector's hammer has the head breaks rocks apart and the pick splits them cleanly along existing cracks.

Electrician's Hammer
Electrician's Hammer
Electrician's Hammer has a long-necked that helps electricians drive nails at hard places.

Drywall Hammer
Drywall Hammer
Chops errant bits of drywall and sets nails without breaking through walls' paper faces.

Toolmaker's Hammer
Toolmaker's Hammer
Toolmaker hammer is used for delicate work in the machine shop. The hole in the head has a magnifying glass.

Soft-face Hammer
Soft-face Hammer
Soft-face hammer is used to bend metal, wood, plastic or composite, When the surface must not be damaged.

Tack Hammer
Tack Hammer
Tack hammer has the split end of the head is, essentially, a horseshoe magnet for holding nails in place.

Dead-blow Hammer
Dead-blow Hammer
Dead-blow Hammer has an iron fist in a velvet glove. A non marring hammer that hits with tremendous force.

Railroad-spike maul Hammer
Railroad-spike maul Hammer
Railroad-spike maul Hammer is used for driving a railroad spike into a creosote-soaked tie.

Stone sledge Hammer
Stone sledge Hammer
Stone sledge Hammer is generally used for breaking giant rocks.

Blacksmith's sledge Hammer
Blacksmith's sledge Hammer
Blacksmith's sledge hammer is designed for shaping a bar of white-hot steel.

Sledge Hammer
Sledge Hammer
Sledge Hammer is best employed to drive wedges or knock rigid assemblies together or apart.

Bushing Hammer
Bushing Hammer
Bushing hammer looks like a three-pound meat tenderizer, but this adds a rough texture to stone.

Half-hatchet Hammer
Half-hatchet Hammer
Half hammer, half hatchet can be used for many purposes.

All 23 Hammers Image Courtesy: Popular Mechanics
Watt linkage is also known as the parallel linkage. Watt mechanical linkage was invented by James Watt. In Watt's linkage central moving point of is constrained to travel on an approximation to a straight line. Watt's Linkage can be found in some automobile vehicles at suspensions that allows the axle of a vehicle to travel vertically while preventing sideways motion.
Animation of Watt Linkage Mechanism

Application of Watt's Linkage:

Watt's linkage mechanism is used in the rear axle of some car suspensions as an improvement over the Panhard rod. These mechanism is used to prevent relative sideways motion between the axle and body of the car. It approximates a vertical straight line motion more closely and does so while locating the centre of the axle rather than toward one side of the vehicle, as commonly used when fitting a Panhard rod.
Panhard rod consists of two horizontal rods of equal length mounted each side to the wheels of automobile. At center of Panhard rod, a vertical bar is connected. The center of this vertical rod the point which is constrained to move in a straight line motion is mounted to the center of the axle. All pivoting points are free to rotate in a vertical plane.
Watt's Linkage Rear Suspension
Watt’s linkage can be seen in the rear suspension of above animation as two Panhard rods mounted opposite each other.
The Word's Biggest Aircraft is Airlander 10. It is a 300 feet long.
Airlander 10
Part blimp, part plane, part helicopter of Airlander 10 was originally created by British design company Hybrid Air Vehicles for military surveillance by the U.S. Army.
Airlander 10 world's lagest aircraft
This aircraft is named as Airlander 10 because it can carry weight of 10 tons, It is made of a bespoke fabric of carbon fiber, kevlar and mylar, while the pressure of the helium inside maintains the aircraft's shape.
To get off from the ground Airlander 10 uses 325 Hp V8 diesel engines, that power the propellers; the cockpit is designed for one pilot and one observer.
Ring clock jewelry
Ring Clock gives us the time on hand fingers. This is a beautiful marriage of the ring and the watch.
Ring Clock gives time on hands.

