Advantages and disadvantages of projection welding

Projection welding is also called as resistance welding produces coalescence of welding material, the heat generated from electric resistance to current through the workpiece hold together with pressure applied to electrodes. Let us have a deep insight into the pros and cons of projection welding in this article. 

Advantages of projection welding :

• It is possible to weld more than one spot at a given time. The number of welds depends on the number of projections that can come under the tip of the electrode. Up to about 6 welds per cycle can be made which substantially reduces the cost of manufacture.
• The welds may be placed closer than possible in spot welding.
• Because of the large-sized electrodes used, their life is much longer than that of the spot welding electrode. The larger contact area makes for very limited deformation of the welding tip.
• They can help in holding the workpieces together in proper alignment during the welding process.
• Proper heat balance can be easily obtained in projection welding by making the projections in thicker plates while welding sheets of different thickness. 
• For welding dissimilar metals, the projections are to be made on the material having higher electrical conductivity to provide proper heat balance.
• The uniformity and appearance of the weld are much better compared to spot welding.

Disadvantages of projection welding :

• Prior operation of embossing is required before welding.
• Electrodes are often to be specially made for a particular operation. This can only be justified when production rates and volumes are large. 

Atomic hydrogen welding

Introduction :

Atomic hydrogen welding is an arc welding process. In this process the arc used in between two tungsten electrodes in a shielding atmosphere of hydrogen. This process was invented by Irving Langmuir in the course of his studies of atomic hydrogen. When Hydrogen is in its atomic state, is a strong reducing gas which prevents oxidation of weld metal and rapid burning of electrodes. Any oxygen present in the surrounding combines with hydrogen forming water which is converted into steam.

Equipment set up :

Set up of this operation consist of hydrogen cylinder, an AC welding machine and the welding torch to accommodate to tungsten electrons, with provision for changing the distance between them. The normal voltage range of the power supply is between 50 to 75 volt with the current varying from 15 to 150 A. This measure is good enough for an electrode size of 1 to 5 mm.

The path of electron travel between the two electrodes is not a straight path as in other arc welding process. Instead, they travel in the form of a fan. This is because the hydrogen atoms formed by the arc causes a downward force because of with electron flow slightly deviates. This fan shape can be changed by altering the distance between the electrodes and the current level. The DC machines could also be used in atomic hydrogen welding, but because of the electron flow is only in one direction, the wear of electron is particularly high and as a result, only AC power supply is used.

When hydrogen atoms recombine near the workpiece surface, they generate a temperature of the order of the 300 0C. Because of this heat, the molten metal becomes highly fluid and therefore, atomic hydrogen welding is used for the flat position only. Filler metal when needed is melted intermittently in the arc fan for fusing with the base metal.

Working principle :

Atomic hydrogen welding the atomic hydrogen welding is an inert gas welding arc welding process done with non-consumable electrodes. The main difference between tungsten inert gas welding and this process is that in atomic hydrogen welding, the arc is obtained between the two tungsten electrodes rather than between the tungsten electrode and the workpiece. This shielding gas used here is hydrogen, which is reactive in nature compared to argon. The hydrogen molecule (H₂), when passing through the electric arc, get this dissociated into two hydrogen atoms (H+). The hydrogen atoms are highly reactive. They form hydrogen molecule and combine with oxygen if present to form water vapour enters release intense heat for the necessary melting of the joint. Because of its type reactivity, the atomic hydrogen is able to break the oxide on the base metal and thus allow the formation of a clean weld. 

Application :

When properly performed, atomic hydrogen welding gives an extremely clean weld with excellent quality. It is generally used for welding of tool Steels containing tungsten, Nickel and Molybdenum as also for hard surfacing and repairing of moulds, dies and tools. Though it can be used for any job, its high cost prohibits its general usage.

Oxy hydrogen welding

Working principle :

In oxy-hydrogen welding, hydrogen combines with oxygen to generate steam and attains a flame temperature of around 2800⁰C. But the weld pool is not protected from the atmosphere when the oxygen for combustion is completely provided by the torch itself. So, Oxygen is an amount slightly less than that required for complete combustion is provided by the torch, whereas atmospheric oxygen accounts for the burning of the remaining hydrogen. This gives rise to a protective preheating flame that surrounds the main flame. But this reduces the flame temperature to some extent. Because of the lower flame temperature, oxy-hydrogen welding is a generally slow process. It is normally used to weld thin sheets of steels and alloys with low melting temperatures.

