TECHNICAL ROUND QUESTIONS OF MARUTI SUZUKI INDIA LIMITED !!

1. The purpose of jigs and fixtures are to

a. Increased production rate
b. Increased machining accuracy
c. Facilitate interchangeable manufacturing
d. Enable employ less skilled operators
e. All of the above

Ans:e

2. Tool life of the cutting tool is most affected by

a. Cutting speed
b. Tool geometry
c. Cutting feed and depth
d. Microstructure of material being cut
e. Not using coolant and lubricant
Ans:a

3. A feeler gauge is used to check

a. Radius
b. Screw pitch
c. Surface roughness
d. Unsymmetrical shape
e. Thickness of clearance
Ans:e

4. Metal in machining operation is removed by

a. Tearing chips
b. Distortion of metal
c. Shearing the metal across a zone
d. Cutting the metal across a zone
e. Pushing the metal with tool
Ans:c

5. Ductility of material can be defined as

a. Ability to undergo large permanent deformation in compression
b. Ability to recover its original form
c. Ability to undergo large permanent deformation in tension
d. All of the above
e. None of the above
Ans:a

6. Inconel is an alloy of

a. Nickel, chromium and iron
b. Nickel and copper
c. Nickel and chromium
d. Nickel and zinc
e. Nickel and lead

Ans:a

7. Casting defects caused by the molten metal is

a) Blow holes
b) Swell
c) Scab
d) All of the above
Ans.: d

8. Forming operation which does not involve rotation of work piece is

a) Spinning
b) Thread rolling
c) Ring rolling
d) Upsetting
Ans.: d

9. Greater forging capacity is achieved with

a) Mechanical press
b) Power hammer
c) Hydraulic press
d) None of them
Ans.: c

10. Which of the following welding process uses consumable electrodes

a) TIG
b) MIG
c) Thermit
d) Laser
Ans.: b

11. The crystal structure of alpha iron

a) BCC
b) FCC
c) HCP
d) Cubic
Ans.: a

12. Severe quenching can cause

a) Blow holes
b) Warping
c) Inclusions
d) Non of them
Ans.: b

13. Glass bead peening on components done to

a) Improve creep strength

b) Improve fatigue strength

c) Improve finish

d) Impart further coating

Ans.: b

14. Trajectory of a robot mean :

a) Path traced by the end effectors

b) Kinematics of Robot

c) Robot joints

d) Robot programming
Ans: a

15. Rayleigh’s method of computing the fundamental natural frequency is based on

a)Conservation of energy

b)Conservation of momentum

c)Conservation of masses

d)Laws of statics

Ans: a

Source-https://www.freshersworld.com/

WHY PETAL DISC BRAKES ARE USED INSTEAD OF ROUND DISC BRAKES?

Generally the disc of disc brake is round in shape but few disc brakes have petal shaped disc.What is the reason behind this?We will try to find out the answer of this question in this article.

When we apply brakes the kinetic energy of the wheels is converted to heat energy.As brake pads are in direct contact with the disc, so disc gets heated up.Now, if this heat is not properly dissipated then the disc may get overheated and might change its property.For this purpose, holes are provided in disc brakes.But in extreme conditions we require additional mechanism to remove this heat.For this purpose cuttings are provided in disc in the form of petal,as a result the diameter of disc remains same so effective braking is achieved with enough cooling.

You can notice that not all discs are given petals. Some discs are the usual round ones while only some get petals and there is a good reason for it. The reason petals are given is if the disc is expected to undergo heavy braking forces and has to dissipate a lot of heat a lot quickly or else if the disc is of a smaller size and the area is not enough to handle to heat dissipation rate.

Also petal discs look cooler and they add an extra aesthetic value to the entire thing.

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KNOW WHY BEER BOTTLES ARE GREEN OR BROWN IN COLOUR !!!

You might have imagined why beer is sold in brown or green bottle?Why not in transparent bottle?This article will give you the answer.

