For tool $$A,$$ Taylor’s tool life exponent $$(n)$$ is $$0.45$$ and constant $$(K)$$ is $$90.$$ Similarly for tool $$B,$$ $$n=0.3$$ and $$K=60.$$ The cutting speed (in $$m/min$$) above which tool $$A$$ will have a higher tool life than tool $$B$$ is

In a machining experiment, tool life was found to vary with the cutting speed in the following manner

What is percentage increase in tool life when the cutting speed is halved.

In a machining experiment, tool life was found to vary with the cutting speed in the following manner

The exponent $$(n)$$ and constant $$(K)$$ of the Taylor's tool life equation are

In a single point turning tool, the side rake angle and orthogonal rake angle are equal. $$\varphi $$ is the principle cutting edge angle and its range is $$0$$ to $$90.$$ The chip flows in the orthogonal plane. The value of $$\varphi $$ is closer to