The 8D Problem-Solving Process

Solving Major Problems in a Disciplined Way (Also known as Global 8D Problem-Solving)

When your company runs into a major problem, you need to address it quickly. However, you also need to deal with it thoroughly and ensure that it doesn't recur - and this can take a lot of effort and elapsed time. The 8D Problem-Solving Process helps you do both of these seemingly-contradictory things, in a professional and controlled way. In this article, we'll look at the 8D Problem-Solving Process, and we'll discuss how you can use it to help your team solve major problems.

Solve problems quickly and effectively. © iStockphoto/3dsguru

Origins of the Tool:

The Ford Motor Company developed the 8D (8 Disciplines) Problem-Solving Process, and published it in their 1987 manual, "Team Oriented Problem Solving (TOPS)." In the mid-90s, Ford added an additional discipline, D0: Plan. The process is now Ford's global standard, and is called Global 8D.

Ford created the 8D Process to help teams deal with quality control and safety issues; develop customized, permanent solutions to problems; and prevent problems from recurring. Although the 8D Process was initially applied in the manufacturing, engineering, and aerospace industries, it's useful and relevant in any industry.

The eight disciplines are shown in figure 1, below:

Figure 1: The 8D Problem-Solving Process

The 8D Process works best in teams tasked with solving a complex problem with identifiable symptoms. However, you can also use this process on an individual level, as well.

Applying the Tool

To use the 8D Process, address each of the disciplines listed below in order. Take care not to skip steps, even when time is limited; the process is only effective when you follow every step.

Discipline 0: Plan

Before you begin to assemble a team to address the problem, you need to plan your approach. This means thinking about who will be on the team, what your time frame is, and what resources you'll need to address the problem at hand.

Discipline 1: Build the Team

You should aim to put together a team that has the skills needed to solve the problem, and that has time and energy to commit to the problem-solving process.

Keep in mind that a diverse team is more likely to find a creative solution than a team of people with the same outlook (although if outlooks are too diverse, people can spend so much time disagreeing that nothing gets done.)

Create a team charter that outlines the team's goal and identifies each person's role. Then, do what you can to build trust and get everyone involved in the process that's about to happen.

If your team is made up of professionals who haven't worked together before, consider beginning with team-building activities to ensure that everyone is comfortable working with one another.

Discipline 2: Describe the Problem

Once your team has settled in, describe the problem in detail. Specify the who, what, when, where, why, how, and how many; and use techniques like CATWOE and the Problem-Definition Process to ensure that you're focusing on the right problem.

Start by doing a Risk Analysis - if the problem is causing serious risks, for example, to people's health or life, then you need to take appropriate action. (This may include stopping people using a product or process until the problem is resolved.)

If the problem is with a process, use a Flow Chart, Swim Lane Diagram, or Storyboard to map each step out; these tools will help your team members understand how the process works, and, later on, think about how they can best fix it.

Discovering the root cause of the problem comes later in the process, so don't spend time on this here. Right now, your goal is to look at what's going wrong, and to make sure that your team understands the full extent of the problem.

Discipline 3: Implement a Temporary Fix

Once your team understands the problem, come up with a temporary fix. This is particularly important if the problem is affecting customers, reducing product quality, or slowing down work processes.

Harness the knowledge of everyone on the team. To ensure that each person's ideas are heard, consider using brainstorming techniques such as Round Robin Brainstorming or Crawford's Slip Writing Method, alongside more traditional team problem-solving discussions.

Once the group has identified possible temporary fixes, address issues such as cost, implementation time, and relevancy. The short-term solution should be quick, easy to implement, and worth the effort.

Discipline 4: Identify and Eliminate the Root Cause

Once your temporary fix is in place, it's time to discover the root cause of the problem.
Conduct a Cause and Effect Analysis to identify the likely causes of the problem. This tool is useful because it helps you uncover many possible causes, and it can highlight other problems that you might not have been aware of. Next, apply Root Cause Analysis to find the root causes of the problems you've identified.

Once you identify the source of the problem, develop several permanent solutions to it.
If your team members are having trouble coming up with viable permanent solutions, use the Straw Man Concept to generate prototype solutions that you can then discuss, tear apart, and rebuild into stronger solutions.

Discipline 5: Verify the Solution

Once your team agrees on a permanent solution, make sure that you test it thoroughly before you fully implement it, in the next step.

