GATE PI 2001
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GATE PI

1
For true centrifugal casting process with the axis of rotation in horizontal direction, an acceleration of $$75g,$$ where $$g$$ is the acceleration due to gravity, is required for sound casting. The relation between diameter. $$'D'$$ (in $$mm$$) and the rotational speed $$N$$ ($$1$$ $$rev/s$$) for this casting is $${N^2}D = $$ constant, determine the constant. Also calculate the mold speed (in $$rev/sec(c)$$ for casting $$CI$$ pipes of $$5m$$ long with outside and inside diameters of $$0.52m$$ and $$0.5m$$ respectively
2
Which of the following powders should be fed for effective oxy-fuel cutting of stainless steel
3
A weld is made using $$MIG$$ welding process with the following welding parameters: Current: $$200A;$$ Voltage: $$25V;$$ Welding speed: $$18$$ $$cm/min;$$ wire diameter: $$1.2$$ $$mm;$$ Wire feed rate: $$4$$ $$m/min;$$ Thermal efficiency of the process: $$65\% $$

The heat input per unit length of the weld in $$kJ/cm$$ is:

4
A weld is made using $$MIG$$ welding process with the following welding parameters: Current: $$200A;$$ Voltage: $$25V;$$ Welding speed: $$18$$ $$cm/min;$$ wire diameter: $$1.2$$ $$mm;$$ Wire feed rate: $$4$$ $$m/min;$$ Thermal efficiency of the process: $$65\% $$

The area of cross section of weld bead in $$m{m^2}$$ is:

5
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
6
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

7
In Whitworth quick return mechanism (used in shapers) the velocity of the $$ram$$ is maximum at
8
For $$50\% $$ penetration of work material, a punch with single shear equal to thickness will
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