Stress Strain Graph for Mild Steel explained

Stress:

When any object of certain material is subjected to tensile or compressive or shear force, there may be a chance that its dimension will be affected.
If the dimension of a material is changed due to application of forces we can say that the material is under stress or experiencing the state of stress.

Stress is defined as the Force per unit cross section area.
Stress = F/A

Stress is mainly of two types normal stress and shear stress.

Normal Stress:

When the force applied is perpendicular to the cross section of the object then the stress is known as normal stress. (The force can be tensile or compressive)

Shear Stress: 

When the force applied is parallel to the material cross section then the stress is known as shear stress.

Stress Strain Graph for Mild Steel (Ductile Material)

If a relatively small force is applied to ductile material steel and it starts to deform (that means that the steel is in stress and we can measure the strain) then we will a curve which is initially a straight line. After plotting stress vs strain we will get the relation. 

In this stress strain graph of mild steel we will find a straight line , that is up to point A from the origin. From that experimental graph we can conclude that stress is proportional to strain. Up to point A is the limit of proportionality. Within the elastic limit the deformation of the steel will be temporary. After the withdrawal of the force the steel bar will return to its original shape. If the force is increased then steel bar will be deformed elastically up to point B. This is the elastic limit (Point B). Beyond that if the force is increased then the plastic deformation will start and we will have upper yield point C and lower yield point D. For further increase in the force material will experience fracture or breaking stress (Max. Ultimate Stress). From this graph we get Young's modulus of elasticity for steel which is 210 GPa. This graph also associates modulus of resilience as well as modulus of toughness. 

Please Read: 

Stress-Strain Relationship 
Connecting Rod Bearing Failure analysis 
Heat Treatment of Steel 
Different Mechanical Properties of Materials 

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Plastic Extrusion Process Principles

Extrusion Process Principles

Extrusion process is very common in the plastic industry. It is used for high volume plastic production. In extrusion process the color pigments along with other performance enhancing additives are combined with resin which is then pushed through the rotating screws. The heat and pressure generated within the barrels of screw is dispersed and melts the plastic elements. Thus a homogeneous mixture is produced. A cool die is usually placed at the end of the mixture. After passing through the die the mixture is ready to experience the finishing operation which may include pelletizing, calendaring or other processes. 

The arrangements shows a motor which runs the gear box. The speed is used by this gear reducer box. Which then moves the screw. The metal ingredients is poured through the hopper. The feeding of metal is done in the feeding zone. Then with the increased pressure and temperature of the screw melts the elements in the melting zone. The next part is the melt pumping zone which increases the pressure of the liquid. This pressurized liquid is then pushed through the filter. Then the molten metal flows through the die and cooled. The thermocouple is set at different points to measure the temperature. The figure of the whole process is shown below. Click on it to have a better view . 

Advantages of Plastic Extrusion Process

One of the main advantages of the extrusion process is it can produce pipes of any length. It is continuous. High production volumes with very low cost per pound. The melting is very efficient. The mixing of the ingredients is very good. Different types of raw materials can be used. It uses thermoplastics which can be reused.

Disadvantages of Plastic Extrusion Process

Highly complicated parts are very not suitable for production in extrusion process. It can only produce the parts which have uniform cross sections. 

Please Read : 

• Different Types of Plastics and Their Advantages and Disadvantages
• A complete Guide to Casting Process 

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Match Plate Pattern - Used in Casting (With diagram)

What is Match - Plate Pattern 

The match plate pattern is almost similar to the mounted pattern but it can have part of the casting in the cope and part in the drag like split piece pattern. These parts are generally attached to the plate / board in opposite sides in the perfect positions. When the plate is removed and mold is in close position the cavities in the cop and drag match perfectly. The mounting procedure matches the procedure of one sided mounted plate.

schematic of match plate pattern

Characteristics of Match Plate Pattern 

• It is split pattern 
• Cop and Drags on the opposite site of the metallic (generally) plate. 
• The gates are runners are on the match plate. 
• Can be used for large number of casting with very little hand work. 
• A match plate can be single pattern or a combination of many small patterns
• Example : IC engine piston rings can be produced by match plate pattern 