Consider:

• Conducting a Failure Mode and Effects Analysis (FMEA) to spot any potential problems.
  
  
• Using Impact Analysis to make sure that there will be no unexpected future consequences.
  
  
• Using Six Thinking Hats to examine the fix from several different emotional perspectives.

Last, conduct a Blind Spot Analysis to confirm that you and your team haven't overlooked a key factor, or made an incorrect assumption about this solution.

Discipline 6: Implement a Permanent Solution

Once your team reaches consensus on the solution, roll your fix out. Monitor this new solution closely for an appropriate period of time to make sure that it's working correctly, and ensure that there are no unexpected side effects.

Discipline 7: Prevent the Problem From Recurring

When you're sure that the permanent solution has solved the problem, gather your team together again to identify how you'll prevent the problem from recurring in the future.

You might need to update your organization's standards, policies, procedures, or training manual to reflect the new fix. You'll likely also need to train others on the new process or standard. Finally, you'll need to consider whether to change your management practices or procedures to prevent recurrence.

Discipline 8: Celebrate Team Success

The last step in the process is to celebrate and reward your team's success. Say "thank you" to everyone involved, and be specific about how each person's hard work has made a difference. If appropriate, plan a party or celebration to communicate your appreciation.

Before the team disbands, conduct a Post-Implementation Review to analyze whether your solution is working as you thought, and to improve the way that you solve problems in the future.

Key Points

In the late 1980s, Ford Motor Company developed the 8D (8 Disciplines) Problem-Solving Process to help manufacturing and engineering teams diagnose, treat, and eliminate quality problems. However, teams in any industry can use this problem-solving process.

The eight disciplines are:

0. Plan.
1. Build the Team.
2. Describe the Problem.
3. Implement a Temporary Fix.
4. Identify and Eliminate the Root Cause.
5. Verify the Solution.
6. Implement a Permanent Solution.
7. Prevent the Problem From Recurring.
8. Celebrate Team Success.

The 8D Problem-Solving Process is best used with a team solving complex problems; however, individuals can also use it to solve problems on their own.

Courtesy:  Mind Tools

Efficiency, BP, BSFC, BMEP calculation -Two Stroke, Single Cylinder Petrol Engine

1.     Torque, T = 9.81 x W x R Effective Nm.

Where R Effective = (D + d)/2 m,

W (Load) = ( S1 S2) Kg.

2.     Brake Power, B P = ( 2πN T ) / 60, 000 KW

Where N = rpm,

T = Torque Nm,

3.     Indicated Power, I P = n ( Pm x L Stroke x A x N’) / 60,000 KW

Where Pm = Mean Effective Pressure N/ m²,

L Stroke = Stroke m,

A (Cross Section of the Cylinder) = (πD²_Bore)/ 4 m²,

N’ (Number of Power Strokes/ min.)

= N/ 2 per min. (For Four Stroke Engine)

=N per min. (For Two Stroke Engine)

N = rpm, and

n = Number of Cylinders.

4.    Fuel Consumption, m f = ( 50 ml x 10⁶ x ρ Fuel ) / ( t ) Kg/Sec.

Here; 1 ml = 10^-3 liters, and 1000 liters = 1m³

So 1 ml = 10^-6 m³

5.     Brake Mean Effective Pressure, BMEP = (BP x 60,000)/ ( L Stroke x A x N’) N/ m2

Where L Stroke = Stroke m,

A (Cross Section of the Cylinder) = (π D²_Bore)/4 m²,

N’ (Number of Power Strokes/ min.)

= N/ 2 per min. (For Four Stroke Engine.)

= N per min. (For Two Stroke Engine)

N = speed in rpm.

6.     Brake Specific Fuel Consumption, BSFC = ( mf x 3600 ) / BP Kg/ KW . hr

7.     Indicated Specific Fuel Consumption, ISFC = ( mf x 3600 ) / IP Kg/ KW .hr

8.     Indicated Thermal Efficiency, η Indicated Thermal = ( IP x 100 ) / (mf x C.V. )%

9.    Brake Thermal Efficiency, η Brake Thermal = ( B P x 100 ) / (m_f x C.V. ) %

10. Mass of the Air, m Air = C_d Ao √2 g Δh ρ Air ρ Water Kg/ Sec ;

Where Cd ( Coefficient of Discharge ) = 0.6,

ρ_Air= ( Pa x 102 ) / ( R x Ta ) Kg/m³

Ao ( Area of Orifice ) = (π do ²)/ 4 m²,

Pa = 1.01325 Bar,

R = 0.287 KJ/ Kg K .

