Donut Making Machine Controlled by Electro-pneumatic System

Abstract

This research project presents to aim at building the prototype of a donut making machine which is a convenience machine in working fast and can make donuts a lot and reduce in feeling stiff. The donut making machine has characteristic operation in frying a donut milled wheat flour. The starting in producing donut is to take liquid condition and fine wheat flour be contained in donut cylinder. And then, the mechanism of pneumatic system that is piston rod of pneumatic cylinder pushed flour in liquid and fine condition into hot oil pan, suitable oil temperature. The operation of pneumatic system is controlled by electrical system and electro-pneumatic system. It can be adjust the size of each donut in almost the same size which happen by adjusted range in motion of piston rod of pneumatic cylinder that can control the reed switch contacted with cylinder to slide up and down along the side of cylinder. The test result revealed that the donut making machine could make 20 ripe donuts per minute at the temperature of vegetable oil at 180 degree Celsius. The ripe donuts leave little oil and the outside diameter at 60.1 millemeters and weight at 19.9 grams in average. The four main factors depending OR sizing of donut are as follows. 1. The range of movement of piston rod of pneumatic cylinder was adjusted by reed switch. 2. The liquid wheat flour is sticky. 3. The changing of sticky donut liquid flour is affected because of heat transfer at range of height from level of hot oil to the bottom of donut cylinder. And 4. the changing of sticky donut liquid flour is affected because of weather condition.