Seven Quality Tools - New

Seven new quality tools also called as seven management and planning (MP) tools are the tools developed by Union of Japanese Scientists and Engineers JUSE in 1976. Mostly they are based no operation research work done after second world war. These tools are meant to promote innovation, information communication and successful planning of major projects.

The seven new quality tools are

1. Affinity diagram:

It is also know as KJ method which was named after a Japanese anthropologist Jiro Kawakita. It is a kind of brain storming tool that organizes large amount of disorganized data and information into groupings based on their natural relationships. This diagram is useful where, there are many facts or ideas in apparent chaos and issues seem to be too large and complex.

2. Interrelation Diagram (ID):

Similar to earlier cause and effect diagram this tool helps to analyze the natural links between different aspects of a complex situation.

3. Tree Diagram:

It is a systematic approach to breakdown broad categories into finer and finer details. This helps the thinking process to progress step by step from generalities to specifics.

4. Matrix Diagram:

This diagram shows relationship between groupd  of information about strength and role played by different indivisuals and measurements.

5. Matrix data analysis:

This is a complex mathematical technique for analysis of matrices. This tool is often replaced by a similar but more rigorous decision making tool known as prioritization matrix.

6. Arrow Diagram:

This diagram shows the tasks to be performed in their required order. It also gives best schedule for the entire project and potential scheduling and resource problems and their solutions.

7. Process decision program chart (PDPC):

This chart systematically identifies what might go wrong in a plan under development.

Seven Old Quality Tools

Any scientific decision for improving quality of a product or a process requires collection, analysis and presentation of a lot of data.

Kaoru Ishikawa of Japan had suggested seven simple tools that can be used for documentation, analysis and orgranisation of data needed for quality control. The tools are simple and can be used for more than 90 percent of industrial problems. Those seven quality tools are : Process flow chart, Control chart, Check sheet, Pareto chart, Cause and effect diagram or fish bone diagram, Histogram and Scatter diagram.

1. Flow Chart :

Process flow charts are the charts that show the sequence of operations in a process. They are also known as run charts.

The flow chart must indicate the process as it is actually proceeding and not as planned or originally visualized. Flow charts can be drawn in number of possible ways like pictures, symbols, line diagrams, etc and can be drawn to represent the entire process.

2. Control Chart :

These charts are used in statistical quality control of the process to decide whether the process as currently being run is in statistical control or to decide whether the process has the capacity to meet the specified tolerances.
When the process is in control, any variation in the data is due to some random causes and no corrective action taken out. If any process found out of control is subjected to assignable causes which needs to be investigated and rectified to avoid production of unacceptable or defective parts.

Each chart in above figure shows central mean line and lines for Upper Control Limit (UCL) and Lower Control Limit (LCL) based on statistical consideration. For the process to be within statistical control, the data obtained from testing of random samples must be within UCL and LCL.

3. Check Sheet :

Check sheet is a manual graphical method of data collection generally used for acceptance sampling.
Check sheet helps in collecting data in systematic and organized way.

Above figure shows a check sheet of reworked jobs of respective departments. As the checking continues, whenever a job is reworked, a tick or a mark is made in the correct column. This ensures fast, easy and error free data collection.

Types of check sheets -

i. Defective items check sheet.
ii. Defective location check sheet.
iii. Defective cause check sheet.
iv. Checkup confirmation check sheet.

4. Pareto Chart :

Pareto charts are based on the 20-80 rule which is named after Vilfredo Pareto in 1897. While investigating the distribution of wealth and income in Italy, Pareto discovered that, "a small percentage of any given group (20 percent) accounts for a high amount (80 percent) of a certain characteristics." This is called 20-80 or Pareto principles.
Knowing that 80 percent of the trouble is caused by  20 percent of the problems, the data is collected and is used to identify these troubles causing the problems and to take them first.

For example to know the lateness in a company is shown in above figure. A line drawn from 60 percent locates that traffic and child care needs to be taken up first for rectification.