Ta = ( ta + 273 ) K,

ta = Ambient Temperature O C

11.  Air Fuel Ratio, A/F = ( m Air / m_f ) Kg/ Kg of Fuel

12.  Volumetric Efficiency, η Volumetric = ( VAir x 100 )/ Vs %

Where VAir ( Volume of air inhaled/ Sec.) = ( m Air / ρ Air ) m3/ Sec.

Vs ( Swept Volume/ Sec.) = n . ( L Stroke . A.. N’ )/ 60 m3/ Sec.,

And Volume of fuel is Neglected (Based on free air conditions),

A (Cross Section of the Cylinder) = (π D²Bore)/ 4 m²,

L Stroke = Stroke in m,

N’ (Number of Power Strokes/ min.)

= N/ 2 per min. (For Four Stroke Engine)

= N per min (For Two Stroke Engine)

N = speed in rpm., and n = Number of Cylinders.

13.    Mechanical Efficiency, η_mechanical = BP / IP

The BSFC calculation (in metric units) (Wikipedia)

To calculate this rate, use the formula
Where:

r is the fuel consumption rate in grams per second (g·s^-1)

P is the power produced in watts where P = τω

ω is the engine speed in radians per second (rad·s^-1)

τ is the engine torque in newton meters (N·m)

The resulting units of BSFC are grams per joule (g·J⁻¹)
Commonly BSFC is expressed in units of grams per kilowatt-hour (g/(kW·h)). The conversion factor is as follows:

BSFC [g/(kW·h)] = BSFC [g/J]×(3.6×10⁶)

Engine formulas

Cylinder Swept Volume (V_c):

where:

            V_c= cylinder swept volume [cm³ (cc) or L]

            A_c = cylinder area [cm² or cm²/100]

            d_c = cylinder diameter [cm or cm/10]

            L = stroke length (the distance between the TDC and BDC) [cm or cm/10]

BDC = Bottom Dead Center

            TDC = Top Dead Center

* Increase the diameter or the stroke length will increase the cylinder volume, the ratio between the cylinder diameter/cylinder stroke called “bore/stroke” ratio.

- “bore/stroke” >1 is called over square engine, and is used in automotive engines

- “bore/stroke” =1 is called square engine

- “bore/stoke” <1 is called= under square engine, and is used in tractor engine

Engine Swept Volume (V_e):

where:

            V_e = engine swept volume [cm³ (cc) or L]

            n = number of cylinders

            V_c = cylinder swept volume [cm³ (cc) or L]

A_c = cylinder area [cm² or cm²/100]

d_{c =}  cylinder diameter [cm or cm/10]

* The units of cylinder swept volume is measured in (cm³, cubic centimeter (cc), or liter)

- V_e  for small engines, 4 cylinder engines is (750 cc:1300 cc)

- V_e for big engine, 8 cylinder engines is (1600 cc:2500 cc)

Compression Ratio (r):

where:

            r = compression ratio

            V_s = cylinder swept volume (combustion chamber volume) [cc, L, or m³]

            V_c = cylinder volume     [cc, L, or m³]

* Increase the compression ratio increase engine power

- r (gasoline engine) = 7:12, the upper limit is engine pre ignition

- r (diesel engine) = 10:18, the upper limit is the stresses on engine parts

Engine Volumetric Efficiency (_hv):

where:

            h_V  = volumetric efficiency

            V_air = volume of air taken into cylinder [cc, L, or m³]

            V_c = cylinder swept volume [cc, L, or m³]

* Increase the engine volumetric efficiency increase engine power

- Engine of normal aspiration has a volumetric efficiency of 80% to 90%

- Engine volumetric efficiency can be increased by using:

(turbo and supper charger can increase the volumetric efficiency by 50%)

Engine Indicated Torque (T_i):

where:

            T_i = engine indicated torque [Nm]

            imep = indicated mean effective pressure [N/m²]

            A_c = cylinder area [m²]

                L = stroke length [m]

            z = 1 (for 2 stroke engines), 2 (for 4 stroke engines)

n = number of cylinders

θ = crank shaft angle [1/s]

Engine Indicated Power (P_i):