Important parts of Match Plate Patterns  

Cope and Drag Mounts

• Two separate pattern mounts are there.
• One is fitted to the female guides (for drag) other is fitted with pins (for cope). This must match the profile of the flask that is used.
• The half part of the pattern associated by the cope is attached to the cope mount and drag part pattern is attached to the drag mount.
• Cope and drag portions are manufactured disparately and combined together for pouring.
• Generally one molder makes copes other makes drags.
• Cope and drag mounts are also known as tubes.
• These (cope and drag mounts) are very similar when producing large castings. 

cope and drag mounts in match plate pattern 

Follow board

• It is a board with a cavity or socket.
• The cavity must conform to the shape of the pattern.
• It also defines the parting surface of the drag.
• Materials: It can be made of plaster or metal. If sand is used to manufacture follow board then it is called dry sand match.
• When the drag half of the mold is made the pattern rests on the follow board.
• It creates the correct sand parting.
• Pattern is rammed in the drag and follow board is removed.
• The follow board is replaced by the cope.
• A simple follow board may have a hole in it so that the pattern rests firmly when the drag is being rammed.   

follow board

simple follow board

Please Read :

• Different types of casting defects 
• What is casting ? Main application of castings 
• different types of patterns that are used on the sand casting process. 
• different types of molding sand
• properties of various natural and synthetic molding sands
• Comparison of different casting processes. 
• Advantages and disadvantages of centrifugal castings.  

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Magnetically Impelled Arc Butt Welding Principles

Magnetically impelled arc butt (MIAB) welding (sometimes referred to as rotating arc welding) is a rapid, clean, and reliable arc welding process that employs forging to produce  the finished weld. As such, it is classified as an electric arc welding process since that is the energy source for producing melting or fusion, even though pressure from forging is needed to complete the weld. It is thus a fusion arc pressure welding process, and, in that way, is related to arc stud welding  ( not described in this article. )

The MIAB welding process is well established in Europe (especially Eastern Europe) and the independent  states of  the  former Soviet Union, finding application in  the  automotive  industry for  the fabrication of tubular-section butt welds and, to a lesser extent, tube-to-plate welds. Tubes can have circular or non-circular cross sections, with walls ranging from 0.5 to 5 mm or more (0.020 to 0.200 in.) thick. Steel as well as aluminum alloy has been  welded successfully in mass production, producing welds with exceptional quality even for safety-critical applications.

Magnetically Impelled Arc Butt Welding Principles 

In practice, MIAB welding  is fully automated. An arc drawn between aligned but properly gapped tube ends is impelled to move (rotate) around the joint  line by an interaction of  the arc current  and  an externally  applied magnetic field , hence the name. Once the arc has heated the ends of the tubes to cause localized melting and adjacent softening in the heat-affected zone, the parts are forged together. This expels most of the molten metal present and a solid-phase  bond is formed. The principle of operation is shown  schematically in  Figure 1 ; typical placement of the magnets used to apply the propelling force to the arc is shown in Figure 2

Figure 1 : MIAB principles 

Figure 2 : MIAB schematic 

Benefits of MIAB

The  major benefits of MIAB welding are (1)  no rotation of either  component  (thereby  overcoming  problems  with  asymmetrical  parts  encountered with many friction welding processes), (2) short welding times (e.g., 2-4 s for 2 to 4-mm CO.040-  to 0.080-in.]-thick low-carbon steel tube), (3) low
material loss, (4) low fumes and  spatter, and (5) relatively low required arc current.

As opposed to flash and upset welding , MIAB welding does not use resistance to accomplish heating at the joint, but, rather, an electric arc. This makes  it an arc rather  than a  resistance welding process. The fact that forging  removes  most  molten  metal  suggests that  the  process  could  be considered non-fusion; after  all,  the role of the  liquid is  largely  fluxing . The  process is considered  a  non-consumable electrode arc process because the intent is not to consume the parts being welded and used as electrodes, but to preserve those parts.

