Influence of work material, cutting conditions and rigidity of tool holders on machine tool chatter

• Main Author: Amin, A. K. M. Nurul
• Format: Conference or Workshop Item
• Language: English
• Published: 1992
• Subjects: TS200 Metal manufactures. Metalworking
• Online Access: http://irep.iium.edu.my/29505/1/1992_Influence_of_work_materials%2C_cutting_conditions_and_rigidi.pdf; http://irep.iium.edu.my/29505/
• Institution: Universiti Islam Antarabangsa Malaysia

Experimental investigation have been carried out to determine the influence of job materials, cutting speed and stiffness of tool holder on chatter phenomenon which arises during metal cutting operation. Experiments were performed on Engine Lathe of model Celtic-14. Medium Carbon Steel Stainless Steel, Cast Iron and Brass were taken as work materials. Cemented Carbide containing 92% WC and 8% Co was taken as cutting tool material. Three different tool holders having different cross¬ sectional areas and, mechanical clamping arrangement for tool bits, were used. An experimental set-up, consisting of a function generator, amplifiers, vibrator head, pressure transducer, oscilloscope and camera were used for determining the natural frequency of the different elastic elements, including the tool holders. Frequency and amplitude of vibration and chatter were determined by two methods - by using the above mentioned experimental set-up and by measuring the average distance between two vibration marks on job surface or between two chip elements using an instrumental microscope. It has been established by the experimental investigation that single or multiple number of horizontal segments of the frequency versus cutting speed curve correspond to chatter, which appear within narrow range of cutting speeds during cutting of Brass and Cast-Iron; but within wide ranges of cutting speeds during cutting of Medium Carbon and stainless steel. Frequency of chatter corresponding to different horizontal segments of the frequency characteristic curve are almost-integer multiples (1, 2, 3, 4, etc.) of the natural frequency of tool holder. It has been also found that the amplitude of chatter and the range of cutting speed corresponding to the horizontal segments of the frequency characteristic curve decrease and these segments are shifted towards higher cutting speeds with an increase in the stiffness of the tool holder and vice versa. The lengths of the horizontal segments of the frequency characteristic curve decrease but their number increase with an increase in the "stiffness" of the instability of the chip formation process and brittleness of job materials.