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Monday, December 9, 2013

Solidworks Models For Practise Part 1

Solidworks Exercise 1
Solidworks Models For Practise Part 2

Solidworks Exercise 201-a shaft support - solidworks drawing
Solidworks Exercise 301-rod support - solidworks edrawings

Solidworks Exercise 401-shaft support - solidworks exercises
Solidworks Exercise 5
01-vertical shaft support - solidworks drafting
Rod / Shaft Support:

Shafts, too, are a basic, important and very common machine element. A shaft is usually designed to perform a specific task in a specific machine. In general, a rotating member used for the transmission of power is called shaft. A shaft known variously as a DRIVESHAFT, TAILSHAFT or CARDAN SHAFT (and sometimes as a JACK SHAFT). It is used to transmit power and torque from the rear of an automotive gearbox (on the left) to the input shaft of the differential, which is known as the PINION SHAFT (on the right).

E.g. Gears must be mounted on some sort of shaft, and a gate valve or globe valve is opened and closed by a hand-wheel turning another type of shaft often referred to as a spindle.

Different types of shafts are:

Stub shaft – A shaft which is integral with an engine, motor or prime mover and is of suitable size, shape and projection to allow its easy connection to other shafts.

Ex.: It allows a power-transmission device such as a belt pulley to be fitted to drive an external machine.

Line shaft (or power transmission shaft) – A shaft connected to a prime mover which transmits power to a number of machines – now mostly superseded by machines having individual motors.

Ex.:  The overhead LINE SHAFT ran continuously and individual machines could be stopped only by moving the flat drive belts from the driving pulley onto a free-running pulley. Note the largely timber construction of the building, allowing significant flexing of the structures under load.

Jack shaft – A short shaft used to connect a prime mover to a machine or another shaft. May also be a short shaft placed as an intermediate shaft between a prime mover and driven machine.
Ex.: Speed Reduction similar to gear drives.

Flexible shaft – Permits the transmission of power between two shafts (e.g. motor shaft and machine shaft) whose rotational axes are at an angle or where the angle between the shafts may change.
Ex.: Japanese style backpack mower with flexible shaft between the red power pack and the usual hand-held mower assembly. In general, flexible shafts are not used to transmit high powers or high speed.

Most shafts are made from steel, either low- or medium-carbon. However, high quality alloy steel, usually heat treated, may be chosen for critical applications. Small, light-duty shafts, e.g. in household appliances, may be injection moulded in a plastic material such as nylon or derlin. Other metals, e.g. brass, stainless steel or aluminium, may be used where corrosion is a problem or lightness is required.

The suspension of copper tubing presents a challenging problem in corrosion. If local corrosion conditions are severe due to acid fumes, extreme humidity, etc., copper plated steel is not satisfactory and special materials must be used. The threat of galvanic corrosion is mitigated. No electrical continuity between the pipe and support beam.

These flanged support blocks are specially developed for securing the shaft at right angles to the mounting surface. This Flanged supports made of spheroidal graphite cast iron with flanged liner sets.
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Mechanical Engineer Job Interview Questions Part 2


1. What is the importance of the Thermodynamics in the field of Mechanical Engineering?
All the mechanical engineering systems are studied with the help of thermodynamics. Hence it is very important for the mechanical engineers.

2. How many Laws of Thermodynamics are there?
There are three laws of the thermodynamics.

First Law: Energy can be neither created nor destroyed. It can only change forms.In any process in an isolated system, the total energy remains the same.

Second Law: When two isolated systems in separate but nearby regions of space, each in thermodynamic equilibrium in itself, but not in equilibrium with each other at first, are at some time allowed to interact, breaking the isolation that separates the two systems, and they exchange matter or energy, they will eventually reach a mutual thermodynamic equilibrium. The sum of the entropies of the initial, isolated systems is less than or equal to the entropy of the final exchanging systems. In the process of reaching a new thermodynamic equilibrium, entropy has increased, or at least has not decreased.

Third Law: As temperature approaches absolute zero, the entropy of a system approaches a minimum.

3. State Laws of conservation of energy?
According to the laws of conservation of energy, “energy can neither be created nor be destroyed. It can only be transformed from one form to another.”

4. Is the boiler a closed system?
Yes definitely the boiler is a closed system.

5. What is Carnot engine?
It was being designed by Carnot and let me tell you that Carnot engine is an imaginary engine which follows the Carnot cycle and provides 100% efficiency.

6. Which formula forms a link between the Thermodynamics and Electro chemistry?
Gibbs Helmholtz formula is the formula which forms the link between the thermodynamics and electromagnetism. ∆Hs/R = [∂ lnp /∂ (1/T)]x

where: x – mole fraction of CO2 in the liquid phase
p – CO2 partial pressure (kPa)
T – temperature (K)
R – universal gas constant
α – mole ratio in the liquid phase (mole CO2 per mole of amine)

7. Which is the hardest compound known?

8. What is Hess Law?
According to the Hess law the energy transfer is simply independent of the path being followed. If the reactant and the product of the whole process are the same then same amount of energy will be dissipated or absorbed.

9. Which has more efficiency: Diesel engine or Petrol engines?
Off course Diesel engine has the better efficiency out of two.

