In orthogonal turning of low carbon steel pipe with principal cutting edge angle of $$90,$$ the main cutting force is $$1000$$$$N$$ and the feed force is $$800N.$$ The shear angle is $$25$$ and orthogonal rake angle is zero. Employing Merchants theory, the ratio of friction force to the normal force acting on the cutting tool is

In orthogonal turning of a low carbon steel bar of diameter $$150mm$$ with uncoated carbide tool, the cutting velocity is $$90m/min,$$ The feed is $$0.24mm/rev$$ and the depth of cut is $$2mm.$$ The chip thickness obtained is $$0.48$$$$mm.$$ If the orthogonal rake angle is zero, and the principle cutting edge angle is $$90,$$ the shear angle in degrees is

A low carbon steel bar of $$147$$ $$mm$$ diameter with length of $$630$$ $$mm$$ is being turned with uncoated carbide insert. The observed tool lives are $$24$$ and $$12$$ for cutting velocities of $$90$$ $$m/min$$ and $$120$$ $$m/min$$ respectively. The feed and depth of cut are $$0.2$$ $$mm/rev$$ and $$2$$ $$mm$$ respectively. Use the unmachined diameter to calculate the cutting velocity.

Neglect over travel or approach of the tool. When tool life is $$20min,$$ the machining time in $$min$$ for a single pass is

In an orthogonal machining operation:
$$\,\,\,\,\,\,\,\,\,\,$$Uncut thickness $$\,\,\,\,\,$$ $$= 0.5$$ $$mm$$
$$\,\,\,\,\,\,\,\,\,\,$$Cutting speed $$\,\,\,\,\,\,\,\,\,\,$$ $$= 20$$ $$m/min$$
$$\,\,\,\,\,\,\,\,\,\,$$Width of cut $$\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ $$= 5$$ $$mm$$
$$\,\,\,\,\,\,\,\,\,\,$$Chip thickness $$\,\,\,\,\,\,\,\,$$ $$= 0.7$$ $$mm$$
$$\,\,\,\,\,\,\,\,\,\,$$Thrust force$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ $$= 200$$ $$N$$
$$\,\,\,\,\,\,\,\,\,\,$$Cutting force $$\,\,\,\,\,\,\,\,\,\,\,\,$$ $$= 1200$$ $$N$$
$$\,\,\,\,\,\,\,\,\,\,$$Rake angle $$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ $$ = {15^ \circ }$$
Assume Merchant’s theory

The coefficient of friction at the tool chip interface is