Please Read :

• Different types of welding defects.
• How to easily understand TIG welding Basics 
• Advantages of TIG welding 
• TIG welding Principles in Easy language 
• Welding Electrodes Explained 
• MIG welding principles 
• Aluminothermic or Thermit Welding Principles  
• Submrged Arc Welding 
• Flux shielded metal arc welding process principles 
• Resistance Projection Welding 
• Resistance Spot Welding 
• Resistance Seam Welding 
• TIG Aluminum Welding Advantages  made easy !
• Advanced TIG welding operations 

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Abrasive Jet Machining (AJM) Process Advantages and Disadvantages

Abrasive Jet Machining (AJM) Principles 

In abrasive jet machining process, a focused steam of abrasive particles (of size 10 to 40 microns) carried by high pressure gas or air at a velocity of about 150 to 300 m/sec is made to impinge on the work surface through a nozzle, and the work material is removed by erosion by the high velocity abrasive particles. The inside diameter (ID) of the nozzle through which abrasive particles flow is about 0.18 to 0.80 mm and the stand-off distance (i.e. distance between nozzle tip and workpiece) is kept about 0.3 to 20.0 mm. The process can be easily controlled to vary the metal removal rate which depends on flow rate and size of abrasive particles. This process is best suited for machining super alloys and refractory type of materials, and also machining thin sections of hard materials and making intricate hard holes. The cutting action is cool because the carrier gas serves as coolant. 

When an abrasive particle (like Al2O3 or SiC) having sharp edges hits a brittle and fragile material with a high speed, it makes dent into the material and lodges a small particle from it by a tiny brittle fracture. The lodged out or wear particle is carried away by the air or gas. The operating elements in AJM are abrasive, carrier gas and the nozzle as schematically shown in the following Figure

Abrasive Jet Machining (AJM) Principles 

The distance between the nozzle tip and the work surface has great influence on the diameter of cut, its shape and size and also rate of material removal. The following Figure shows the variation in the diameter of cut with change in the stand off distance (SOD). It is evident that the SOD changes the abrasive particles spreads (i.e. covers wider area) on the work surface and consequently increases the diameter of the cut.

The basic Units of AJM

The basic unit is schematically shown in following Figure. It consists of gas supply system (compressor), filter, pressure regulator, mixing chamber, nozzle assembly and the work holding device. In the mixing chamber, the abrasive is allowed to flow into the gas stream. The mixing ratio is generally controlled by a vibrator. The particle and gas mixture comes out of the nozzle inside the machining chamber of the machine tool unit. The feed motion can be given either to the work holding device or to the nozzle. 

AJM setup

Please read :

• Water Jet Machining Process .
• Laser Beam Machining 
• Electrical Discharge Machining (EDM) Principles 
• Electrochemical machining process 

Abrasive Jet Machining (AJM) Advantages:

• This process is quite suitable for machining brittle, heat resistant and fragile materials like, glass, ceramic, germanium, mica etc. 
• It can be utilized for cutting, drilling, polishing, deburring, cleaning etc. of the materials. 
• The depth of damage to the surface is very little. 
• Holes of intricate shapes could be produced efficiently.
• The surface machined can have good finish (by controlling the grain size mainly). 

AJM Disadvantages: 

The materials removal rate is low. For example, for glass, it is 0.0164 cm3/min. 

• The tapering of hole especially, when the depth of the hole is more, becomes almost inevitable. 
• A dust collecting chamber is a basic requirement to prevent atmospheric pollution to cause health hazards.
• The abrasive particles may remain embedded in the work surface. 
• Abrasive particles cannot be reused.

AJM Applications:

• Abrasive jet machining is best suited for machining brittle and heat sensitive materials like glass, quartz, sapphire, ceramics etc,
• It is used for drilling holes, cutting slots, cleaning hard surfaces, deburring, polishing etc. 

Please Read :

• Different types of welding defects.
• How to easily understand TIG welding Basics 
• Advantages of TIG welding 
• TIG welding Principles in Easy language 
• Welding Electrodes Explained 
• MIG welding principles 

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Industrial Engineering and Production Management Questions and Answers Part 5

Here are some basic questions and answers about Industrial Production Engineering Hope these will help the students of IPE and Mechanical Engineering This is the part 2 of the series of questions. New posts with new questions will be posted regularly. Thanks . And comment in the respective sections for any query about mechanical engineering.  If you want the explanation of the answers then you are very much welcome to contact me through the contact us section. Cheers !