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Solidworks Models For Practise Part 2

Mechanical seals are leakage control devices, which are found on rotating equipment such as pumps and mixers to prevent the leakage of liquids and gases from escaping into the environment. A mechanical face seal is an important component of variety of pumps used in chemical, petrochemical and process industry.

The seal is designed to fit around the shaft or some part connecting to the shaft in a way such that the leakage  between the two regions is acceptably small under all circumstances of operation.

Wherever the rotating shafts are used, shaft seals find their place with them. Generally rotating shafts either run into fluids where  the fluid is sealed by the shaft seal or are supported by bearings, which are in turn sealed by a shaft seal. Thus almost all rotating equipment require a shaft seal.

The various types of mechanical equipment that utilize shaft seals are as follows:
  • Aerospace industries where motors and engines in rockets and turbo jets.
  • Water pumps used in irrigation, pumping of fertilizers and insecticides.
  • Swimming pool pumps and garbage disposal pumps, dishwashers and washing machines use small sealed pumps.
  • Water turbines, steam turbines, feed pumps, and nuclear reactor cooling pumps.
  • The petroleum, chemical, textile and drug industries all use pumps extensively in their respective processes. 
  • All automotive engines, compressors, air conditioners.
  • Ship propeller shafts as well as its auxiliary equipment in ship yards.
Solidworks Model 2
01-hexagonal block clamping elements - solidworks model online
The sliding clamp is manually placed in the T-slot and screwed against the die clamping edge. Once the high-pressure spindle has been adjusted to suit the height of the clamping edge, the clamping force is built up by turning the hexagon nut in a clockwise direction. The clamping force achieved depends on the tightening torque selected with the torque wrench. If the parts are not rigid, tighten the high-pressure spindle using the hexagon nut until there is no play.
  • For clamping and locking dies on press beds and rams
  • On beds of machine tools
  • When the available space is limited
Solidworks Model 3
01-stage - solidworks model for practise
SolidWorks is a 3D solid modelling package which allows users to develop full solid models in a simulated environment for both design and analysis. Designing in a modelling package such as SolidWorks is beneficial because it saves time, effort, and money that would otherwise be spent prototyping the design. SolidWorks software provides users with an intuitive 3D experience that maximizes the productivity of your design and engineering resources to create better products faster, and more cost-effectively.

Today, most manufacturers of automobiles, arm and construction equipment, recreational vehicles and other gasket-using equipment apply three-dimensional (3D) computer-aided design (CAD) software to create product models.  The technology allows designers to produce engine and ultimately whole vehicle designs solely on computers. By modelling in three dimensions, the designers can do electronically all the spatial fitting of a components with respect to clearances and tolerances, avoiding a lot of rework on actual hardware.

Solidworks Model 4

01-tray - solidworks model share
CAD software supplies the tools for both design and manufacturing to create and explore various shapes, mechanisms, and structures.  The software enables all the geometries to effectively communicate together.  In turn, you are able to view and troubleshoot a concept without prototyping, cutting, forming, etc. Solid models are characterized by the definition of 3D volumes, both interior and exterior. In addition to volume and mass property data, Solid models usually provide cross section and interference detection.

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Thursday, December 5, 2013

Mechanical Engineer Job Interview Questions Part.1


What is the function of EGR valve?

EGR means Exhaust Gas Recirculation. The main function of EGR is to control NOx emission from the engine. At elevated temperature (during long run & full condition)if due to some reasons engine gets heated up beyond certain level… it produces NOx emission. In order to avoid this pollution , we have to control the temperature rise inside the cylinder. This can be achieved by mixing some amount of exhaust gas with intake air. By doing this the temperature inside the combustion chamber is reduced. And NOx is controlled.

What is the difference between Critical speed & Whirling speed?

In Solid mechanics, in the field of rotor dynamics, the critical speed is the theoretical angular velocity which excites the natural frequency of a rotating object, such as a shaft, propeller or gear.

As the speed of rotation approaches the objects natural frequency, the object begins to resonate which dramatically increases system vibration. The resulting resonance occurs regardless of orientation.
Whirling Speed is due to the unbalanced forces acting on a rotating shaft.

What is the significance of Torque(in N-m) given in the engine specification ?

It give the moment about any point or simple rotation.

What is the abbreviation of Welding rod 7018?
70= tensile strength 70000psi
1=  welding position
8= current flux

What are the uses of Graphite electrode in various field?
Graphite electrode is used in EDM.. and in Battery cells..
It is also used in electric arc furnaces to melt the steel.

Difference between TIG & MIG welding?

Tungsten inert gas welding-non consumable electrode.
MIG-Metal inert gas welding-uses consumable electrode

Specific speed of turbine?

The specific speed is defined as the the speed of the geometric turbine which can produce unit power at unit head

Material of Aircraft turbine blade?

Ni, Cr, Al, Traces of C

Do you know epicyclic gear box? What are the practical application of epicyclic gear box?
Epicyclic gear box consists of sun gear planetary gears and an annular called ring gear. Different speed ratios are obtained by locking any one gear. If you lock any two gear , direct gear will be obtained. Mostly used in overdrives. Wrist watch is a practical application of epicyclic gear box

What do you mean by super critical above 500MW in Thermal power plant?

In super critical boiler means all the steam to converted in to superheated steam at outlet of boiler no need to sent to super heater once again.

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