• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.6
• /
• pp.1121-1140
• /
• 1992

In metal cutting the shape of generated chip varies according to cutting conditions, characteristics of workpiece and geometry of cutting tool. The best surface roughness of machined workpiece is obtained when generating flow type contrinuous chip. If the generated chip is not broken, that is not only tangled workpiece and cutting tool, but also may give damage on the machined surface of workpiece or danger for a operator. The flow type continuous chip may bring the low productivity in high speed any heavy cutting, automatic machining process and non-human factory. There are two type of chip break process ; controlling cutting condition and using chip breaker. In present study we carried out the experiment on new type chip breaker compared with conventional type and proved the efficiency of a new type and showed the chip break condition to be applied in actual metal cutting. In the experiment SM 20 C as a workpiece material and WC as a tool material were used and cutting speed of 30-150m/min, feed of 0.071-0.210mm/rev and depth of cut of 1mm were applied as cutting condition. The results of the experiment are as follows : (1) The mechanism of chip curl can be explained more clearly by plastic flow of workpiece material and moment of shearing force. (2) The most effective radius of curled chip and flat distance from cutting edge is 2.0-2.5mm and 1.5mm in both types. (3) The effective inclination angle of chip break surface and side cutting edge angle are 30.deg.- 45.deg. and 20.deg. in conventional type, while the radius of arc surface, lower arc angle A, upper arc angle B and side cutting edge angle are 3mm, 20.deg.- 45.deg., 0.deg.- 45.deg. and 10.deg.- 20.deg. in new type. (4) The probability to be obtained 100% chip breaking ratio is much higher in new type than in conventional type.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.11 no.6
• /
• pp.1005-1013
• /
• 1987

For the factory automation and unmanned machine operation, it is very important to manufacture highly reliable and efficient chip breakers for optimal chip control. In this research, using the CALMA CAD/CAM SYSTEM, the manufacturing process of 3-dimensional chip breakers is established. Using the results of the cutting test of the selected chip breakers with double-step grooves, the chip breaking mechanism is schematically analysed. An expression for the chip breaking relation is derived which considers chip material behavior following LUDWIK's stress-strain curve, chip breaking criterion and the shape of chip breakers. This contains the thickness of chip, the radius of chip curl, and the mechanical properties of chip materials. It is found that the expression agrees very closely with the experimental results.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.12
• /
• pp.120-126
• /
• 2002

The needs of ultra-precisely machined parts are increasing more and more. But the experimental data required to ultra precision machining of nonferrous metal is insufficient. The behavior of cutting in micro cutting area is different from that of traditional cutting because of the size effect. Copper is widely used as optical parts such as LASER reflector's mirror and multimedia instrument. In experimental, after oxygen-free copper is machined by ultra precision machine with natural mono crystal diamond tool (NCD) and synthetic poly crystal diamond tool (PCD), we compared chip formation and tool's wear according to used tool. Also, we researched optimized cutting condition with the results measured according to cutting condition such as spindle speed, feed rate and depth of cut. As a result, the optimal working condition that makes good surface roughness is obtained. The surface roughness is good when spindle speed is above 80 m/min, and feed rate is small and depth of cut is above 0.5 ${\mu}{\textrm}{m}$. In cutting of klystron anode and cavity 3.2 nmRa of surface roughness is obtained.