Key features :

• Operation is convenient & safe

Oxy hydrogen generator produces oxygen and hydrogen gas that you required and also no gas cylinder is required. There is no risk of explosion.

• Environmental friendly 

In this process, fuel comes from water and there is water vapour after finishing this process so this process is environmentally friendly.

• Welding features 

Welding work is fast, precision, smooth and beautiful welding spot. The oxyhydrogen flame is concentrated up to 2800 ⁰C so it can heat the welding spot to melting point very quickly.

• Energy-saving and low cost 

This process is done with very low electricity and pure water. The cost of electricity and water is reduced by more than 40% compared with LPG and other welding processes.

Tungsten inert gas welding

Tungsten inert gas welding is also known as gas tungsten arc welding.

In this process, an inert gas shielded arc welding process using a non-consumable electrode. The electrode may also contain 1 to 2% thoria mix along with the core tungsten or tungsten with 0.15 to 0.40% zirconia. The pure tungsten electrodes are less expensive but also it will carry less current. The thoriated tungsten electrodes carry high current and more desirable because they can strike and maintain a stable at with relative ease. The zirconia added tungsten electrode better than pure tungsten but inferior to thoriated tungsten electrodes.

The process set up :

Tungsten inert gas welding setup is shown in figure it consists of a welding torch at centre electronic inert gas is supplied to the welding zone through the Anil apart surrounding the tungsten electrode to effectively displays the atmosphere Around The World Patel the smaller world tours may not be provided with Anni cooling device for the electrodes but larger ones are provided with circulating cooling water 30 welding process can be used for joining a number of materials through the more aluminium magnesium and stainless steel.

Components used :

• Power Supply (A.C or D.C)
• Filler Rod
• Non-consumable Tungsten electrode
• Welding Head
• Inert Gas Supply

Working principle :

TIG welding process is relatively difficult to perform out of another welding process because it normally requires two hands for the process to be performed while other processes require that the welder manually feed a filler metal into the weld area with one hand.

In this process, first of all, strike the welding arc that can be produced by torch. A high-frequency generator provides an electric spark. This spark is a conductive path for the welding current through the shielding gas and it allows the arc to be initiated while the electrode and the workpiece are separated. The inert gas forms a gas shielding around the weld. It protects the weld from the external atmosphere. 

Once the arc is struck, the welder moves the torch in a small circle to create a welding pool, the size of that depends on the size of the electrode and the amount of current then torch moves back and filler metal is added manually to the front end of the weld pool as it needed.
The arc current is often gradually reduced to allow the weld crater to solidify and prevent the formation of cracks at the end of the weld. Thus, this process can be done.

Advantages of TIG welding :

• It produces high quality and clean welds.
• No slag is produced so welds are not weakened.
• The weld is automatically protected by the inert gas during the welding process so welds are corrosion resistance, more ductile, and stronger.
• This process can apply for any position of welding like wise horizontal, vertical or flat.
• It can be performed by both automatic and manual technique.
• It easily applied to thin material and used for a wide range of metal thickness.
• There is less distortion of work piece because the small heat affected zone.
• Only the necessary amount of filler metal is added to the welding puddle so there is no spatter or sparks are produced.
• Use one shielding gas mainly Argon for all applications.
• In this process finishing process required little or less. Sometimes grinding or preparation before it can be painted.
• It is the preferred choice in most of the intricate works, where shape of each and every weld joint counts.

Main most common limitations of TIG welding is low deposition rate of the filler and metal per pass so that time increased to completed the welds that's why it is mostly used for thinner metal. More than that it has certain disadvantages we can check it below :

Disadvantages of TIG welding :

• As we seen it is slow process.
• More complicated process so that highly skilled labour is required.
• Less economical than consumable electrode for sections thicker than 3/8 inch.
• Tungsten inclusion.
• Welder is exposed to the huge intensities of light.
• This process is also more expensive.
• Sensitive to drafts.

