LATEST UPDATES

Saturday, 30 June 2018

SHAFT ALIGNMENT - ALIGNMENT PLANES

Before we start learning alignment this is very important to know the types of misalignment planes and types of misalignment.
Generally there are two misalignment planes that we have to correct: 
          1) Vertical and 
          2) Horizontal.
In general there are two types of misalignment.
          1) Parallel (also known as Offset)
          2) Angular (also known as Gap).
Therefore, in the case of making a machine-train by using at least two machines, four types of misalignment can occur: 
          a) Vertical Offset
          b) Vertical Angularity
          c) Horizontal Offset, and
          d) Horizontal Angularity.
These can occur in any combination and in many cases, all four are present.

Vertical:
          Vertical misalignment means that the misalignment of the shafts in the vertical plane. In vertical misalignment both angular and offset misalignment can occur.
          Offset (Parallel) vertical misalignment happens when the motor shafts is moved vertically away from the pump shaft, but both shafts still operate in the same vertical plane and parallel.
          Gap (Angular) vertical misalignment occurs when the motor shaft is at an angle with the pump shaft, However, both shafts still operate within the same vertical plane.
          Vertical misalignment, which is corrected by the employment of Shims.

Horizontal:
          Horizontal misalignment means that the misalignment of the shaft in the horizontal plane. Just like vertical misalignment, in horizontal misalignment also both angular and offset misalignment can occur.
          Offset (Parallel) horizontal misalignment happens when the motor shaft is moved horizontally away from the pump shaft, but both shafts still operate in the same horizontal plane and parallel.
          Gap (Anhular) horizontal misalignment occurs when the motor shaft is at an angle with the pump shaft. However both shafts operate within the same horizontal plane. 
          Horizontal misalignment, which is not corrected by employing Shims. This type of misalignment is corrected by physically moving the MTBM.

Alignment Tolerances:

SHAFT ALIGNMENT -- FUNDAMENTALS

          In this article we are going to discuss the basic fundamentals of machine alignment. This section addresses precisely what alignment is and also what are the tools required to perform it, why it is required, how often it should be done and what steps should be taken prior to performing the alignment process.
          When the maing shafts are colinear at the coupling point they are considered to be in alignment. Here the term colinear refers to the condition when the two rotating mating shaft's centerlines are parallel and intersect (i.e., join to form as a single line). When this is often the case the coupled shafts operate just like a solid shaft. Any slight deviation from the aligned or colinear condition. However, ends-up in abnormal sound, vibration and wear of machine elements such as bearing and shaft seals.
          Variations in machine-component configuration and thermal growth will cause mounting-foot elevations and the horizontal orientation of individual drive-train components to be in different planes. However, they are considered to be properly aligned as long as their shafts are colinear at the coupling point.

Tools we use:
          Generally we use Dial gauge, Taper gauges, Feeler gauges and Outside micrometer calipers in the alignment procedure.

WHY WE HAVE TO PERFORM ALIGNMENT AND HOW OFTEN?
          Vibration effects of misalignment can seriously damage a piece of equipment. Slight misalignment is also cause vibration, this vibration reduces equipment life. Periodically checking of all coupled equipment alignment is one of the best 'tool' in Preventive Maintenance.
          Although during installation and also in previous check the machine is properly aligned, misalignment may develop in short interval of time. There are many causes for misalignment they are thermal expansion, distortion of attached equipment, foundation movement or settling etc.,

By the below indications we can sense the misalignment of machine:
1) More vibration in both vertical and axial directions
2) Shaft wobling
3) Bearing temperature
4) Noise (From coupling and from bearing housing)
5) Coupling wear (In Lovejoy RNS coupling rubbers damage, In tyre coupling - coupling tyre wear).

