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Shaft & keys (machine design & industrial drafting )

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Digvijaysinh Gohil

This document discusses different types of shafts, keys, and their design considerations. It contains the following key points: 1. Shafts can be classified based on their shape (solid or hollow), application (transmitting, machine, spindle), and construction (rigid or flexible). 2. Keys are used to connect rotating machine elements to shafts and prevent relative motion. Common types include rectangular, square, parallel, gib-head, feather, and woodruff keys. 3. Shaft design considers factors like bending moment, shear stress, and material properties. Hollow shafts have higher strength-to-weight ratio than solid shafts of the same size.

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Subject :- MDID (2141907) Topic :- Shaft & Keys Guided By :- Mr. Rudraduttsinh Parmar (Assistant professor) Prepared By :- 150990119029 Keval Patel 150990119030 Krupal Patel 150990119031 Mayur Patel 150990119032 Meet Patel 150990119033 Parthiv Patel
Types of shaft • Hollow shape • Solid shaft Based On Shape
Transmitting Shafts  Line shaft :- It is use to transmit the power to several machine.  Stub shaft :- When shaft is an integral part of the machine or engine is called stub shaft.  Counter shaft :- A shaft that connect to prime mover to line of machine is called counter shaft. Based on Application
Machine Shaft :- When shaft is an integral part of the machine or engine is called machine shaft. Spindle shaft :- A short hollow shaft having application of transmitting the power to tool or a machine is called spindle shaft.
Based on Construction Rigid shaft :- It is a shaft which cannot be bend or deformed out of shape during transmission of rotary motion between two object or machine. Flexible shaft:- It is a shaft which is partially deformed in a manner not to affect the transmission of motion is known as flexible shaft.
Difference b/w shaft , spindle, axle Sr No. Shafts Spindle Axle 1 Shaft is a rotating member. Spindle is a rotating member. Axel is a non- rotating member 2 The purpose of shaft is to transmit the torque and to support the transmission elements . The spindle is a short rotating shaft which is an integral part of the machine. The purpose of an axel is only to support the transmitting elements . 3 Shaft is subjected to torque , bending moment or axial force Spindle is subjected to bending moment and / or axial force Axle is subjected to bending moment and / or axial force 4 Example :- Line shaft , counter shaft , spindle , crankshaft etc. Example :- Lathe machine spindle , drilling machine spindle, milling machine spindle etc. Example:- Front axle car , wheel axle of motorcycle etc.
Design of shaft based on bending moment for solid shaft so, And,
for hollow shaft M=bending moment I=moment of inertia =bending stress Y=
EXAMPLE:-Find the diameter of solid shaft to transmitte 25 kw at 225 r.p.m the allowable shear stress is equal to 50 mpa. If we used hollow shaft in case of solid shaft then find the inside & outside diameter of the shaft when the ratio of the inside to outside diameter is equal to 3:4. ANSWER:- Given data d=? P=25kw N=225 r.p.m τ=50 mpa
Shaft & keys (machine design & industrial drafting )
DESIGN OF SHAFT BASED ON ASME CODE In most of the case shafts are not under constant Torque & Bending.
Shaft & keys (machine design & industrial drafting )
Example .  A mild steel shaft transmits 20 kW at 200 rpm.  It carries a central load of 900N and is simply supported between the bearings 2.5 m apart.  Determine the size of the shaft,  If the allowable shear stress is 42 MPa and the maximum tensile or compressive stress is not to exceed 56 MPa.  What size of the shaft will be required,  if it is subjected to gradually applied loads. DATA: 13
 maximum bending moment of a simply supported shaft carrying a central load, Putting values in equation eq: 1 ………… EQ: 1 14
We know that the equivalent bending moment, ………… eq: 2 Putting values in equation eq: 2 Taking the larger of the two values, we have 15
