| Summary: | The interest in using 5-axis CNC milling machine has increased in recent years
which is used for manufacturing complex-shape workpiece and reduce set-up
time. Error occured in a machine mainly caused by controller, structure, and machining error or the combination of those three. Error in machine structure could be happened along process starting from design, manufacture, and assembly process. Because of that reason, an investigation in increasing machine accuracy and precision is needed. the te Erros could be obtained by rotary table calibration process where measuring instrument placed in the same direction with linear movement axis : X, Y, Z and rotation : A and C axis. Errors in load testing are achieved by measuring the actual profile of manufacturing product. Aluminium casting was manufactured to perform st. A 60 degree angle was choose to perform testing in C axis with 4 different depth of cut: 0.5 mm, 0.75 mm, 1 mm and 1.25 mm. Besides, there are variation in feed rates: 75 mm/min, 100 mm/min, 125 mm/min and 150 mm/min. A 45 degree angle was choose to perform testing in A axis with depth of cut 0.5 mm and 4 different feed rates: 100 mm/min, 200 mm/min, 300 mm/min and 400 mm/min. Error measurement in A-axis before compensation is -1,2267o in average where after
compensation the average of error reduces to 0,083o. The same case happened in C-axis, where before compensation is -0,184o in average where after compensation the average of error reduces to 0,003o at feed rate of 75 mm/min. On the other hand, the same trend showed in error measurements but with different DoC and feed rates. The average error by using the original G-code is larger than by using the modified one. Based on the above results, it could be concluded that calibration process in machine structure, calibration process by adjusting the number of steps in motor stepper, and error compensation in rotary table motion could improve the accuracy and precision of mini 5-axis CNC milling machine type tilt rotary table prototype.
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