Fabrication Of Yam Pounding Machine

4.1.3 THE FRAME
The frame was considered one of the major component of the machine. It was made of mild steel and welded to remain one of the most versatile and effective means of fabrication and individual component assembly into larger module.
Mild steel is a type of steel in which carbon is the primary alloying element, with the level of carbon contained in a steel being one of the most important factor governing it’s mechanical properties. Mild steel is available with varying levels of formability.
Therefore, it gives the machine high strength to withstand the movement of the shaft and it makes the machine lost for a long period of time.
4.1.4 THE SHAFT
The shaft was made with High Speed Steel (HSS). It is distinct from High Carbon Steel (HCS), since it features a high wear resistance. It possesses red hardness, i.e. retain its properties at the red-heat temperature (500oC-600oC). it permit a nearly 100% increase in crushing speed and gave rise to the name High Speed Steel (HSS).
Therefore, it gives the machine high pounding strength without depreciation in rate for a very long time. It also gives rise to the prolonged life of the machine for about 7 to 10 years.
4.1.5 THE SITTING
Every mechanical or electrical operating machine is subjected to vibration due to the moving parts of the machine. More often, vibration is undesirable, wasting energy and creating unwanted sound. To reduce or minimize vibration, dampers are put in place to receive the vibrations.
However, dampers are placed in the sitting of this machine to reduce the vibration caused by the rotating parts of the machine.
4.1.6 ASSEMBLY
The frame of the machine made of mild steel was welded which remain one of the most versatile and effective means of fabrication and individual components assembly into larger module. Hence, it is a fabrication process that joins materials such as metals, thermoplastics by way of causing coalescence (which is often done by melting the work piece and a filler material to form a pool of molten metal (the welded puddle) that cools to become strong joint with pressure sometimes used in conjunction with heat or by itself produces the weld. This was done by electrical arc welding and the electrode.
This welded steel forms the rectangular frame for coupling the other parts of the machine such as the prime mover and the trough for pounding.
Also, other modes of assembling used here were riveting and screws which were fastened to the hold, the 2mm thin sheet.
However, the entire structure was filed and polished with abrasive paper to obtain a perfect finish and was painted with spraying machine and was then allowed to dry in a dust free environment.
4.1.7 MODE OF OPERATION
In this design, the action of pounding is done by the machine. The boiled yam is put into the machine and covered. The prime mover is switched on to initiate a crushing and kneading action inside the machine by virtue of crushing and kneading beater (Blade). This continues until the yam has attained the desired texture needed. Damping of the drought is made possible by continuous flow of steam into the mortar.
4.2    TESTING AND EVALUATION OF EFFICIENCY
After the design of this machine, some experiments, survey and study were carried out to generate feasible and best values for the design.
4.2.1 RESULT AND DISCUSSION
Three species of cooked yams where tested with the machine by operating it to pound the cooked yams and it was observed that the white yam (Dioscorea rotundata), took a maximum time of two minutes thirty seconds, the yellow yam (Dioscorea cayenensis), took a maximum time of three minutes and the water yam (Dioscorea alata) took a maximum time of two minutes. However, only the water yam was semi-starchy while the white and yellow yam were starch.
The machine was also observed while in operation and it was found that the resistance of the prime mover to vibrations and its performance were satisfactory, pointing to the fact that a greater percentage of the vibrations set up during the pounding process are absorbed by the damper on the machine sitting and fan belt.