Design of a Special Purpose Dish Washing Machine

Abstract

This work is based on the design of a special purpose dish washing machine. Its special purpose lies in the fact that it handles only dishes made of ceramics. The machine is designed to use electrical energy for heating water and to produce rotation of the spray arm which project hot water unto the dishes. The principle on which the dish washing machine is designed is based on the fact that the pressure and water temperature of water jets required to produce scouring and softening effect on dirt and easily remove them is about 300kPa and 45^oC respectively. The force of the water jet impacting unto the dishes is taken into account in the design and the pressure due to the force exerted by the water jet produced, is negligible compared to both the tensile strength (1138 MPa) and compressive strength (2400 MPa) of the ceramic (Alumina Porcelain) or any other ceramic, and hence cannot break any of the ceramic dishes. The machine is designed to be fitted with a water heater, electric motor and a water pump of power rating 2.2KW, 0.25KW and 0.5KW respectively. The fabricated design of this special purpose dish washing machine will handle 20 dishes in a batch process and complete a wash cycle in a minimum of seven (7) minutes.