In earlier days beer was sold in clear bottles which was transparent. The manufacturers noticed that the liquid in the clear bottles was getting affected by the sunlight and smelled very bad. This is because the UV rays coming from sun reacts easily with the acid in beer when stored in clear bottles. So when light enters beer bottle it breaks down the acid in the hops and this reacts with the already present sulphur, making the beer taste horrible. In order to solve this problem brands started using brown colour for beer bottles as brown stops the UV rays to react with the liquid inside the bottles.

After World War II there was a shortage of brown bottles and hence European manufacturers of beer began to use green bottles. Eventually these green bottles became a symbol of sophistication because most of these Euro beers were of extremely high quality. And so we got to the brown and green variants of a typical beer bottle.

WHY TUBELESS TIRES ARE NOT USED WITH SPOKE WHEELS ??

Now-a-days most of the vehicles are using tubeless tires with alloy wheels but when it comes to spoke wheels we don't see tubeless tires fitted to them. though some top of the line adventure superbikes come with tubeless tyres even on spoke wheels.In this article we will find out the reason why tubeless tires are not generally used with spoke wheels.

The spoke wheels have spoke fitted with the rim.When these spokes are fitted with the rim it leads to formation of small gap between spoke and the rim.If we fit tubeless tires with the spoke wheels the air will escape through these small gaps but in case of tubed tires there is a tube to hold the air so this problem does not arise in spoke wheels.

But there is a solution to this problem which is to seal the part where rim and spoke nipples are fused together. The rim strip is removed, cleaned for any dirt or rust and then the inside of the rim is sealed. One of the common sealants used to seal the wheels are 3M Marine adhesive sealant 5200 or 3M 540 polyurethane adhesive sealant. But this is again not a long term solution.

WHY CRUISER BIKES HAVE HIGH RAKE ANGLE ??

You might have noticed that the angle of inclination of the front shock absorbers is high in case of cruiser whereas in racing bikes it is kept low.Have you ever wondered the reason behind this.

First of all let us understand what this angle of inclination known as.It is known as castor angle or rake angle.The caster angle or castor angle is the angular displacement of the steering axis from the vertical axis of a steered wheel in a car, motorcycle, bicycle or other vehicle, measured in the longitudinal direction. It is the angle between the pivot line (in a car an imaginary line that runs through the centre of the upper ball joint to the centre of the lower ball joint) and vertical. 

Rake angle has a crucial role in a motorcycle’s handling characteristics. Generally speaking (means there are exceptions), the greater the rake angle, the more stable the motorcycle is at higher speeds. It is normally accepted that the responsiveness of a motorcycle’s handling is inversely corresponding to the rake angle values. More precisely, the smaller the rake angle, the more agile the bike is. If you take a look at a chopper and a superbike, you will be able to notice the rake difference between the two.

To better understand this, let us take Honda CBR250 and Bajaj Avenger, as both motorcycles are from  different categories, they have their own characteristics. Let us get into the comparison, Honda CBR250 has a rake angle: 26°, as we all know, Honda CBR250 offers excellent cornering capabilities and it is very flickable, but does not offer a straight-line stability. Coming to Bajaj Avenger, it has a major difference in its rake angle compared to Honda CBR250, this is influenced by the good high-speed stability of the Avenger, but making a U-turn requires a high steering effort.

So,if the rake angle or castor angle is high it leads to better straight line stability but cornering capability is reduced.On the other hand.lower castor angle leads to excellent cornering but reduced straight line stability.

KNOW WHY REAR TIRES ARE THICKER THAN FRONT TIRES IN MOTORCYCLES !!

You might be wondering why motorcycles have thinner front tires than rear.Well this article aims to provide the reason behind it.

First of all let us understand why thick tires are required at rear.In case of motorcycles the maximum weight is on the rear tires so we need thicker tires to withstand that load.Also motorcycles are rear wheel drive vehicle which means the engine drives the rear wheels so thicker tires are required to maintain stability.Also thicker tires increase the grip which also adds to stability to the vehicle.

