The following data refers to an orthogonal machining of mild steel with a single point $$HSS$$ tool. Rake angle of tool $$ = {10^ \circ },$$ uncut chip thickness $$=0.3mm,$$ width of cut $$=2.0mm,$$ single plane shear angle $$ = {36^ \circ },$$ shear strength of mild steel $$=450$$ $$MPa,$$ using Merchants analysis

The coefficient of friction between the chip and tool will be

A single point cutting tool with a nose radius of $$0.4$$ $$mm$$ was used to turn a component in a lathe employing a feed rate of $$0.3$$ $$mm/rev.$$ If the feed-rate is doubled, the ideal surface roughness (peak-to-valley height) produced on the component will increase by a factor of

Tool life equation for two tools under consideration are as follows

$$\eqalign{ & HSS:\,\,\,\,\,\,\,\,\,\,\,\,\,V{T^{0.2}} = 150 \cr & Carbide:\,\,\,\,\,\,V{T^{0.3}} = 250 \cr} $$
Where $$V$$ is the cutting speed in $$m/min$$ and $$T$$ is the tool life in $$min.$$ The breakdown cutting speed above which the carbide tool will be beneficial is