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Introduction To Machine Design
Machine Design is defined as the creation of new design or improving the exist one.
Machine is a combination of various elements arranged to work together to serve specific purpose.
Machine design includes designing the elements and arranging the elements optimally to serve the need.
1. Type of load and stresses caused by the load:
The load or force – internal stresses are set up
2. Motion of the parts: Depending upon the given specification the suitable prescribed motion of the part is to be evaluated. The motion of the parts are
(1) Rectilinear motion.(reciprocating)
(2) Curvilinear motion. (rotary)
(3) Constant speed.
(4) Constant or variable acceleration
3. Selection of materials
4. Form and size of the parts
5. Lubrication
6. Operational features
7. Use of standard parts
8. Safety of operation
9. Work shop facilities
10. Number of components to be manufactured
11. Cost of construction
12. Assembling
Material Selection
Selection of proper material for the machine components is one of the most important steps in process of machine design
The best material is one which will serve the desired purpose at minimum costs
Factors Considered while selecting the material:
Availability: Material should be readily available in market in large enough quantities to meet the requirement
Mechanical Properties of Material
Strength: Ability of the material to resist, without rupture, external forces causing various types of stresses
Elasticity: Ability to regain its original shape & size after deformation, when the external forces are removed
Plasticity: Ability to retain the deformation produced under the load on a permanent basis
Stiffness or Rigidity: Ability to resist deformation under the action of an external load
Mechanical Properties of Material
Toughness: Ability to absorb energy before fracture takes place
Malleability: Ability to deform to a greater extent before the sign of crack, when it is subjected to compressive force
Ductility: Ability to deform to a greater extent before the sign of crack, when subjected to tensile force
Brittleness: Property of the material which shows negligible plastic deformation fracture takes place
Hardness: Resistance to penetration or permanent deformation