Now in case of front tires,if we increase the thickness of front tyre then the grip will increase but this increased grip will take much effort of the driver in order to turn the vehicle so the front tires are thinner than rear tires.Also thinner tires cuts a considerable amount of cost.

So these are the reasons why thinner tires are used in front of a motorcycle.If you liked this article share it with friends and let them know.

KNOCKING : REASON AND SOLUTION EXPLAINED !!!

Knocking is a phenomenon of generating unwanted pressure wave which create unpleasant sound and can damage engine wall during combustion in engines. Knocking is largely associated with SI engines. It occurs due to self-ignition of unburned charge into combustion chamber.

When two flame fronts in SI engines collide, they produce an unwanted pressure wave which generates unpleasant sound (knock-knock) and can damage engine wall. Learn more about how Engine knocking works in this article.

Engine Knocking : 

Process:

Knocking is mainly associated with SI engines. It depends on auto ignition quality of fuel. The higher auto ignition temperature causes lower down knocking tendency. To understand whole concept of knocking let’s look out the combustion process.

When the piston reaches at TDC after compression, the spark plug produces spark which ignite the compressed mixture and starts the combustion process. It ignites only those part of mixture witch is in contact with spark plug and generates a main flame front which further ignites the whole mixture. This will generate a high temperature and pressure force inside the cylinder. This burnt part of mixture (combustion products) separate the fresh mixture from spark plug to the other end of the cylinder. As this flame front expands, it compressed the unburned part of the charge. This compression increases the temperature and pressure of unburned part of mixture. If the temperature of this part reaches its auto ignition temperature, it will ignite from other end and a new flame front starts moving towards opposite direction of main flame. When both of these flame fronts collide, it will generate a high pressure wave which produces an unpleasant sound and also damage the cylinder wall.

Factor affecting knocking:

Any factor which tends to decrease auto ignition temperature of charge or tends to ignite the charge except spark plug will affect knocking. Main affecting factor are given below.

Density factor:

The lower dense charge generates low energy and lower rise in temperature thus avoid knocking. If the density of charge decrease, will decreases the knocking tendency. The factors which affect the density of charge are as follows:

Compression Ratio

Increase in compression ratio will increase density of charge thus increase knocking tendency.

Mass of the charge induced:

The mass of charge depends on throttling or supercharging. A reduction in mass of induced charge, reduce the knocking tendency.

Time Factor:

The lower the time available to auto ignition will decrease the knocking tendency. The most affecting time factors are:

Engine Turbulence:

Turbulence reduces the ignition lag or time available for auto ignition. So increase in turbulence will increase the main flame speed and reduce ignition lag, thus reduces knocking tendency.

Spark Plug Location:

To reduce time available for auto ignition, spark plug should locate in order to have minimum flame travel for proper combustion. Generally spark plug located at center to reduce the tendency of knocking.

Engine Size:

As the engine size increase will increase the flame travel thus increases knocking tendency.

Combustion Chamber:

Combustion chamber design play main role in flame travel. The more compact the combustion chamber has minimum flame travel distance thus reduce knocking tendency. Also, the hot spot in combustion chamber should be avoided which can ignite the charge.

Temperature Factor:

Any factor which increases the temperature of inside gases will increase the knocking tendency. These are

Inlet Temperature of Mixture:

More the inlet temperature of mixture, increase tendency of auto ignition thus increase knocking tendency.  

Supercharging:

Supercharging increase both mass and temperature of inside the cylinder thus increases tendency of knocking.

Temperature of Combustion Wall

It will play main role in knocking. The higher the temperature of wall, more chance of auto ignition, thus more chance of knocking.

How to fix knocking:

We have known about knocking phenomenon and factor affecting it. The most methods are used to avoid knock are as follows.

• Spark plug location should select to minimize the flame travel distance.
• By proper cooling of Engine wall.
• Combustion chamber is so design which has less hot spot and higher turbulence.
• Uses higher auto ignition temperature fuels or add additive in gasoline to increase its knocking temperature.
• Higher engine speed will reduce knocking.
• Reduce compression ratio.
• Reduce supercharging to avoid knocking.