,                       

where:

            imep = is the indicated mean effective pressure [N/m²]

            A_c = cylinder area [m²]

            L = stroke length [m]

            n = number of cylinders

            N = engine speed [rpm]

            z = 1 (for 2 stroke engines), 2 (for 4 stroke engines)

            V_c = cylinder swept volume [m³]

            V_e = engine swept volume [m³]

            T_i = engine indicated torque [Nm]

            ω = engine angular speed [1/s]

Engine Mechanical Efficiency (h_m):

 

where:

            h_m = mechanical efficiency

            P_b = engine brake power [kW]

            P_i = engine indicated power [kW]

            P_f = engine friction power [kW]

Engine Specific Fuel Consumption (SFC):

where:

            SFC = specific fuel consumption [(kg/h)/kW, kg/(3600 s x kW), kg/(3600 kJ)]

            FC = fuel consumption [kg/h]

            P_b = brake power [kW]

Engine Thermal Efficiency (_hth):

 

where:

            h_th = thermal efficiency

            P_b = brake power [kW]

            FC = fuel consumption [kg/h = (fuel consumption in L/h) x (ρ in kg/L)]

            CV = calorific value of kilogram fuel [kJ/kg]

            ρ = relative density of fuel [kg/L]

What is Supply Chain Management? (ASU-WPC-SCM)

This module introduces viewers to the field of supply chain management. It describes the complex supply chain of a simple product, a bottle of water. The video also illustrates the importance of supply chain managers and their skill sets in our modern global economy for both manufacturing and service industries. In defining supply chain management, the video also hopes to educate and inspire business students, young and old, about the opportunities available to those with supply chain management degrees. This is the first installment in Arizona State University's twelve-part introduction to supply chain management video series. ASU, the W. P. Carey School of Business, and the Supply Chain Management Department are proud and happy to share this video series with supply chain management departments, supply chain instructors, career specialists in high schools and universities, as well as industry leaders in an effort to inspire a new generation of supply chain management professionals across the country and around the world.

Moulding Machines

Moulding Machines:

Moulding processes may be classified as hand moulding or machine moulding according to whether the mould is prepared by hand tools or with the aid of some moulding machine. Hand moulding is generally found to be economical when the castings are required in a small number.

Advantages:

· When the number of castings is substantial, the additional cost of metallic patterns and other equipment is compensated by the high rate of production, and the overall cost per piece works out lower than in the case of hand moulding.

· It affords great saving in time, especially when a large number of similar castings in small sizes are required.

· A semi-skilled worker can do the machine job whereas hand moulding requires skilled craftsmanship.

· The castings obtained are more uniform in size and shape and more accurate than those obtained by hand moulding due to steadier lift of the pattern.

Types of Moulding machine:

1. Hand Operated molding machine

a. Pattern draw type

b. Pattern draw and Squeeze type

c. Pin Lift type machine

d. Roll Over type machine

2. Power operated Molding Machine

a. Squeeze machine

b. Jolt machine

c. Jolt squeeze machine

d. Jolt squeeze roll over pattern draw machine

e. Sand Slinger

Squeeze machine

A squeeze machine is very useful for shallow patterns. A squeezer (squeeze head) plate or presser board slides inside the flask to compress the sand above and around the pattern.

For squeezing action the squeeze piston may by forced upward, pushing the flask up against the squeezer or presser board the presser board being forced into the flask.

The sand is rammed harder at the back of the mould and softer on the pattern face. In other words sand has greatest density at the surface where pressure is applied to sand and sand density decreases progressively towards the pattern.

Moulding force (M_f) = P (π. d²/4)-W

Where, P – Pressure in squeeze cylinder

d – Piston diameter

W – Weight of flask pattern and sand

Jolt-Squeeze machine

It combines in single machine the operating principles of the jolt and squeeze machines. Combination of jolting and squeezing produces beneficial compaction effects on sand density and thus a more uniform hardness throughout the mould is attained. A jolt-squeeze machine makes use of match plate moulding.

Sand slinger

The sand slinger consists of a base, a sand bin, a bucket elevator, a swinging or movable arm, a belt conveyor and the sand impeller. Prepared sand lying in the sand bin is picked up by the elevator buckets and is dropped on to the belt conveyor which takes the same to the impeller head.

Inside the impeller head, rapidly rotating cup shaped blade picks up the sand and throws it downward into the moulding box as a continuous stream of sand with machine gun rapidity and great force.