Read These : 
Industrial Engineering and Production Management Questions and Answers Part 1
Industrial Engineering and Production Management Questions and Answers Part 2 
Industrial Engineering and Production Management Questions and Answers Part 3
Industrial Engineering and Production Management Questions and Answers Part 4
Industrial Engineering and Production Management Questions and Answers Part 6

Industrial Engineering and Production Management Questions and Answers 

1. How to calculate The allowed time for a job ? 
ans- Standard time + policy allowance . 

2. How many fundamental hand motion is involved in micromotion study ? 
ans- 16. 

3. There are three activities in a PERT network on critical path. The mean times are 3,8 and 6. The standard deviations are 1,2 and 2 respectively. What is the probability that the project will be completed in 20 days ? 
ans- 0.84 

4. Scheduling determines what ? 
ans- Programme needed for the operation. 

5. A system of organisation was introduced by F. W. Taylor . It is known as - 
ans- Functional organization. 

6. What is the sequence of phases in value engineering ? 
ans- 1. creative phase 2. information phase 3.  investigation phase and 4. evaluation phase. 

7. When valve analysis is appreciated ? In large production scale or small production scale? 
ans- In large production scale. 

8. What are the conditions for using conveyors for transportation ? 
ans - loads should be uniform , no variation the routs and continuous movement of the material. 

9. Planning and scheduling of Mass production manufacturing differs from that of job order manufacturing . True or False ? 
ans - True . 

10. What information does scheduling gives us ? 
ans - The perfect time for starting the job and the amount of work that should be completed in a certain amount of time. 

11. Which type of layout is used for manufacturing steam turbine ? 
ans- fixed position layout, 

12. What information does Gantt chart give us ? 
ans- Information about production scheduling. 

13. When materials are checked in perpetual inventory control ? 
ans- when material reaches its minimum value. 

14. Why merit rating is used ? 
ans - To evaluate workers performance in a work. 

15. Do you think that acceptance sampling is good for mass production ? 
ans- Yes. 

16. What is Queuing theory  ? 
ans - It is the theory for determining the waiting times and queue lengths by using mathematical study. It is basically the study of waiting lines .  

17. What is the standard time for a job ? 
ans - delay contingency allowance plus the total work content time. 

18. What is the full form of PERT ? 
ans - Programme Evaluation and Review Technique

20. When bonus is paid to a worker in wage incentive system  named Emerson's efficiency plan ? 
ans - when his or hers output efficiency exceeds 67%. 

Thanks. These Questions will be helpful as these can be the practice questions for mechanical engineering job interview.

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Industrial Engineering and Production Management Questions and Answers Part 3

Here are some basic questions and answers about Industrial Production Engineering Hope these will help the students of IPE and Mechanical Engineering This is the part 2 of the series of questions. New posts with new questions will be posted regularly. Thanks . And comment in the respective sections for any query about mechanical engineering.  If you want the explanation of the answers then you are very much welcome to contact me through the contact us section. Cheers !

Read These : 
Industrial Engineering and Production Management Questions and Answers Part 1
Industrial Engineering and Production Management Questions and Answers Part 2 
Industrial Engineering and Production Management Questions and Answers Part 4 
Industrial Engineering and Production Management Questions and Answers Part 5
Industrial Engineering and Production Management Questions and Answers Part 6

Industrial Engineering and Production Management Questions and Answers 

1. What is Just-In-Time theory ? 

ans- Just-in-time, or lean manufacturing, is a production management theory formed for production efficiency by  the continuous reduction of waste. JIT includes the reduction of inbound inventory by giving a delivery schedule to suppliers and thus minimizing outbound stocks. It reduces the creation of scrap materials and diminished the wasted time. It improves cash flow and sales margin. 

2. What do you mean by flow control ? 

ans- Flow control is optimized production technology.  In the production process It  emphasizes on the efficient flow of material. 

3. Static product layout is also known as - 

ans- Fixed position layout. 

4. What is the best process of determining standard time in a complex job system  ?

ans-  by the analysis of standard data system

5. How the cost slope is determined in In CPM ? 

ans-  ( Crash cost - Normal cost ) /(Normal time - Crash time)

6. How to construct a network diagram ? 

ans -  For each activity only one arrow should be used > In the diagram dangling must be avoided > No consumption  of time and resources by dummy activity. 

7. Why simplex method is used ?

ans- for linear programming . 

8. What is the basis of Halsey plan ? 

ans- It is a wage incentive plan which ensures minimum wage for a worker and bonus is paid for the fixed percentage of time he/she saved. 

9. What is job evaluation ? 

ans- Evaluating the value of a job in relation to other jobs . 