2.Size of the shaft when subjected to gradually applied load Putting values of M, T, and other constants in above equation Putting value of Te in equation no 3 …………equation no 3 for rotating shafts with gradually applied loads 16
We know that the equivalent bending moment, Putting values in above equation eq Taking the larger of the two values, we have 17
Shafts Subjected to Combined Twisting Moment and Bending Moment When the shaft is subjected to combined twisting moment and bending moment, then the shaft must be designed on the basis of the two moments simultaneously. Various theories have been suggested to account for the elastic failure of the materials when they are subjected to various types of combined stresses. The following two theories are important from the subject point of view : 1. Maximum shear stress theory or Guest's theory. It is used for ductile materials such as mild steel. 2. Maximum normal stress theory or Rankine’s theory. It is used for brittle materials such as cast iron. Let τ = Shear stress induced due to twisting moment, and σb = Bending stress (tensile or compressive) induced due to bending moment. According to maximum shear stress theory, the maximum shear stress in the shaft,
Substituting the values of τ and σb from Art. 14.9 and Art. 14.10, we have
Shaft & keys (machine design & industrial drafting )
What is key ?????  A key is a machine element used to connect a rotating machine element to a shaft. It is always inserted parallel to the exist of the shaft. A keyway is a slot in a shaft and hub of the pulley to accommodate a key.
Types of Keys
Sunk key • The sunk key are provided half in the keyway of the shaft and half in the keyway of the hub . • The sunk key are of the following types: 1. Rectangular key 2. Square key 3. Parallel key 4. Gib-Head key 5. Feather key 6. Woodruff Key
Rectangular Key • A key is a piece of mild steel inserted between the shaft and hub of the pulley to connect these together in order to prevent relative motion between them. The key has taper 1 in 100 on the top side only.
Square Key • The only difference between a rectangular sunk key and a square sunk key is that its width and thickness are equal. i.e , W=t=d/4
Parallel key • The parallel sunk key may be of rectangular or square section uniform in width and thickness throughout. • It may be noted that a parallel key is a taperless and is used where the pulley, gear or other mating piece is required to solid along the shaft.
Gib-Head Key • It is a rectangular sunk key with a head at one end known as Gib-Head Key. • It is usually provided to facilitate and removal of key.
Feather key • A key attached to one member of a pair and which permits relative axial movement is known as feather key. • It is a special type of parallel key which transmits a turning movement and also permits axial movement.
Woodruff Key  The woodruff key is an easily adjustable key.  It is piece from a cylindrical disc having segmental cross-section in front view of figure.  This key is largely used in machine tool and automobile construction.
Hollow Saddle Key :-  A Hollow saddle key is a taper key which fits in a keyway in the hub and the bottom of the key is shaped to fit the curved surface of the shaft. •It is used as a temporary fastening in fixing and setting cams etc.
Tangent Keys  The tangent key are fitted in a pair at right angles.  Each key is to withatand torsion in one direction only.  sThey are used in large heavy duty shaft.
Round key  The round keys, are circular in section and fit into holes drilled partly in the shaft and partly in the hub.  They have advantage that their keyways may be drilled and reamed after the mating parts have been assembled.
Splines  Sometimes, keys are made integral with the shaft which fit in the keyways broached in the hub. Such shafts are known as splined shafts.  The Splined shaft are used when the forces to be transmitted is large in proportional to the size of the shaft.
Shaft & keys (machine design & industrial drafting )