ACTIONS TO BE TAKEN BEFORE ALIGNMENT:
          The alignment procedure is crucial so we have to be performed correctly. Using correct sequence is one of the most important factor in shaft alignment process. Understanding and using the correct actions will decrease the shaft alignment time and improve efficiency. In this article we are suggesting some actions to be taken before alignment, which cover the preparatory steps as well as two major issues (i.e., Soft-foot and Indicator sag corrections) that must be resolved before alignment can be accomplished. This section provides policies for making the right path to capture these corrections as well as the correct way to tighten hold-down nuts, an important process that is needed when the correcting soft-foot.
Image credits : Youtube --The Real Female Entrepreneur

Preparatory Steps :
          The following preparation actions should be taken before attempting to allign a machine train:

1) The base of machine and the base where we kept machine is to be cleaned with a wire brush or a file, to make sure it is clean, burr free and rust free.
2) Prior to adjusting the driver unit align with drive unit, driven unit is to be placed to the required level, position, and secure. Keep the shaft centre line of the driven unit slightly more than the driver.
3) Make sure that the shims that we are using do not have any burrs and not been "kinked".
4) Make sure the shaft doesnot have an indicated runout.
5) Before starting the alignment procedure check for "soft-foot", and correct it.
6) Always tight the hold-down nuts in the correct tightening sequence.
7) Determine the amount of indicator sag before starting the alignment policy.
8) To avoid the lifting of the machinery more than that we need, add or remove shims.
9) Jacking bolt assemblies should be welded onto the bases of all large machinery. If they are not provided, add them before starting the alignment procedure. Use jacking bolts to adjust for horizontzl offset and angular misalignment and to hold the machine in place while shimming.

Thursday, 14 June 2018

SHAFT ALIGNMENT

          Shaft alignment is process of positioning (or) aligning of shaft center lines of the driven and driver components (i.e., gearboxes, pumps, rolls etc.,) within a tolerated margin. Alignment is accomplished by giving shimming or moving machine components or sometimes both. The aim of shaft alignment is to maintain a common axis of rotation at operating equilibrium for two coupled shafts.
          In case of high speed equipment if the shaft alignment is not perfect we cant get maximum reliability and life through that equipment. Alignment is important in the case of direct coupled shafts and also the shafts of machines that are separated by distance even though we use flexible coupling. Shaft alignment is very important why because due to misalignment a lot of stress on shafts, vibration and noise produces. This causes excessive wear, bearing problems like heating and bearing failure, and results in the need for frequent repairs. By proper alignment we can reduce noise, vibration and also power consumption and this helps to achieve the design life of bearing, seal, shaft and coupling. 


          Alignment procedure is done by assuming a machine component is stationary, level and supported properly its base plate and foundation. Both angular and offset alignment must be performed in the vertical and horizontal planes, which is obtained by moving horizontally or by raising or lowering to align with the rotational center line of the stationary shaft. The movable components are designed as Machines To Be Moved (MTBM) or Machines To Be Shimmed (MTBS). MTBM generally refers to correction in horizontal planes and MTBS refers to corrections in vertical planes. 

Thursday, 7 June 2018

Phenomenon of Light

Phenomenon of Light:
Phenomenon
Visible Effect
Refraction of light
Day is lengthened (4 min due to atmosphere refraction)
Stars appear to twinkle
Mirages are formed
Sun or moon appears larger in size when at horizon
Pencil in the beaker appear broken
Stick immersed in water appears bent at the point of separation
A person standing inside water appears shorter
Writing on a paper appear lifted when glass slab is placed over the paper.
Dispersion of light
Deviation of light passes through a prism
Rainbows are formed
Interference of light
Beautiful colours are seen in soap bubbles and oil films on water
Scattering of light rays of small wavelengths
Sky appears blue
Clouds appear white
Sun appears red during sunrise and sunset
Total internal Reflection
For mation of mirages in desert
Air bubbles in glass paper weight appear silvery white
Sparkling of diamond 


Facts to Remember:

Facts to Remember
The speed of light
186,000 miles per second (or)  3X 108 m/s
Colour of light with smallest wavelength
Violet
Colour of light with longest wavelength
Red
Colour which scatterd most and which scatter least
Most - Violet
Least- Red
Colour which deviates more and which deviates less
Most - Violet
Least - Red
Three dimensional imaging using interference of light is known as
Holography
System of light excitation used in surgeries, printers etc
LASER
The colour of light which is most conducive to photosynthesis
Blue
The study of properties and behaviour of light is known as
Optics

Friday, 1 June 2018

Chemistry Notes: Some important metals and their Uses

Dear Readers,
Here we will discuss metals and their uses.