The sand is discharged into the moulding box at a rate of 300 to 2000kg/minute. This force is great enough to ram the mould satisfactorily.

In moulding boxes, sand is filled and rammed at the same time. The density of sand which is the result of sand’s inertia is uniform throughout the mould.

Sand Testing Methods - Sand Testing Equipment

Methods of Sand testing:

The moulding sand after it is prepared should be properly tested to see that require properties are achieved. Tests are conducted on a sample of the standard sand. The moulding sand should be prepared exactly as it is done in the shop on the standard equipment and then carefully enclosed in a container to safeguard its moisture content.

Sand tests indicate the moulding sand performance and help the foundry men in controlling the properties of moulding sands. Sand testing controls the moulding sand properties through the control of its composition.

The following are the various types of sand control tests:

1. Moisture content test

2. Clay content test

3. Grain fitness test

4. Permeability test

5. Strength test

6. Refractoriness test

7. Mould hardness test

Moisture content test:

Moisture is the property of the moulding sand it is defined as the amount of water present in the moulding sand. Low moisture content in the moulding sand does not develop strength properties. High moisture content decreases permeability.

Procedures are:

1. 20 to 50 gms of prepared sand is placed in the pan and is heated by an infrared heater bulb for 2 to 3 minutes.

2. The moisture in the moulding sand is thus evaporated.

3. Moulding sand is taken out of the pan and reweighed.

4. The percentage of moisture can be calculated from the difference in the weights, of the original moist and the consequently dried sand samples.

Percentage of moisture content = (W1-W2)/(W1) %

Where, W1-Weight of the sand before drying,

W2-Weight of the sand after drying.

Clay content test:

Clay influences strength, permeability and other moulding properties. It is responsible for bonding sand particles together.

Procedures are:

1. Small quantity of prepared moulding sand was dried

2. Separate 50 gms of dry moulding sand and transfer wash bottle.

3. Add 475cc of distilled water + 25cc of a 3% NaOH.

4. Agitate this mixture about 10 minutes with the help of sand stirrer.

5. Fill the wash bottle with water up to the marker.

6. After the sand etc., has settled for about 10 minutes, Siphon out the water from the wash bottle.

7. Dry the settled down sand.

8. The clay content can be determined from the difference in weights of the initial and final sand samples.

Percentage of clay content = (W1-W2)/(W1) * 100

Where, W1-Weight of the sand before drying,

W2-Weight of the sand after drying.

Grain fitness test:

The grain size, distribution, grain fitness are determined with the help of the fitness testing of moulding sands. The apparatus consists of a number of standard sieves mounted one above the other, on a power driven shaker.

The shaker vibrates the sieves and the sand placed on the top sieve gets screened and collects on different sieves depending upon the various sizes of grains present in the moulding sand.

The top sieve is coarsest and the bottom-most sieve is the finest of all the sieves. In between sieve are placed in order of fineness from top to bottom.

Procedures are:

1. Sample of dry sand (clay removed sand) placed in the upper sieve

2. Sand is vibrated for definite period

3. The amount of same retained on each sieve is weighted.

4. Percentage distribution of grain is computed.

Permeability test:

The quantity of air that will pass through a standard specimen of the sand at a particular pressure condition is called the permeability of the sand.

Following are the major parts of the permeability test equipment:

1. An inverted bell jar, which floats in a water.

2. Specimen tube, for the purpose of hold the equipment

3. A manometer (measure the air pressure)

Steps involved are:

1. The air (2000cc volume) held in the bell jar is forced to pass through the sand specimen.

2. At this time air entering the specimen equal to the air escaped through the specimen

3. Take the pressure reading in the manometer.

4. Note the time required for 2000cc of air to pass the sand

5. Calculate the permeability number

6. Permeability number (N) = ((V x H) / (A x P x T))

Where,

V-Volume of air (cc)

H-Height of the specimen (mm)

A-Area of the specimen (mm²)

P-Air pressure (gm / cm²)

T-Time taken by the air to pass through the sand (seconds)

Strength test:

Measurements of strength of moulding sands can be carried out on the universal sand strength testing machine. The strength can be measured in compression, shear and tension.

