Abstract
Several efforts have been made to mitigate cutting tool vibration in one of the modern mainstays of manufacturing and production nowadays, which is computer numerical control (CNC). Vibrations in the CNC milling process are often created by a variety of factors and some of them are often difficult to prevent since a good quality CNC machine can be extremely expensive. Important factors that aid in the reduction of amplitude of vibrations in a CNC machine include the quality of the bearings and various mating parts; parts that make the structural integrity of CNC machines more rigid. In the year 2016, a group of undergraduate mechanical engineering students from the California State University, Sacramento designed a CNC machine using a 120V router, T-slotted aluminum extrusions, a CNC router table, and a computer in order to program output. A factorial design of three factors was considered and it was cutting speed, feed rate, and depth of cut. Before stiffening up the CNC machine, the cutting tool speed desired to create a decent surface finish was from 10 to 60 inches per minute (IPM). The result of increasing speed produced large amounts of vibration that lead to lower quality surface finish and dimensional accuracy of finished products. In order to achieve optimum cut, speed and feed rate need to match theoretically. The study will be addressed by stiffening the tool holding structure on the CNC machine by increasing the moment of inertia in the back of the T-slotted aluminum extrusions that hold the router in place. This will stiffen the T-slotted extrusion tool support structure and will give better tolerances, better surface finish, and a better tool and machine life. An increased moment of inertia produced will enable higher speeds.
Results revealed that vibrations directly influence surface finish, feed rate, and depth of cut in this case. At the end, machining effects on the surface finish of materials were analyzed and discussed.