Tungsten Inert Gas Welding offers several advantages that account for its popularity and its use in agriculture and many other industries. 

Applications of Tungsten Inert Gas Welding :

• Stainless steel
• Alloy steel
• Aluminium
• Titanium
• Copper
• Magnesium
• Nickel alloys

Broaching machine

Broaching process is the simplest of all machine tools that can be performed on a broaching machine. It can be consist of a work welding fixture, broaching tools, a drive mechanism and suitable supporting frame. Although the component parts are few, several variations are possible. 

There are two principal types of machine :

• Horizontal 
• Vertical 

In addition to these standard types, there are special and continuously operating machines. Both horizontal and vertical types have one or more rams depending on production recruitment. Dual ram models are arranged so that when one ram is on the cutting stroke the other is on the return stroke and the return stroke is performed quickly to gain time, which is used to and load the machine. 

Broaching machines usually pull or push the approach through, or past a work piece that is held in a fixture. On some machines, however, the work piece is moved past that is fixed position. Most broaching machines operated to secure a smooth, uniform cutting action.


Horizontal broaching machine :

Most of all broaching machines at the pull type. They may be used for either internal or external broaching. The horizontal broaching machine consists of a bed or a little more than twice the length of broaching stroke, a broach pilot and the drive mechanism of pulling the brooch. 
It is used in many application especially for broaching keyways, splines, slots, round holes and other internal shapes or contours. They have the disadvantages of taking more floor space than vertical machines. 

Vertical broaching machine :

The vertical type may be obtained in either push or pull type. The push-type is more popular. It can be employed in multiple operations, since they are convenient to pass work from one machine to another, and they are more likely to be found doing surface operations. Of the three models available pull-up, pull-down and push down, the pull-up type is most popular. 

Vertical machines require an operator platform or a pit and are economical of floor space than the horizontal type.


Surface broaching machine :

Surface broaching machines have their broaching tools attached to the ram or ram forced in a straight path along with guide ways past the work piece. On some machines, the ram moves horizontally on other vertically. When two rams are used, the machine is called duplex broach. 


Continuous broaching machines : 

For mass production of smart small parts, the highly productive continuous broaching method is used on rotary or horizontal continuous-broaching machines. 

In this machine the work piece is loaded on the table which rotate continuously. During the operation the broach is stationary. 

In the horizontal continuous broaching machine the work piece travel as they are carried by an endless chain. The work piece are loaded into work holding fixture that is mounted on the continuous moving chain. During the operation the broach is stationery as before. Such machines are used for broaching small parts.

Types of belt drive

A belt drive is one of the most common and effective means of transmission of motion from one shaft to another shaft. There are different belt drive used for different applications. Now we can see the different types of belt drive :

Types of belt drive :

According to the power transmitted :

1. Light belt drive 
2. Medium belt drive 
3. Large belt drive 

According to the arrangement of the belt :

1. Open belt drive
2. Crossbelt drive
3. Quarter twist drive
4. Right angle drive
5. Stepped pulley drive
6. Fast and loose pulley drive 
7. Compound drive 

VTVT vs CRDI

VTVT and CRDI are the fancy names given to engines from different manufacturers. 

Let us have a deep insight into the difference between VTVT and CRDI. 

VTVT is standing for variable valve timing valve train has ability to independent control of the intake and exhaust valves in an automobile engine on different engine load criteria.

CRDi stands for common rail direct injection is a fuel injection mechanism to supply the requisite amount of fuel at constant pressure and also to maintain a certain amount of pressurized reserve fuel during starting of the engine.

Mostly VTVT technology used for petrol engine while CRDi technology working for a diesel engine.

Application of belt drive

There are different variations of industrial machining application of belt drive that employ a wide range of different types of synchronous timing belt drive systems. 

Application of belt drive :

• Automobile timing belt 
• Treadmills
• Sewing machine
• Drilling machine with speed cone pulleys
• An open belt drive in a jig-saw machine
• Lathe machine with time belt
• A planner machine with guide pulleys 
• A flat belt in a circular saw machine  

Belt drive vs Chain drive

Chain and belt drive are both allow locomotive and a transfer of power within a particular piece of machinery. Both are used in many vehicles and other mechanical applications like garage doors. Now we will discuss the difference between both two drive and what is more effective?