Technical specifications of Ring clock:

Materials - For making this Ring Clock Stainless steel material is used for jewelry and watches with 316L being the type commonly used for such applications.
LED Lights - An LED lamp is a solid-state lamp that uses light-emitting diodes (LEDs) as the source of light. LED lamps offer long service life and high energy efficiency.
Wireless charging - Qi is an interface standard developed by the Wireless Power Consortium for inductive electrical power transfer over distances of up to 4 cm.
Water-resistant - Suitable for everyday use. Splash/rain resistant. NOT suitable for showering, bathing, swimming, snorkelling, water related work and fishing.
Energy saving - Automatic turn off after 1 minute. Our next task is to allow the rotation kinetic energy to give the power to the LED lights meaning that the next version of Ring Clock can be fully environmentally friendly.
Ring clock time display

Specification of prototype:

Ring body material: 316L surgical stainless steel (allergy free)
Light source: 144 energy safe ultra thin mono-color LED
Light color: blue or orange LED (optional)
Lighting time: displays for 1 minute after the rotation of the ring
Battery specification: 6 mAh, ultra thin rechargeable lithium polymer battery
Running time: 1 week with normal use (15 times activation per day) or 2 hours constant use

Ring Clock Dimensions:

Width: 14 mm
Thickness: 3-3.5 mm
Size (inside diameter): 15.7-23.8 mm

The air-standard Brayton cycle is a theoretical cycle for gas turbines. Brayton cycle consists of two reversible adiabatic or isentropic processes and two constant pressure processes.
The Brayton cycle represented on p-V and T-s coordinates. Brayton cycle is similar to Diesel cycle in compression and heat addition. The isentropic expansion of Diesel cycle is further extended followed by constant pressure heat rejection.
p-V and T-s diagram diagram for the air-standard brayton cycle
Pressure-volume and Temperature-entropy diagram for the air-standard Brayton cycle
Where,
1-2: Isentropic process
2-3: Isobaric process
3-4: Isentropic Process
4-1: Isobaric process

Thermal Efficiency of Brayton Cycle can be calculated by the formula
Brayton cycle efficiency
Where k is the specific heat ratio Cp/Cv.

A handgun is a weapon generally used for security purpose. Guns are designed to discharge projectiles (bullets) depending upon the amount of velocity need. Projection shot (bullet) by gun varies according to design but is usually effected by the action of gas pressure, either produced through the rapid combustion of a propellant or compressed and stored by mechanical means.
The purpose of a handgun is to kill people or animals.
Handgun parts
Image Via:gatech.edu


Checkout few Animations of Gun:
Handgun working
GIF Source: noble-empire.com

gun fire shot gif
GIF Source: imgur.com

In abrasive-jet machining (AJM) material is removed by the impact of a high velocity stream of gases and abrasive mixture focused on to the workpiece. High Velocity impact of an abrasive particle causes a tiny brittle fracture on the work surface and the flowing gases carries away the dislodged small workpiece particle.
Abrasive-jet Machining (AJM) process is similar to convectional sand blasting, but differs in the way that the abrasive is much finer and the process parameters are effectively controlled.
Abrasive-jet Machining (AJM) process

Features of Abrasive-jet Machining:

  • Size of abrasive particle is in the range from 10 to 50 µm.
  • Mechanism of material removal is due to brittle fracture by impinging abrasive grains at high speed.
  • This process is more suitable when the work material is brittle and fragile.
  • Normally number of grains per unit time is 2 to 20 g/min with non recirculation type and size of grains is 15 to 20µm.
  • Pressure of air/gas normally used is 2 to 10 MPa.
  • Nozzle is made by WC with orifice area of 0.05 to 0.2 sqmm and its life is 12 to 300 HR.
  • Material removal rate in abrasive jet machining process

MRR characteristics curve in AJM:

  • Nozzle is generally having contact with abrasives, so it should be made by very hard material to avoid wear.
  • Shape of orifice is circular or rectangular.
  • Nozzle tip distance is the distance between nozzle tip and work piece, it affects not only the MRR but also shape and size of cavity produced.
  • As the nozzle lip distance increases velocity of abrasive particles impinging on work surface increases due to their acceleration after they leave the nozzle, which in turn increases the MRR.
  • But with further increase in nozzle tip distance velocity decreases due to drag of the atmosphere.

Limitations:

  • Low MRR (40 mg/min) embedding of abrasive in work piece, tapering of drilled holes.
  • Tapping is about 7 degree if nozzle top distance is 15 mm.