10. How break-even analysis is formed ? 

ans- fixed cost + variable cost.  

11. Examples of Direct and Indirect costs - 

ans - Direct - Wages. Indirect - Electricity Bills . 

Thanks. These Questions will be helpful as these can be the practice questions for mechanical engineering job interview.

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Industrial Engineering and Production Management Questions and Answers Part 2

Here are some basic questions and answers about Industrial Production Engineering Hope these will help the students of IPE and Mechanical Engineering This is the part 2 of the series of questions. New posts with new questions will be posted regularly. Thanks . And comment in the respective sections for any query about mechanical engineering.  If you want the explanation of the answers then you are very much welcome to contact me through the contact us section. Cheers !

Read These : 
Industrial Engineering and Production Management Questions and Answers Part 1
Industrial Engineering and Production Management Questions and Answers Part 3 
Industrial Engineering and Production Management Questions and Answers Part 4 
Industrial Engineering and Production Management Questions and Answers Part 5
Industrial Engineering and Production Management Questions and Answers Part 6

Industrial Engineering and Production Management Questions and Answers 

1. Do you think that PERT is an event oriented technique ? Yes or No . 
ans - Yes. 

2. Which  chart gives simultaneous information of work progress and machine loading?
ans- Man-machine chart. 

3. In value engineering what is the meaning of value ? 
ans- utility of the product

4. Why work sampling is applied ? 
ans-  for estimating the percentage utilization of machine tools, estimating percentage time, finding time study in certain situations. 

5. Production costs means - 
ans- Prime cost + Factory overhead . 

6. A systematic job improvement sequence consists - 
ans- motion study + job enrichment + time study 

7. Do you think that line balancing problem and transportation problem can be solved by Linear programming model  ? 
ans - Yes . 

8. Which chart gives an estimation of amount of materials handling between various work stations ? 
ans- travel chart. 

9. which is the device used for  lifting or lowering objects suspended from a hook at the end of retractable chains or cable ? 
ans - Hoist. 

10. What a flow diagram generally shows ? 
ans - The path followed by materials and men while doing a job. 

Thanks. These Questions will be helpful as these can be the practice questions for mechanical engineering job interview.

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Industrial Engineering and Production Management Questions and Answers Part 1

Here are some basic questions and answers about Industrial Production Engineering. Hope these will help the students of IPE and Mechanical Engineering. This is the part 1 of the series of questions. New posts with new questions will be posted regularly. Thanks . And comment in the respective sections for any query about mechanical engineering.  If you want the explanation of the answers then you are very much welcome to contact me through the contact us section. Cheers !

Read These :
Industrial Engineering and Production Management Questions and Answers Part 2  
Industrial Engineering and Production Management Questions and Answers Part 3 
Industrial Engineering and Production Management Questions and Answers Part 4 
Industrial Engineering and Production Management Questions and Answers Part 5
Industrial Engineering and Production Management Questions and Answers Part 6

Industrial Engineering and Production Management Questions and Answers 

1. In Time study , Why the rating factor is applied ? Ans - fixation of incentive rate


2. Why Gantt Chart is used ? Ans - for production scheduling. 


3. What is the main purpose of value engineering ? ans - to minimize the cost without changing the quality of the product. 


4. Why Scientific Layout is used ? Ans - Minimizing production delay, increasing floor area and ensuring production quality. 


5. What Work study involues ? 
Ans -  work measurement and method study . 

6. Why A-B-C analysis is used ? 
Ans - For Inventory Control 

7. Which class of items are generally large in number in In A-B-C analysis ? 
Ans - C . 

8. PERT analysis depends on - 
Ans - Optimistic, Pessimistic and most likely time. 

9. Why Process layout is used ? 
Ans- for avoiding excessive multiplication of facilities. 

10. What is an element of Queuing Theory ? 
ans - Waiting time. 

11. What PERT requires ? 
ans- triple time estimate.

12. According to break even analysis, how total cost is got ? 
ans- by summing fixed cost and variable cost. 

13. When Bar Chart is more appropriate to use ? 
ans- for minor works. 

14. For an activity how Probabilistic time is calculated ? 
ans - By optimistic, pessimistic and most likely time. 

15. Where Line organization is suitable ? 
ans - for small organization.  

Thanks. These Questions will be helpful as these can be the practice questions for mechanical engineering job interview. 

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