Soybean Grinding Machine for Automatic Purpose by PLC Application

Abstract

This project aimed to develop soybean grinding process. An ordinary manual grinding machine was modified to be working automatically. An ordinary soybean grinding machine needed an operator to operate it almost every process.Automatic processes such as soybean weight controlling, soaking water supply and soybean soaking time, grinding water supply, grinding controlling and rinsing water supply for grinding unit were applied for automatic purpose. This unit would control raw soybean to mixing water ratio at desired value to be around 1.0 kg: 5.0 kg in order to maintain the quality of the product. The weight of raw soybean and grinded soybean was monitored to find that ratio to prove reliability of automatic system. Soybean grinding machine had a 1 phase, 0 . 5 HP. motor as primary driving component. The driving wheel belt ratio was 1 : 1 to drive a 1 5 0 mm. grinding unit. Electric water pump and water tank were used for supplying water to during all process. Three solenoid valves were used to control supply water. An automatic process was archived by using Programmable Logic Controller (PLC). The process started from loading soybean until getting raw soy milk at the end of the process. The testing result when this unit to grind soybean in the amount of 1.0 to 5.0 kg. with 0.5 kg. increment showed that the grinding rate was around 7.14 kg. of raw soybean an hour with error around 0.7% and standard deviation of 0.004 kg. of grinded soybean.The grinded soybean have average raw soybean to mixing water ratio of about 1 : 5 . 0 4 which was appropriate for consumption. To operate this automatically grinding machine in full capacity, 6 working hours per day, would get the breakeven point in 457 days.