5.  Cause and Effect Diagram :

It is also known as fish bone diagram due to its shape like fish bone. Cause and effect charts are the charts devised to study how an unacceptable part is produced. When an unacceptable part is produced, it becomes necessary to analyze the production process to identify the cause for production of such a part so that necessary corrective action can be initiated to stop production of more such parts. This is done best with the help of cause and effect diagrams.
Defects in the production may occur mainly due to machine, method, materials, measurement, men or environment as shown in fig.

In the cause and effect study, all these elements are listed and the factors causing the defect related to each of these elements are studied one after the other.

6. Histogram :

Histogram is a pictorial representation of data to show the spread or variation of set of data. It displays frequency distribution of data.

Histograms are useful to quickly identify the points where maximum variation is occurring.

7. Scatter Diagram :

A scatter diagram is a mathematical approach for studying correlation between factor that are suspected to be related to each other. These diagrams provide quick, simple and easy way to interpret such relationships.

The following steps are involved in drawing and interpreting scatter diagram.
(1) Select the two factors in which the relation is required to be studied. These factors may be detected from the cause and effect diagram for the production process.
(2)Collect the data. Data should always be collected in pairs and must be large enough to allow establishment of any correlation.
(3) Draw axes of the scatter diagram.
(4) Plot each set of data.

Thermodynamic system and its classification

A thermodynamic system is defined as a fixed mass in space under thermodynamic consideration to analyse a problem.
The system is identified by a boundary drawn around the system which may be real or imaginary. Across the boundary, the energy transfer in the form of heat and work takes place.
Shape, volume, position of boundary may change during energy exchange with the surroundings.
Everything external to the system is called surroundings or environment. 

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Thermodynamic System

A system and its surroundings together is called the universe.

Classification of Thermodynamic Systems :

Based on the mass and energy transfer between the system and the surrounding, the system can be classified as - Open system, Closed system and Isolated system.

1. Open system:

A system with mass transfer along with energy transfer across its boundaries is called an open system.
Fig a. shows open system which consists of turbine. It should be noted that the matter across the boundary of the system as the high pressure gases enter into the turbine and low pressure gases enter into the turbine and low pressure gases leave the turbine.
Also, it is not necessary that the quantity if matter within the boundaries of an open system to remain fixed.
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Open System

2. Closed system:

A system without mass transfer across its boundaries is called a closed system.
Such systems have only the energy transfer in the form of heat and work with its surroundings across the system boundary.
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Closed System

3. Isolated system:

If there is no mass and energy transfer between the system and surroundings, the system is said to be an isolated system.
Hence, according to the definition, universe is an isolated system
Handy example of isolated system is themos flask.
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Isolated System

First Angle and Third Angle Projection Methods | Engineering Drawing

To provide details of 2D drawing of any 3D object, two main types of projections are used and they are First Angle projection and Third Angle projection.
A collection of 2D drawings of any 3D object is represented with the help of orthographic projection. Orthographic projection consist of 6 views (Front, Back, Top, Bottom, Right, Left) called as principle views. Among these six orthographic views front view, right view and top view are the most commonly used to represent the orthographic projection of any object.

Method of Projection

Now, we know there are basically four quadrants. Hence to get the projections, we divide the object into four quadrants. First quadrant represents the First Angle projection of the object while third quadrant represents the Third Angle projection of the object. The principle projection planes and quadrants used to create 2D drawings can be seen in fig. 1.
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Fig. 1. Principle Projection Planes and Quadrants

Now, let us see first angle and third angle projection in details.