Difference between belt drive and chain drive :

• A chain drive is driven by a chain loop while a belt drive is driven by a belt.
• A chain drive is made of a metal which makes them more durable and stronger as compared to belt while belt drive is made of synthetic material.
• A chain can transmit more power and last longer, but typically a belt is quieter.
• A belt drive gives you lower power transmission efficiency than a chain drive because it will allow higher levels of misalignment between sprockets. Belts are a little more elastic, so they can run tighter to eliminate play or backslash.
• Replacement of belt is very easy and cheap so it needs little maintenance and has only three moving parts called belt and two pulleys whereas the chain literally consists of hundreds of pieces, side plates, rivets, bushes and rollers.
• A chain drive is comparatively efficient than belts.
• If you are using a chain drive in a coastal area with lots of salt in the air, take care of that chain drive. Clean it and keep it lubricated or you will get corrosion which always takes strength away over time which will make you upset.

Conclusion :

The main advantage of a belt is expansion due to a temperature which is minimal and is capable of slipping and also can be used as a safety device. The sounds generated by the belt is minimal so tape recorders use belts. It can absorb vibrations and it is less noisy. It has to be bulkier than a chain to have the same strength so chains are used in some places and belts in other places depending on the desired requirement. There are many different varieties of belts than chains to suit their needs. You can use depending on your requirement.

Belt drive vs Gear drive

A belt drive is a system of connecting to wheels by a belt whereas gear drive is two gear is connected with each other as corresponding to both teeth are connect interconnected. Now we will discuss the difference between both two drive and what is more effective?

Difference between belt drive and gear drive :

• Belt drive has lesser life as compared to that of the gear drive.
• Belt drive requires more maintenance as compared to gear drive but maintenance cost if less in belt drive.  
• Belt drive system does not require lubrication while in case of gear drive required lubrication on a regular interval.
• Safety is less in belt drive as compared to the gear drive.
• A belt drive is quieter in operation than that of the gear drive.
• A belt drive is less efficient than gear drive due to more frictional loss. 
• In a belt-drive, there exists some slip between the two pulleys while transmitting power However, in gears the slip does not occur as it is a positive drive. 
• Gear drive is having higher transmission efficiency than belt drive.
• Higher speeds efficiency of belt drive is very low as compared with gear drive.

Conclusion :

• If you want a quiet vibration operation then you choose belt drives and if an operation requires ruggedness and efficiency then go for gear drives. 
• For shorter distances, gear drives are best and longer distances belt drives.
• To gain higher torque and power gear drive is used.

Broaching process

Introduction :

Broaching is one of the most precise and productive processes in metalworking areas. In this process removal of a layer of material of desired width and depth usually in one stroke by a slender rod or bar type cutter having a series of cutting edge. It can be performed on a broaching machine.

The broaching term may have derived from ancient Roman word braces, which meant an object having projecting teeth. The operation itself dates only to the 1850s when broaching tools, then called "drifts" were hammered in blacksmith shops through the work or pushed through with an arbour process.

Basic principles of broaching :

Broaching is a process of machining in which removal of a layer of material of desired width and depth usually in one stroke by using a slender rod or bar type cutter. This rod or cutter having a series of cutting edges with gradually increased protrusion. Broaching and shaping are similar processes while in shaping, attaining full depth requires a number of strokes to remove the material in thin layers step by step by gradually in feeding the single point tool. Whereas, the broaching process can remove the whole material in one stroke by using a bar type cutter is called broach. 

By using the broaching process various forms of holes and various size of the section, internal and external through straight or helical slots or grooves or external surfaces of different shapes can be made. Teeth of external and internal splines and small spur gears are also been made by broaching.

Construction And Operation of Broaching :

Construction of any cutting tool is characterized mainly by :

• Configuration
• Material 
• Cutting edge geometry
• Configuration of the broaching tool

Pull and push-type broaches both are made in the form of slender rods or bars of the varying section having along with one or more rows of cutting teeth with increasing height. But push-type broaches are subjected to compressive load and therefore they are made shorter in length to avoid buckling.

