A Study on Chattering in Edu-Lathe CNC Turning Machine

Chan, Eddie Chun Ti (2018) A Study on Chattering in Edu-Lathe CNC Turning Machine. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

The common problems faced in CNC lathe machine are chattering and surface roughness which these problems had related on each other. Chatter is the vibration that have a violent relative motion between the work-piece and cutting tool or it can be considered as a harmonic or resonant event which occurs during the vibration from the machine, cutting tool and work-piece. Surface roughness is the measure of the texture of a surface that had manufactured. If the surface is too rough, it will results in high surface roughness. In opposite, if the surface is smooth, it results in low surface roughness. These problems will actually harm the CNC lathe machine if these problems are not solve as soon as possible. If the CNC lathe machine is being harm, it will brings negative effects such as low productivity, inaccuracy of machining operation and other relevant effects. In this project, 3 parameters which are cutting depth, spindle speed and feed rate will be solve these 2 problems. For conducting the experiment, CNC Edu lathe machine was used to carry out the experiment, a WNGN type of HSS insert tool was used to cut the work-piece and the work-piece that used for this experiment is PVC rod. Besides that, an accelerometer that connect with the B&K handheld analyzer was used to determine and record the vibration value. Surface roughness tester was used to determine and record the roughness value on the surface of the work-piece. After conducting the experiment, the response which are vibration and surface roughness, and the 3 factors which are those parameters was validated in the DOE software. This DOE software will optimize the result after validating them and generates the significant model with the optimum result. Then, this optimum result was testing and running again to obtain the percentage error. Hence, the chattering and surface roughness can be optimize by using these 3 parameter which are cutting depth, spindle speed and feed rate. In a nut shell, the vibration will reduces when the depth of cut is decrease and the surface roughness will reduces when the feed rate is decrease and gives better surface.