Applications:

  • AJM is used for cutting, cleaning and for machining of semi-conductors such as silicon, gallium or germanium, for making holes and slots in glass, quartz, mica and ceramics.
  • A dimensional tolerance of 0.05 mm can be obtained with surface finish of 0.5 to 1.2 µm.
In soldering and brazing processes, the metal parts being joined are heated but not melted and molten filler material is made to flow between the two closely placed adjacent surfaces by the capillary action. A strong joint between the parts is formed on cooling to room temperature by the bond formed at the high temperature between the parent metal atoms and the filler metal atoms. These process are suitable for joining the dissimilar metals also.

Soldering

The American Welding Society (AWS) defines soldering as a joining process that takes place below 840°F, most of the brazing operations are done at temperatures ranging from 350 to 600°F.
Soldering is a metal joining process is used for making low mechanical strength joints. The Filler metal used has a low melting point and is called solder.
For metallic surface to be soldered, surface must be capable of being wetted by the solder. There must be liquid solubility between the solder and one or more of the constituents metals of each part to wet a surface. The atoms of at least one of the component metals of each part to wet a surface. The atoms of at least one of the component metals of the solder may form a solid solution with the metal being soldered but combination of two metals from the liquid solution may result in the formation of intermetallic compound.
The ability of joining solder to wet a surface depends on the cleanliness of the metallic surface. After cleaning, an extremely thin film of metallic oxide immediately forms on most of the metallic surfaces and inhibits its wetting by solder. Flux is used to dissolve the oxide film and also to protect the metallic surfaces thus uncovered until it has been effectively wetted by the solder.
In soldering joining process, the heat is supplied to the joint by soldering iron. The soldering iron may be heated electrically or by other means. The function of soldering iron is to heat the joint. The flat face of the soldering iron is held directly against the joint assembly so that the heat is transferred effectively to the parts being soldered.
Simple soldering joint
In soldering joining process, the heat is supplied to the joint by soldering iron. The soldering iron may be heated electrically or by other means. The function of soldering iron is to heat the joint. The flat face of the soldering iron is held directly against the joint assembly so that the heat is transferred effectively to the parts being soldered.
Solder:
Most of the solders used in soldering joining process are made of lead and tin alloys. Some solders also contain small amounts of cadmium and antimony. The amount of % composition of tin and lead determines the physical and chemical properties of joints made with solder. Bar, stick, fill, wire, strip are the different forms solder is available. Solder can be obtained in circular or semi-circular rings or any other desired shape. sometimes the flux can be included with the solder.
Fluxes:
The function of fluxes is to remove the non-metallic oxide film from the metal surface during the heating and soldering operations, so that clean metals may make mutual metallic contact. The flux does not constitute a part of the soldered joint. Commonly used fluxes in soldering joining process are Zinc chloride (Zncl2), ammonium chloride (NH4cl and hydrochloric acid (Hcl).

Brazing

The American Welding Society (AWS) defines brazing as a joining process that takes place above 840°F but below the melting point of the base metals. Most of the brazing operations are done at temperatures ranging from 1100 to 1500°F.
Since, Brazing joining process is done at high temperature, brazing is useful for joining thick metal parts for making relatively stronger joints. Both similar and dissimilar parts can be joined. The success of brazing operation depends upon that a fact that a molten metal of low surface tension will flow easily and evenly over the surface of a properly heated and chemically clean base metal, just as water flows over a clean glass plate.
During brazing the base metal of two pieces to be joined is not melted. An important requirement is that, similar to soldering, the filler metal must be wet the base metal surfaces to which it is applied. some diffusion or alloying of the filler material with the base metal takes place even through the base metal does not reach its solidus temperature.
The surfaces to be joined must be made chemically clean before brazing operation is started. however the fluxes are applied to remove oxides from the surfaces. Borax is the most commonly used flux during brazing process. It will dissolve the oxides of most of the common metals.

Brazing process is similar to soldering but the main difference between brazing and soldering is that brazing requires higher temperature than soldering.