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Shaft & keys (machine design & industrial drafting )

  • 1. Subject :- MDID (2141907) Topic :- Shaft & Keys Guided By :- Mr. Rudraduttsinh Parmar (Assistant professor) Prepared By :- 150990119029 Keval Patel 150990119030 Krupal Patel 150990119031 Mayur Patel 150990119032 Meet Patel 150990119033 Parthiv Patel
  • 2. Types of shaft • Hollow shape • Solid shaft Based On Shape
  • 3. Transmitting Shafts  Line shaft :- It is use to transmit the power to several machine.  Stub shaft :- When shaft is an integral part of the machine or engine is called stub shaft.  Counter shaft :- A shaft that connect to prime mover to line of machine is called counter shaft. Based on Application
  • 4. Machine Shaft :- When shaft is an integral part of the machine or engine is called machine shaft. Spindle shaft :- A short hollow shaft having application of transmitting the power to tool or a machine is called spindle shaft.
  • 5. Based on Construction Rigid shaft :- It is a shaft which cannot be bend or deformed out of shape during transmission of rotary motion between two object or machine. Flexible shaft:- It is a shaft which is partially deformed in a manner not to affect the transmission of motion is known as flexible shaft.
  • 6. Difference b/w shaft , spindle, axle Sr No. Shafts Spindle Axle 1 Shaft is a rotating member. Spindle is a rotating member. Axel is a non- rotating member 2 The purpose of shaft is to transmit the torque and to support the transmission elements . The spindle is a short rotating shaft which is an integral part of the machine. The purpose of an axel is only to support the transmitting elements . 3 Shaft is subjected to torque , bending moment or axial force Spindle is subjected to bending moment and / or axial force Axle is subjected to bending moment and / or axial force 4 Example :- Line shaft , counter shaft , spindle , crankshaft etc. Example :- Lathe machine spindle , drilling machine spindle, milling machine spindle etc. Example:- Front axle car , wheel axle of motorcycle etc.
  • 7. Design of shaft based on bending moment for solid shaft so, And,
  • 8. for hollow shaft M=bending moment I=moment of inertia =bending stress Y=
  • 9. EXAMPLE:-Find the diameter of solid shaft to transmitte 25 kw at 225 r.p.m the allowable shear stress is equal to 50 mpa. If we used hollow shaft in case of solid shaft then find the inside & outside diameter of the shaft when the ratio of the inside to outside diameter is equal to 3:4. ANSWER:- Given data d=? P=25kw N=225 r.p.m τ=50 mpa
  • 11. DESIGN OF SHAFT BASED ON ASME CODE In most of the case shafts are not under constant Torque & Bending.
  • 13. Example .  A mild steel shaft transmits 20 kW at 200 rpm.  It carries a central load of 900N and is simply supported between the bearings 2.5 m apart.  Determine the size of the shaft,  If the allowable shear stress is 42 MPa and the maximum tensile or compressive stress is not to exceed 56 MPa.  What size of the shaft will be required,  if it is subjected to gradually applied loads. DATA: 13
  • 14.  maximum bending moment of a simply supported shaft carrying a central load, Putting values in equation eq: 1 ………… EQ: 1 14
  • 15. We know that the equivalent bending moment, ………… eq: 2 Putting values in equation eq: 2 Taking the larger of the two values, we have 15
  • 16. 2.Size of the shaft when subjected to gradually applied load Putting values of M, T, and other constants in above equation Putting value of Te in equation no 3 …………equation no 3 for rotating shafts with gradually applied loads 16
  • 17. We know that the equivalent bending moment, Putting values in above equation eq Taking the larger of the two values, we have 17
  • 18. Shafts Subjected to Combined Twisting Moment and Bending Moment When the shaft is subjected to combined twisting moment and bending moment, then the shaft must be designed on the basis of the two moments simultaneously. Various theories have been suggested to account for the elastic failure of the materials when they are subjected to various types of combined stresses. The following two theories are important from the subject point of view : 1. Maximum shear stress theory or Guest's theory. It is used for ductile materials such as mild steel. 2. Maximum normal stress theory or Rankine’s theory. It is used for brittle materials such as cast iron. Let τ = Shear stress induced due to twisting moment, and σb = Bending stress (tensile or compressive) induced due to bending moment. According to maximum shear stress theory, the maximum shear stress in the shaft,
  • 19. Substituting the values of τ and σb from Art. 14.9 and Art. 14.10, we have
  • 21. What is key ?????  A key is a machine element used to connect a rotating machine element to a shaft. It is always inserted parallel to the exist of the shaft. A keyway is a slot in a shaft and hub of the pulley to accommodate a key.
  • 23. Sunk key • The sunk key are provided half in the keyway of the shaft and half in the keyway of the hub . • The sunk key are of the following types: 1. Rectangular key 2. Square key 3. Parallel key 4. Gib-Head key 5. Feather key 6. Woodruff Key
  • 24. Rectangular Key • A key is a piece of mild steel inserted between the shaft and hub of the pulley to connect these together in order to prevent relative motion between them. The key has taper 1 in 100 on the top side only.
  • 25. Square Key • The only difference between a rectangular sunk key and a square sunk key is that its width and thickness are equal. i.e , W=t=d/4
  • 26. Parallel key • The parallel sunk key may be of rectangular or square section uniform in width and thickness throughout. • It may be noted that a parallel key is a taperless and is used where the pulley, gear or other mating piece is required to solid along the shaft.
  • 27. Gib-Head Key • It is a rectangular sunk key with a head at one end known as Gib-Head Key. • It is usually provided to facilitate and removal of key.
  • 28. Feather key • A key attached to one member of a pair and which permits relative axial movement is known as feather key. • It is a special type of parallel key which transmits a turning movement and also permits axial movement.
  • 29. Woodruff Key  The woodruff key is an easily adjustable key.  It is piece from a cylindrical disc having segmental cross-section in front view of figure.  This key is largely used in machine tool and automobile construction.
  • 30. Hollow Saddle Key :-  A Hollow saddle key is a taper key which fits in a keyway in the hub and the bottom of the key is shaped to fit the curved surface of the shaft. •It is used as a temporary fastening in fixing and setting cams etc.
  • 31. Tangent Keys  The tangent key are fitted in a pair at right angles.  Each key is to withatand torsion in one direction only.  sThey are used in large heavy duty shaft.
  • 32. Round key  The round keys, are circular in section and fit into holes drilled partly in the shaft and partly in the hub.  They have advantage that their keyways may be drilled and reamed after the mating parts have been assembled.
  • 33. Splines  Sometimes, keys are made integral with the shaft which fit in the keyways broached in the hub. Such shafts are known as splined shafts.  The Splined shaft are used when the forces to be transmitted is large in proportional to the size of the shaft.