The sands that could be tested are green sand, dry sand or core sand. The compression and shear test involve the standard cylindrical specimen that was used for the permeability test.

a. Green compression strength:

Green compression strength or simply green strength generally refers to the stress required to rupture the sand specimen under compressive loading. The sand specimen is taken out of the specimen tube and is immediately (any delay causes the drying of the sample which increases the strength) put on the strength testing machine and the force required to cause the compression failure is determined. The green strength of sands is generally in the range of 30 to 160 KPa.

b. Green shear strength:

With a sand sample similar to the above test, a different adapter is fitted in the universal machine so that the loading now be made for the shearing of the sand sample. The stress required to shear the specimen along the axis is then represented as the green shear strength. It may vary from 10 to 50 KPa.

c. Dry strength:

This test uses the standard specimens dried between 105 and 1100 C for 2 hours. Since the strength increases with drying, it may be necessary to apply larger stresses than the previous tests. The range of dry compression strengths found in moulding sands is from 140 to 1800 KPa, depending on the sand sample.

Steps involved are:

1. Specimen is held between the grips

2. Apply the hydraulic pressure by rotating the hand wheel

3. Taking the deformation use of the indicators.

Refractoriness test:

The refractoriness is used to measure the ability of the sand to withstand the higher temperature.

Steps involved are:

1. Prepare a cylindrical specimen of sand

2. Heating the specimen at 1500 C for 2 hours

3. Observe the changes in dimension and appearance

4. If the sand is good, it retains specimen share and shows very little expansion. If the sand is poor, specimen will shrink and distort.

Mould hardness test:

Hardness of the mould surface can be tested with the help of an “indentation hardness tester”. It consists of indicator, spring loaded spherical indenter.

The spherical indenter is penetrates into the mould surface at the time of testing. The depth of penetration w.r.t. the flat reference surface of the tester.

Mould hardness number = ((P) / (D – (D²-d²))

Where,

P- Applied Force (N)

D- Diameter of the indenter (mm)

d- Diameter of the indentation (mm)

Mechanical Testing of Materials

Various tests:

• Tensile Test

A tensile test, also known as a tension test, tests a material’s strength. It’s a mechanical test where a pulling force is applied to a material from both sides until the sample changes its shape or breaks. It’s is a common and important test that provides a variety of information about the material being tested, including the elongation, yield point, tensile strength, and ultimate strength of the material. Tensile tests are commonly performed on substances such as metals, plastics, wood, and ceramics.

Tensile testing systems use a number of different units of measurement. The International System of Units, or SI, recommends the use of either Pascals (Pa) or Newtons per square meter (N/m²) for describing tensile strength. In the United States, many engineers measure tensile strength in kilo-pound per square inch (KSI).

• Tensile test with electronic extensometer

This instrument is to be used on Tensile or Universal testing machines to find out Proof stress & Young’s modulus values. In case of many brittle materials such as high carbon steels, alloy steels, light aluminium & magnesium alloys, it is difficult to get yield values. For such materials stress corresponding to a certain allowable amount of plastic deformation is termed as proof stress say 0.1% or 0.2% proof stress. The measuring range is up to 5mm & resolution is 0.001mm.

• Tensile testing at elevated temperature.

High temperature tensile testing is a procedure to test the properties of a material at above room temperature. It will determine the following parameters:

• Tensile strength (breaking strength)
• Yield strength
• Elongation
• Reduction of area

Specialist testing, measurement and control equipment is required to perform this test.
The results of such a test will provide a good indication of the static load bearing capacity of the material and therefore establishes the suitability of a material for its intended purpose.

• Tensile test on Tor steel Bars

TOR steel is one of the best grade of steel used in concrete reinforced. It’s a kind of high adherence steel. Other types of steel are used for less resistance concrete. Thermo mechanically Treated (TMT) bars are a type of corrosion resistant steel reinforcing bar used in concrete construction.

• Bend test on plates

A bend test is used to determine whether a specific piece of metal in question will break or fracture under pressure. This is important in the construction of any project using metal, otherwise the building or the item being made could collapse from the immense pressure exerted on it. Every piece of metal made cannot be tested, therefore certain pieces are tested and if they pass, the other pieces are made using the same process. The results of a bend test are reported differently depending on the type of material tested. There is no standard method for reporting the durability that applies to all materials, rather each group has its own set by which it is judged and compared to other metals in that group.