Metals:
1. Metals are good conductors of heat, sound & electricity and are malleable and ductile.
2. When compared to all metals Gold and silver are most malleable and best ductile metals.
3. Silver is the best conductor of heat followed by copper.
4. Cooking utensils are made of Aluminium and copper because they are good conductors of heat.
5. Mercury is liquid at room temperaure.
6. Mercury offers high resistance to the flow of electric current.
7. Sodium and potassium are so soft that they can be easily cut with knife.
8. Metals are electropositive in nature.
9. Almost all the metal oxide are basic in nature but zinc oxide and aluminium oxide are amphoteric.



Alkali metals and their properties:
a. Lithium, sodium, potassium, rubidium and cesium are alkali metals.
b. These metals react with air so they are stored under kerosene or liquid paraffin.

Sodium chloride (NaCl):
--> It is generally called as common salt or table salt.
--> They are white crystals which do not have smell or odor but possess taste.
--> Used in the industrial manufacturing of sodium hydroxide and chlorine gas.
--> It is used as a starting material in the manufacturing of caustic soda.
--> In cold countries it is used in the removing of ice from road, now a days CaCl2 and MgCl2 are also used for this purpose.

Sodium hydroxide (NaOH):
A. Used in the refining of bauxite material.
B. It is major ingradient in drain cleaners.
C. Used in soap, dyes and artificial industries.

Backing Soda or Sodium bicarbonate (NaHCO3):
1. It is commonly known as baking soda.
2. When mixed with a mild edible acid such as Tartaric acid, it is called as ‘Backing Powder’.
3. Used as a mild antiseptic for skin infections.
4. Used for wool washing.
5. Used in the fire extinguisher.
6. Ant and Bee sting contains Methonoic (or) Formic acid, due to which victim feel pain and irritation on bite. Baking soda is used a remedy for it.

Washing Soda or Sodium carbonate (Na2CO3):
a. It is generally known as washing soda.
b. Used for removing permanent hardness of water.
c. Mixture of sodium carbonate and potassium carbonate is known as Fusion mixture.

Sodium Sulphate (Na2SO4):
1. It is commonly known as Glauber’s salt.
2. It is also called as Sulfate of soda. 
3. It is used as purgative.
4. It is used as drying agent.

Sodium thiosulphate (Na2S2O3):
--> It is commonly known as Hypo.
--> Used in the photography as fixing agent.
--> It is used as a antidote for treating cyanide poisoning.
--> Used in Leather tanning, and gold extraction.

Potassium carbonate (K2CO3):
A. It is known as pearl ash.
B. It is also used in fire extinguishers, soap making.
C. We can found it in Effervescent tablets, these tablets are used to provide potassium when there is low levels of potassium in blood.

Potassium hydroxide (KOH):
a. Commonly known as caustic potash.
b. Use in the preparation of soft soap by saponification.
c. Used as a electrolite in alkaline batteries.
d. Its aqueous solution is known as potash Iye.
e. It is also used in petrolium refining, Fertilizer production and Cleaning solutions.

Potassium superoxide (KO2):
Used in space capsules, submarines and breathing mask because it liberates Oxygen and removes carbon dioxide and carbon monoixide.

@2017 All Rights Reserved. Designed by WWW.SMARTWAY4STUDY.COM !!!! Sitemap !!!! Blogger Templates