The essential elements of the broach are following below :

• Pull end for engaging the broach in the machine.
• The neck of shorter diameter and length.
• The front pilot for initial locating the broach in the hole.
• Roughing and finishing teeth for metal removal.
• Finishing and burnishing teeth.
• Rear pilot and follower rest or retriever.

Broaches are designed mostly pull-type to facilitate alignment and avoid buckling. 

The length of the broach is mainly depended on :

• Type of the broach ( Pull or Push type ).
• Number of cutting edges.  
• Pitch depending upon the work material. 
• The maximum thickness of the material layer to be removed.
• Nature and extent of finish required.

Broaches are generally made from solid rod or bar. The broaches of large section and complex shape are made by separate sections or inserting separate teeth.

The material of broach :

In broaching process for cutting broaches are used. That is made of materials having the usual cutting tool material with high hardness, strength, toughness and good heat and wear resistance properties.

For ease of manufacture and resharpening the complex shape and cutting edges, broaches are mostly made of HSS (high-speed steel). Nowadays cemented carbide segments or replaceable inserts are used especially for stronger and harder work materials like steels and cast iron. TiN-coated carbides provide much longer tool life in broaching.

Broaching operation :

Broaching operation can done by a series of following sequential steps :

• Selection of broach and broaching machine
• Mounting and clamping the broach in the broaching machine
• Fixing workpiece in the machine
• Planning tool - work motions
• Selection of the levels of the process parameters and their setting
• Conducting machining by the broach.

Methods of broaching process :

• Pull broaching :

In this type of broaching the work is held stationary and the brooch is pulled through the work. broaches are usually long and are held in a special head. Pull broaching is used mostly for internal broaching but it can do some surface broaching.

• Push broaching :

In this type of broaching the work is held stationary and the broach is pushed through the work hand and hydraulic arbor press are popular for push broaching, this method is used mostly for sizing holes and cutting key ways. 

• Surface broaching :

In this type of broaching either the work or the broaching tool moves across the other. This method has rapidly become an important for surface finishing. Many irregular or intricate shapes can be broached by surface broaching, but the tools must be specially designed for each job.

• Continuous broaching : 

In this type of broaching the work is moved continuously and the broach is hell stationery. The path of moment maybe the straight horizontal or circular. This method is very suitable for broaching number of similar works at a time.

Different Types of broaches and their applications :

Broaching is widely used machining process, wherever feasible, for high productivity as well as product quality. There are different types of broaches have been developed and are used for wide range of applications.

Broaches can be broadly classified in several aspects such as 

Type of operation :

• Internal broaching 
• External broaching 

Method of operation :

• Push type 
• Pull type

Type of construction :

• Solid
• Built-up
• Inserted tooth 
• Progressive cut 
• Rotor cut 
• Double jump or overlapping tooth

Function :

• Surface
• Keyways
• Round hole 
• Splint
• Spiral 
• Burnishing 

Broaching of inside surfaces is called internal broaching or hole broaching and of outside surfaces, external or surface broaching. Internal broaching tools are designed to enlarge and cut various contours in holes already made by casting, forging, rolling, drilling, punching etc. It offers a combination of a high degree of accuracy and excellent surface finish, combined with high output rate and low downtime.

A push Broach is one that is designed to be pushed through the workpiece by special press or a push broaching matching. Because of tendency to band under compressive loads the push broach must be short and stocky, which means fever teeth are in broach and less material can be removed for each pass of the tools.

In a pull broach the tool is entirely in tension and long slender broaches are possible having a large number of teeth, consequently more stock can be removed for each pass.

When a brooch is made is one piece, it is called solid broach. Internal broaches are usually of the solid type. Broaches are sometimes build up of several sections and sometime made up of a series of teeth inserted in a block of steel. 

Surface broaches are usually of the build up or inserted tooth type. 

Progressive cut broaches have teeth a part of which are of the same height and have different width. In progressive cut broaching, metal is removed in thick layers by each tooth from only part of work-surface. The last teeth of a progressive cut broach remove a thin layer over the entire profile of work surfaces in ordinary cut broaching. 

