Fabrication Of Yam Pounding Machine

3.2.6 SHAFT DESIGN
In this design, the important factor is to determine the minimum shaft diameter, which will be able to withstand the loads it will be subjected to. These loads include; the bending load, the torsion load and the axial pulley weight. Hence, the minimum shaft diameter can be determined using the expression.

Where
d     =     Minimum diameter of shaft
Mb    =    Maximum bending stress
Mt     =    Maximum bending stress
Kb     =    Fatigue factor for bending moment
Kt     =    Fatigue factor for torsional moment
But for the torsional torque Mt
    Mt = (Ta – Tb) Rb
Where
Ta    =    201.87N
Tb     =    66.18N
Rb    =    Radius of the beater pulley = 112mm = 0.112m


Then,
Mt  = (201.78 – 66.18) 0.112
    = 15.20Nm
    = 15.20 x 103Nmm
3.3    MATERIAL SELECTION
Material selection is one of the most important aspects that demand the understanding of each of the functional requirements. Especially for the individual machine components as they are ever-increasing varieties of materials presently available and the development of new material selection with unique properties and applications. Hence, the difficulty in materials is as a result of these varieties of materials in the engineering field coupled with the complex relationships between the selection parameters such as its functionality. If the selection process is done haphazardly, the risk of overlooking a possible attractive alternate material may occur.
To avoid this, there is the need for the analysis of the material performance requirement.
However, the material performance requirement was considered in the following areas:
3.3.1 BEARING DESIGN AND SELECTION
The single row deep groove ball bearing was chosen because of its high load carrying capacity and suitability for high running speed. Considering the diameter of the shaft which is 30mm, a bearing of bore 30mm was then used for this calculation.