1

GATE PI 2002

Subjective

+5

-0

A cutting tool is designated in 'Orthogonal Rake System' as:
$$${0^ \circ } - {0^ \circ } - {6^ \circ } - {6^ \circ } - {25^ \circ } - {75^ \circ } - 0.8\,\,mm.$$$

The following data were given

$${S_0} = $$ feed $$=0.12$$ $$mm/rev$$

$$T=$$ depth of cut $$=2.0$$ $$mm$$

$${a_2} = $$ chip thickness $$=0.22$$ $$mm$$

$${V_f} = $$ chip velocity $$=52.6$$ $$m/min$$

$${\tau _s} = $$ dynamic yield shear strength $$=400$$ $$MPa$$

$${P_z} = $$ main cutting force $$ = {S_0}\,t\,{\tau _s}\left( {\zeta \,\sec y - \tan \gamma + 1} \right)$$

The following data were given

$${S_0} = $$ feed $$=0.12$$ $$mm/rev$$

$$T=$$ depth of cut $$=2.0$$ $$mm$$

$${a_2} = $$ chip thickness $$=0.22$$ $$mm$$

$${V_f} = $$ chip velocity $$=52.6$$ $$m/min$$

$${\tau _s} = $$ dynamic yield shear strength $$=400$$ $$MPa$$

$${P_z} = $$ main cutting force $$ = {S_0}\,t\,{\tau _s}\left( {\zeta \,\sec y - \tan \gamma + 1} \right)$$

Where $$\zeta = $$ chip reduction coefficient and $$\gamma = $$ orthogonal rake.

The main cutting force $$\left( {{P_z}} \right)$$ and cutting power assuming orthogonal machining are

2

GATE PI 2001

Subjective

+5

-0

In certain machining operation with a cutting speed of $$50$$ $$m/min,$$ tool life of $$45$$ minutes was observed, when the cutting speed was increased to $$100$$ $$m/min,$$ the tool life decreased to $$10$$ minutes. The cutting speed for maximum productivity, if tool change time is $$2$$ minutes is

3

GATE PI 2001

Subjective

+5

-0

Tool life in drilling steel using $$HSS$$ drill is expressed as $${T^{0.2}} = 9.8\,\,{D^{0.4}}\,\,/\,\,V\,{s^{0.5}}$$ where $$D$$ is the drill diameter (in $$mm$$), $$T$$ is the tool life (in minutes), $$V$$ is the cutting speed (in $$m/min$$) and $$s$$ is the feed ($$mm/rev$$). The feed is set at maximum possible value of $$0.4$$ $$mm/rev$$ for a given drill diameter of $$30mm.$$ The length of drilling is $$50mm.$$ The machine hour rate Rs $$60$$ and the cost of drill is Rs. $$400.$$

$$i)$$ For the given conditions, the tailor's exponent and constant are .............

$$ii)$$ The optimum cutting speed, $${V_{opt}},$$ neglecting the work-piece and tool changing times is

4

GATE PI 1995

MCQ (Single Correct Answer)

+5

-1.5

In an orthogonal machining experiment using a tool having $${6^ \circ }.$$ Rake angle, the following data were collected. Cutting speed $$0.5$$ $$m/sec,$$ width of cut $$3$$ $$mm,$$ depth of cut $$1mn,$$ chip thickness $$1.5mm.$$ Assuming that shearing takes place under minimum energy condition,

The coefficient of friction between the chip tool interfaces will be

Questions Asked from Metal Cutting (Marks 5)

Number in Brackets after Paper Indicates No. of Questions

GATE PI Subjects

Engineering Mechanics

Strength of Materials

Theory of Machines

Engineering Mathematics

Machine Design

Fluid Mechanics

Thermodynamics

Casting

Joining of Materials

Metal Forming

Machine Tools and Machining

Metrology

Industrial Engineering