Rotor cut broaches are used for removing large amount of materials in holes where forging or castings where a primary cutting operation is not desired. Teeth are staggered around the periphery at different sections so as to shear the work and allow cheap clearance. This would be an ideal tool to use for making a square hole from around cast one. 

A burnishing process makes a glazed or finished surface in steel, cast iron or nonferrous hole. Burnishing teeth are round and do not cut but compress and rub the surface metal. The amount of stock left for burnishing should not exceed 0.025 mm.

Advantages of broaching :

• Very high production rate. Mainly higher than milling, planing, boring etc.
• High dimensional, high accuracy and high class of surface finish of the product is possible.
• Roughing and finishing in single stroke of the same cutter.
• Needs only one motion of cutting, so design, construction, operation and control are simpler.
• Extremely suitable and economic for mass production.
• Expertise not needed.
• Remarkable finished face.
• Short cycle time with high accuracy.
• Little skill is required to perform a broaching operation. In most cases the operator merely loads and unloads the work piece.

Limitations of broaching : 

• Only through holes and surfaces can be machined.
• Usable only for light cuts.
• Cutting speed cannot be high.
• Defects or damages in the broach severely affect product quality.
• Design, manufacture and restoration of the broaches are difficult and expensive.
• Economic only when the production volume is large.
• Very large work piece can't be broached.

Advantages and disadvantages of broaching

Broaching is one of the most precise and productive processes in metalworking areas. In this process removal of a layer of material of desired width and depth usually in one stroke by a slender rod or bar type cutter having a series of cutting edge. It can be performed on a broaching machine. Let us have a deep insight into the pros and cons of the broaching process. 

Advantages of broaching :

• Very high production rate higher than milling, planing, boring etc.
• High dimensional and form accuracy and surface finish of the product.
• Roughing and finishing in a single stroke of the same cutter.
• Needs only one motion of cutting, so design, construction, operation and control are simpler.
• Extremely suitable and economical for mass production.
• Expertise not needed.
• Remarkable finished face.
• Short cycle time with high accuracy.
• Little skill is required to perform a broaching operation.
• Broaching can be used for either internal or external surface finishing.
• A tolerance of +-0.0075 mm and a surface finish of about 0.8 microns can be obtained in this process.
• Cutting fluid may be readily applied where it is most effective because a broach tends to draw the fluid into the cut.

Disadvantages of broaching : 

• Only through holes and surfaces can be machined.
• Usable only for light cuts.
• Cutting speed cannot be high.
• Defects or damages in the broach severely affect product quality.
• Design, manufacture and restoration of the broaches are difficult and expensive.
• Separate broach has to be procured and used whenever size, shape and geometry of the job changes.
• Economic only when the production volume is large.
• A very large workpiece can not be broached.
• High tool cost.
• Broaching can not be used for the removal of a large amount of stock.
• Parts to be broached must be capable of being rigidity supported and must be able to withstand the forces that set up during cutting.

What is belt drive

Introduction :

To transmit power from one shaft to another pulley are mounted on the two shafts. The pulleys are then connected by an endless belt or rope passing over the pulleys. The connecting belt or rope is kept in tension so that the motion of one pulley is transferred to the other without slip. The speed of the driven shaft can be varied by wearing the diameter of the two pulleys. 

What is belt drive?

Belt the drive is a mechanism in which power is transmitted by the movement of a continuous flexible belt. 

A belt may be a rectangular section is known as a flat belt or of the trapezoidal section known as V-belt. In case of a flat belt, the rim of the pulley is slightly crowned which helps to keep the belt running centrally on the pulley rim. The groove on the rim of the pulley of a V-belt is made deeper to take advantage of the wedge action. The belt does not touch the bottom of a groove. Owing to wedging action V-belt needs a little adjustment and transmit more power without sleep as compared to flat belt also multiple V-belt a system using more than one belt in the two pulleys can be used to increase the power transmitting capacity generally these are more suitable for shorter centre distance. Thus, belt drive works on the law of belting. 

Open belt drive :

An open belt drive used when the driven pulley is desired to be rotated in the same direction as the driving pulley.  

Generally, the centre distance for an open belt drive is 14 to 16 metre. If the centre distance is too large, the belt whips vibrate in a direction perpendicular to the direction of motion. For very short at the centre distance, the belt sleep increasing. Both these phenomena limit the use of belts for power transmission.