Methods of Brazing:

Based upon the method of heating used in brazing process, different brazing methods have evolved. Two Commonly used methods of brazing are:
  • Torch Brazing:
    Torch brazing is widely used brazing method. Heat is produced, generally by burning a mixture of oxy-acetylene gas, as in the gas welding. A carbonizing flame is suitable for brazing purpose as it produces sufficiently high temperature needed for brazing.
  • Furnace Brazing:
    Furnace brazing is suitable for brazing large number of small or medium parts. Usually brazing filler metal in the granular or powder form or as strips is placed at the joint and then the assembly is placed in the furnace and heated. large number of small parts can be accommodated in a furnace and simultaneously brazed.

Advantages of Soldering and Brazing:

  • Low temperature. Since the base metal does not have to melt, a low-temp heat source can be used. This minimized distortion and creates a smaller heat-affected zone.
  • Joints can be made be permanently or temporarily. Since the base metal is not damaged, parts can be disassembled at a any time by simply supplying heat. The parts then can be reused. The joint made by soldering or brazing process is solid enough to be permanent.
  • Metals of dissimilar can be joined. By using soldering and brazing process dissimilar metals can be easily joined, such as aluminum to brass, copper to steel and cast iron to stainless steel. It is also possible to join nonmetals, i.e. ceramics can be easily brazed to each other or to metals.
  • Speed of joining. Parts can be preassembled and furnace soldered or brazed in large quantities. A lower temperature means less time in heating.
  • Less chance of damaging parts. A heat source can be used that has a maximum temperature below that which may cause damage to the base material.
  • Parts of varying thickness can be joined. Very thin parts or a thick part and a thin part can be easily joined without burning through or overheating them.
  • Easy realignment. Parts can be easily realigned by reheating the joint, re-positioning the parts and allowing the filler metal to solidify.

References:
History of Manufacturing process and usage of materials and composites started dates back to the period 5000-4000 B.C. Recorded history of manufacturing by our ancients is older than actual history, the earliest forms of which were invented by the Sumerians around 3500 B.C. Primitive cave drawings, markings on clay tablets and stone, required some type of a brush and some kind of paint, as in the prehistoric cave paintings in Lascaux, France, estimated to be 15000 B.C period.
The manufacture of things for specific uses began with the production of various household artifacts, which were usually made of either stone, wood or metal. The materials were 1st used in making utensils and ornaments like gold, copper, iron, silver, lead, tin, bronze and brass. The process ways 1st employed involved largely casting and hammering, because they were comparatively straight forward to perform. Over the centuries, these simple processes gradually began to be developed into better and a lot of complex operations, at higher rates of production and increase in levels of product quality.

Anti-lock Brake System (ABS) is an automobile safety system that allows the wheels on a automobiles to continue tractive contact with the road surface as directed by driver steering inputs while braking, preventing the wheels from ceasing rotation and therefore avoiding skidding.

Advantages of Anti-lock Braking System (ABS):

  • ABS guarantees stable braking characteristics on all road surfaces, hence avoids overturning of the vehicle.
  • ABS reduces friction on wheels and road, thus increases efficiency of tires (up to 30%).
  • Vehicle with ABS can be stopped at a lesser distance than a non ABS vehicle.
  • Steering control is effective, i.e., vehicle can be steered smoothly while braking. Thus minimizes the accidents.
  • A driver without experience can drive ABS vehicle effectively, than an experienced driver on the non ABS vehicle.
Vehicle without Anti lock Braking System and with ABS
Image credits: nasva.go.jp

Disadvantages of Anti-lock Braking System (ABS):

  • Initial cost for ABS vehicle is high.
  • Maintenance issues arise as the whole braking system is controlled by engine control unit.
  • On concrete roads, the ABS vehicle stopping distance might be needed more.
Lagrange-d'Alembert principle is generally known as D'Alembert's principle, stated by French physicist and mathematician polymath Jean le Rond d’Alembert.
According to the d'Alembert's principle, the external forces acting on a body and the resultant inertia forces on a body are in equilibrium. This principle is a alternative form of Newton's Second law of motion but this principle suggests that the term "-ma" (product of mass and acceleration) of the body can be considered as a fictitious force, often called the inertia force or d'Alembert's force. Accordingly, the net external force F actually acting on the body and the inertia force Fi together keep the body in a state of fictitious equilibrium.
F + Fi = 0
The d'Alembert's principle gives the solution procedure of a dynamic problem, an appearance like that of a static problem and the above equation becomes equation of dynamic equilibrium.
Rolling Contact Bearings are also known as anti-friction bearing due to its low friction characteristics between ball and inner & outer rings. Rolling Contact Bearings are used for radial load, thrust load and combination of these both loads. Rolling Contact Bearings are often used due to its lower price, less maintenance cost and easy to operate.
Rolling Contact bearings are of two types they are:
  1. Ball bearing
  2. Roller bearing
The rolling contact bearings illustrated below represent a small set of the huge variety of ball and roller bearings.