The bend test is essentially measuring a metal’s ductility. Ductility defines how easily a metal can bend without breaking. The higher the ductility of a metal, the more it can bend without breaking or becoming deformed from its original shape. This is important because certain metals must handle pressure without snapping yet still be ductile enough to bend slightly and not lose their support or shape. Copper and steel are two metals that have a high ductility and do well under pressure.

• Bend test on pipes

Bending tests are carried out to ensure that a metal has sufficient ductility to stand bending without fracturing. A standard specimen is bent through a specified arc and in the case of strip, the direction of grain flow is noted and whether the bend is with or across the grain.

• Bend Test on Tor steel

The purpose is to make certain the weld and the base metal are properly fused, and that the weld metal and the heat affected zone (HAZ) have appropriate mechanical properties

• Re-Bend test on Tor steel

The purpose of re-bend test is to measure the effect of strain ageing on steel. Strain ageing has embrittlement effect which takes place after cold deformation by diffusion of nitrogen in steel. Hence, there is limitation stated in some design codes to restrict the nitrogen content of steel to 0.012%.

• Nick Break Test

The NICK-BREAK TEST is useful for determining the internal quality of the weld metal. This test reveals various internal defects (if present), such as slag inclusions,  gas  pockets,  lack of  fusion,  and  oxidized  or burned metal. To accomplish the nick-break test for checking a butt weld, you must first flame-cut the test specimens from a sample weld

FAILURE ANALYSIS

• Why ?

As the standards of our industry rise due to increasing globalization and competition, there is an ever growing need for consistency and reliability. Breakdown of any unit, system or equipment is an avoidable and costly occurrence and must be prevented or minimized. Analysis of such failures becomes a resourceful and affordable tool in addressing such unwanted occurrences.

To establish whether the cause of component failure lay on:

a) Service conditions
b) Design considerations
c) Material and its specification
d) Improper processing and assembly procedures or
e)  Combinations of these.

Only the real “Root cause” can ensure the effectiveness of corrective and preventive actions and avoid recurrence of failure.

• Stages Of Failure Analysis

1. Understanding and assimilation of background data and selection of samples.
2. Examination and documentation of the failed part by the following

1. Visual examination of parts, location (if necessary) and relevant photographs as well.

2.  Non destructive testing by means of Radiography, Dye      penetrant, Magnetic particle testing etc.

3. Mechanical Testing for various physical properties.

3. Vital specimens are selected, classified, and subjected to:

1. Macroscopic examination and analysis. This involves examining the fracture surfaces, secondary cracks, deposits and other such elements
2. Microscopic examination and analysis of fracture surface (by Scanning Electron Microscopy, if required).

4. Chemical analysis of material for conformation to specifications.

5. Chemical analysis of corrosion products, deposits, contaminants etc.

6. The actual state of the failed part and the failure mode are established.

7.  Fracture mechanics study if found necessary.

8. A simulation of the identical working environment to determine if any external      factors have contributed to the failure

9. Conclusions are determined after compiling all evidences and analysis and       then the report is generated.
10. Follow-up recommendations are also provided.

X-Ray Diffraction - Crystal Structure

It’s useful for studying Crystal structure

This method have the details about

• Grain size (or) Crystal size
• Orientation of the crystal
• Cold worked, Distorted and Internally stressed crystals
• Re-Crystallization
• Preferred orientation etc

Methods of Examining and Measuring the condition of Crystal Structure

1. The Laue back reflection method
2. The Rotating Crystal method
3. The DeBye- Scherrer (or) Powder method:

The Laue back Reflection method:
It’s applicable to single crystals (or) poly-Crystalline masses.
When a beam of Mono chromatic (i.e. of Single Wavelength) X-Ray is directed as a narrow pencil at a specimen of a metal diffraction takes place at certain of the crystallographic planes.
 

       

The Rotating Crystal method:
It’s a useful method for determining angles and positions of planes.
Crystallographic planes are brought in to reflecting positions by rotating a crystal (Specimen) about one of it’s axis while simultaneously radially it with a beam of mono chromatic x-Rays.
If crystal orientation planes are known, the angles and directions can be calculated.


The DeBye- Scherrer (or) Powder method:
The narrow pencil of monochromatic X-Rays is diffracted from the powder and recorded by the photographic film as a series of lines of varying armature.
By the Bragg Equation:

nλ=2d Sinθ

Where,

λ– Wave length of X-ray

d- Spacing of the atomic planes

θ – Angle of reflection