Crossbelt drive :

A the crossed-belt drive is adopted when the driven pulley is to be rotated in the opposite direction to that of the driving pulley.

A cross belt drive can transmit more power than an open belt drive as the angle of wrap is more. However, the belt has to be a band in two different planes and it we are out more. 

Advantages of belt drive :

• A belt drive is simple and economical.
• Wide range of speeds is available.
• In belt drive don't need parallel shaft.
• Noise and vibration are damped out.
• Machinery life is increased because load fluctuations are shock-absorbed.
• Less maintenance cost because no lubrication are required.
• Belts permit flexibility ranging from high horsepower drives to slow speed and high speed drives so it is highly efficient in use.
• A flat belt is best for very high-speed drives.
• This drive is very economical even when the distance between the shaft is very large.
• Belts will slip under overload conditions this leads the biggest advantages that preventing mechanical damage to shafts, keys, and other machine parts.
• All the belt drives do not need the pulleys to be maintained at the same height.

Disadvantages of belt drive :

• Operating temperature is restricted up to 80 to 85⁰C.
• Heat buildup occurs.
• Belts can't be used where exact timing or speed is required because of slippage.
• Because of slipping and stretching the angular velocity ratio is not necessarily equal or constant to pulley diameter ratio.
• In belt, drive belts are damaged easily by abrasives or heat or some chemicals.
• Some adjustment of centre distance or use of an idler pulley is necessary for wearing and stretching of belt drive compensation.
• Speed is limited to usually 35 meters per second.
• Power transmission is limited to 370 kilowatts.

Applications of adsorption

Applications of adsorption :

• Activated charcoal is used in gas masks in which all undesirable or toxic gases are observed selectively by charcoal, while purified air passes through its pores. 
• Activated charcoal is used for removing colouring matter of sugar solution and the decolouration of vinegar. 
• Silica and Alumina gels are used as an adsorbent for removing moisture and for controlling humidities of room. Silica Gel has been employed for drying air, used in blast surfaces.
• Charcoal adsorption filters are used for removing organic matter from drinking water.
• Selective adsorption by alumina, magnesia has been used for separating different pigments by adsorption chromatography. 
• During arsenic poisoning, colloidal fabric hydroxide is administered. The letter absorbs the arsenic poison and retails it can thus be removed from the body by vomiting. 
• Fuller's earth is used in large quantities for refining petroleum and vegetable oil due to its good adsorption capacity for unwanted materials. 
• The phenomenon of adsorption is useful in heterogeneous catalysis Example: contact process, Haber's process, hydro generation of oils based on the adsorption process. 
• Adsorption the process is used in the production of a vacuum by using activated charcoal in dewar's flask.
• Lake test for Al⁺ Lake test for Al⁺³ is based upon adsorption of litmus colour by Al(OH)₃ precipitate. 
• Mordants used in Dying cloth, adsorb the dye particles, which otherwise, do not speak to the clothes.

Advantages of gear drive

Gear drive is used to transmitting mechanical power from one place to another, often used to convey power to wheels of the bicycle and motorcycles. It is also used in a wide variety of machine apart from the vehicle. Let us have a deep insight into the advantages of gear drive in this article. 

Advantages of gear drive :

• It is very compact and needs less space.
• Most convenient for very small centre distances.
• The velocity ratio will remain constant throughout and any velocity ratio up to 60:1 can be obtained.
• It has very high efficiency which is very useful in transmitting motion.
• It will be possible to transmit the power if the axes of the shafts are not only parallel, but even when the axis of the shaft is nonparallel, intersecting, non-intersecting and coplanar or non-coplanar by using different types of gears.
• They can be used conveniently for transmission of low, medium and high power.
• It is a reliable service that is a very good advantage.
• Gears are employed for a wide range of applications like in watches, precision measuring instruments, machine tools, gearboxes fitted in automobiles, aero engines, etc.
• Gears may be cast integral with the shafts if required. 
• In a wide range of metallic and non-metallic materials, gears can be cast.
• It provides a large range of speed and torque for same input power. 
• It is compact and needs less space.