01)Type of Load and Stresses caused by the Load:-
The load on the Machine Component,may act in several ways due to which the Internal Stresses are set up.
02)Motion of Parts:-
The successful operation of any Machine depends largely upon the simplest arrangements of the Parts,which will give the required motion.The Motion of the Part may be
A)Rectilinear Motion,which includes Unidirectional and Reciprocating Motion.
B)Curvilinear Motion,which includes Rotary,Oscillatory Simple Hormonic.
D)Constant or Variable Acceleration.
03)Selection of Material:-
Every Machine Design Engineer should have a thorough knowledge of the Properties of Material and their behaviour under working conditions.
04)Form and Size of the Parts:-
In order to design any Machine Part for form and size,it is necessary to know the Forces which the Part must sustain.Any suddenly applied or impact load must be taken into consideration,which may cause failure.The smallest Practicable Cross-Section may be used,but it may be checked that the Stresses induced in the Designed Cross-Section are reasonably safe.
05)Frictional Resistance and Lubrication:-
There is always a Loss of Power due to Frictional Resistance.Careful attention must be given to the matter of Lubrication of all surfaces which moves in contact with others.
06)Safety of Operator:-
A Machine Designer should always provide safety device for the safety of the operator.The Safety Appliances should in no way interfere with the operation of the Machine.
07)Use of Standard Parts:-
The use of Standard Parts are closely related to the Cost of Machine,because the Cost of Standard Parts is only a fraction of the cost of similar parts made to order.
08)Convenient and Economical Features:-
The operating feature of the Machine should be carefully studied.The Starting,Controlling and Stopping Levers should be located on the basis of convenient handling.
A Design Engineer should be familiar with limitation of his Employer's Workshop,in order to avoid the necessity of having work-done in some other Workshop.
Every Machine must be Assembled as a unit before it can function.The final Location of any Machine is important and the Design Engineer must anticipate the exact location and the local facilities for erection.
Above considerations are most important in machine design engineering.
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