Thrust Ball Bearing:

Thrust ball bearing
A thrust ball bearing can support an axial load in one direction. These bearings are designed not to accommodate radial loads. The components of these bearings can be easily separated.



Deep Groove Bearing:

Deep groove bearing
In deep groove bearings balls are fitted well into the deep grooves, enabling the bearing to support axial loads in both directions. The bearing illustrated left side has a single row of balls.





Tapered Roller Bearing:

Tapered roller bearing
In tapered roller bearings the inner & outer rings and the rollers are tapered in order to simultaneously support axial and radial loads. In these bearings the ratio of the axial and radial loads supported depends on the angle between the roller and bearing axes. Higher the angle helps to support a larger axial load.




Angular Contact Ball Bearing:

Angular contact ball bearing
Angular contact ball bearings are able to with stand a large thrust load in single direction, in addition to radial loads.






Self-aligning Ball Bearing:

Self-aligning Ball Bearing
In Self-aligning ball bearings there are two sets of balls which one run on a pair of grooves on the inner ring, with a single outer-ring concave surface.







Needle Roller Bearing:

Needle Roller Bearing
Needle roller bearings has long and thin rollers, these bearings are used for applications where radial space is limited.






Spherical Roller Bearing:

Spherical Roller Bearing
In spherical roller bearings there is angular contact between the rollers and raceways, the bearings are able to with stand both axial and radial loads. the double set of rollers in spherical roller bearings permits the bearing to accommodate shaft misalignment. Notice that the rollers of the bearing illustrated left side are not cylindrical and hence the adjective `spherical'.



Cylindrical Roller Bearing:

Cylindrical Roller Bearing
The cylindrical roller bearings are able to withstand large radial loads. The bearing illustrated left side is a single-row bearing. These bearings played a seminal role in the development of the continuous rolling mill.





Wheel Hub Bearing:

Wheel Hub Bearing
Wheel Hub bearings are manufactured in large quantity annually for needs of the automotive industries. These bearings support the radial load due to the weight of the automobile, These bearings also support thrust loads developed when the motion of the automobile is not linear.




Source:
Mechanical Bearings PDF - University of Cambridge
Water hand pumps are manually operated pumps; They are used for bringing water from earth underground to earth surface and is used in every country for a variety of industrial, marine, irrigation and household purposes.
Image shown below is the typical design of Hand Pump.
Typical hand pump design

Hand Pump Parts:

  • Handle
  • Pump rod
  • water outlet
  • Piston
  • Piston valve
  • Foot valve
  • Rising main
  • Suction lift

Principle of Hand Pump:

There are several types of water hand pumps. Most commonly used hand pumps are positive displacement pumps, positive displacement pumps have reciprocating plungers or pistons. In a piston pump, the piston is fitted with the piston  valve (non-return valve) and slides vertically up and down within a cylinder which is fitted with a foot valve (non-return valve). Applying the force on handle of the water pump causes vertical movement of pump rods that are connected to the piston.
When the piston of the pump moves upwards, the piston valve closes and a vacuum is created below the piston valve, Piston valve causes water to be drawn into the cylinder through the foot valve, which opens. Simultaneously, water above the piston, held up by the closed piston valve, is displaced upwards. In a suction hand pump water flows outward through the delivery outlet; in a hand pump with a submerged cylinder it is forced up the rising main.
When the piton moves downwards in hand pump, the foot valve closes to prevent back flow of water and the piston valve opens to allowing the piston to move down through the water in the cylinder.