First Angle Projection

In first angle projection, the object is placed in between the plane of projection and the observer as shown in fig.2.
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Fig.2. Object in between Plane of projection and observer

 As explained above, in first angle projection, object is placed in first quadrant. The views are obtained by projecting the image of object in respective plane. Here you have to note down that the right hand side view is projected on the plane placed at the left of the object. After projecting the images on the respective planes, the bottom plane and the left plane is unfolded onto the front view i.e. left plane is unfolded towards left side to get Right Hand Side view on the left side of the front view. Similarly, bottom plane is unfolded towards the bottom to obtain the Top view placed below front view as shown in fig. 3.
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Fig.3. First Angle Method

Third Angle Projection

In third angle projection, the plane of projection is placed in between the object and the observer as shown in fig.4.
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Fig.4. Plane of projection in between object and observer
In this type of projection, the object is placed in third quadrant. The views are obtained by projecting the image on the respective plane as shown in fig.5.
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Fig.5. Third Angle Projection

Symbols

As per BIS standard, drawing symbol for first angle projection and third angle projection are shown in fig.6.
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Fig.6. Projection Symbol

Difference in between First Angle projection and Third Angle Projection

Due to increase in complication in drawings, second angle projection and fourth angle projection are not used. The difference between first angle projection and third angle projection is given below.
Difference between First angle and Third Angle Projection

Bourdon Presssure Guage - Pressure Measuring Device

A Bourdon pressure gauge consists of a bent tube of an elliptical cross section, a calibrated scale, gear and pinion arrangement. A typical sketch of Bourdon pressure gauge is shown in figure.
One end 'A' of the tube is sealed and its motion is transmitted to the pinion through the link E and gear.
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Bourdon Pressure Gauge

The other end 'B' of the tube is open through which the fluid pressure is transmitted to the tube. The Bourdon pressure gauge measures the pressure difference inside the tube and the atmospheric pressure.
The bent tube tends to unbend when subjected to the fluid pressure. The deformation of thee tube is transmitted from end 'A' to the pinion and the needle will show the gauge pressure of the fluid on the calibrated scale.

Design and Analysis of Rocket Nozzle

Design and Analysis of Rocket Nozzle
The functional part of rocket viz. rocket nozzle is used to channelize and accelerate the combustion products produced by the burning propellant inside rocket, in such a way that it maximizes the velocity of the exhaust at the exit. to the supersonic velocity. The nozzle converts chemical energy of propellant to kinetic energy without any moving parts. It is basically a tube with variable cross-sectional area.
Generally, nozzles are used to control the flow rate, direction, mass, speed, shape and the pressure of the exhaust stream that emerges from them. The nozzle converts high pressure, low velocity and high temperature gas in the combustion chamber into high velocity of gas of low pressure and temperature thus producing the required thrust for the rocket to propel.
Design and analysis of rocket nozzle | www.enggarena.net
Design and analysis of Rocket Nozzle

Rocket engine nozzle is propelling nozzle (usually of the de Laval type) used in rocket engine to expand and accelerate the combustion gases produced by burning propellant so that the exhaust gases exit the nozzle at hypersonic velocities. The convergent and divergent type of nozzle is called as de Laval nozzle. Throat is the area with minimum area in convergent divergent nozzle. The divergent part of the nozzle is known as nozzle exit. In the convergent section, the pressure of the exhaust gases will increase and as the hot gases expand through the diverging section attaining high velocities from continuity equation.
The analysis of rocket nozzle involves the concept of steady, one dimensional compressible fluid flow of an ideal gas. The goal of the rocket nozzle design is to accelerate the combustion products to as high exit velocity as possible. This is achieved by designing the necessary geometric nozzle profile with the condition that isentropic flow is considered to be flow that is dependent only upon cross sectional area. Therefore, in actual nozzle it is necessary to minimize the frictional effect, flow disturbances and conditions that can lead to shock losses. In addition, heat transfer losses should be minimize. That means it should be thermal resistant.
In this way, the properties of the flow are near isentropic and are simply affected only by the changing cross sectional area as the fluid flows through the nozzle. Space shuttle uses some of the largest de Laval nozzles in the solid rocket boosters. They are designed so as to optimize the weight and the performance.
In this project study is conducted to study the various configurations and geometries of de Laval nozzle with respect to the available technologies been used in the world. Further an effort is made to analyse the flow of the gases through a space shuttle nozzle using commercially available softwares.