Design, development and performance evaluation of fruit and vegetable grader

Under competitive market conditions of today's agriculture fruit and vegetables quality is of great importance. Grading of agricultural produce especially the fruit and vegetables has become a prequisite of across the borders trade. In Pakistan grading is mainly done manually that requires significant labor work. Human operations may be inconsistent, less efficient and time consuming. New trends in marketing as specified by World Trade Organization (WTO) demand high quality graded products. Farmers are looking forward to have an appropriate agricultural produce-grading machine in order to alleviate the labor shortage, time saving and graded products quality improvement. Keeping in view the market requirements as desired by the WTO and quality conscious consumers, a spool type mobile grader machine was designed and developed, using locally available indigenous materials. Three functional units were fabricated: take-in conveyor, grading unit and take-away conveyor, all mounted on a main frame. For optimizing feed rate of the grader, three take-in conveyor speed 10, 15 and 20 m/min were selected to load the crop on the grading unit at 6, 9 and 12 t/hr respectively. A drive mechanism with three speed levels 25 50 and 75 rpm were developed to accommodate the different feed rates. To convey the graded produce to the packing point take-away conveyors were developed that operated at three speeds, 5, 10 and 15 m/min without causing the mutual collusion of the falling produce from grading unit. Increased grading speeds of about 75 rpm resulted in increased damage index whereas higher take-in conveyor speeds of about 20 m/min resulted in more grading errors. Effective human supervision was found important for ensuring smooth operation of the grader. The average grading charges were about Rs.4 /100 kg of produce.