Effects of design parameters on dimensional accuracy of parts made on a mini 3-axis CNC router

Abstract

Computer numerical control (CNC) is a very broad term that encompasses a variety of types of machines used in industrial automation — all with different sizes, shapes, and functions. But the easiest way to think about CNC is to simply understand that it is all about using a computer as a means to control a machine that carves useful objects from solid blocks of material. Traditional CNC machines are expensive, complicated, and typically only found in large manufacturing companies that can afford them. Small hobbyist CNC machines can run anywhere from $7,000 and higher; professional machines can cost millions of dollars! Now, for a fraction of the cost — under $800 one can own a Mini 3-axis CNC machine and cut, drill, mill, and carve objects of one's imagination. In this paper, a Mini 3-axis CNC router was assembled and tested for machining different materials such as plastic and wood. Simple shapes of circles (diameter, d = 1") and squares (side, a = 1") were cut using the CNC router. G-Code programs were developed to cut the required circles and squares. A digital caliper was used to measure the diameter of the circles and the side of the squares. Data were collected for a 2k factorial design experiments considering 2-levels for parameters: spindle speed, feed rate, cut depth, object shape, and material. Statistical analyses were performed to determine the effects of chosen parameters on the dimensional accuracy of the parts made. The results indicated that the parameters material, object shape, and cut depth have significant effects on the dimensional accuracy of the parts made.