In a single point turning operation with a cemented carbide and steel combination having a Taylor exponent of 0.25, if the cutting speed is halved, then tool life will become
Half
Two times
Eight times
Sixteen times
Correct Answer :
D. Sixteen times
Related Questions
Volume of a cube of side l and volume of a sphere of radius r are equal. Both the cube and the sphere are solid and of same material. They are being cast. The ratio of the solidification time of the cube to the same of the sphere is
(4π/6)³ × (r/l)⁶
(4π/6) × (r/l)²
(4π/6)² × (r/l)³
(4π/6)² × (r/l)⁴
Ceramic cutting tools are
Made by cold pressing of aluminium oxide powder
Available in the form of tips
Brittle and have low bending strength
All of these
Internal gear cutting operation can be performed by
Milling
Shaping with rack cutter
Shaping with pinion cutter
Hobbing
The ductile materials, during machining, produce
Continuous chips
Discontinuous chips
Continuous chips with built up edge
Either (A) or (C)
In gear hobbing
Only hob rotates
Only gear blank rotates
Both hob and gear blank rotates
Neither hob nor gear blank rotates
The tool life is said to be over if
Poor surface finish is obtained
There is sudden increase in cutting forces and power consumption
Overheating and fuming due to heat of friction starts
All of the above
When the end of a tap is tapered for about three or four threads, it is known as a
Taper tap
Bottoming tap
Second tap
None of these
A feed gear box for a screw cutting lathe is designed on the basis of
Geometric progression
Arithmetic progression
Harmonic progression
None of these
Gear burnishing is a process for
Surface finishing
Undercut gears
Cycloidal gears
Removing residual stresses from teeth roots
The operation of smoothing and squaring the surface around a hole is known as
Counter-sinking
Counter-boring
Trepanning
Spot facing
In oblique cutting system, the maximum chip thickness
Occurs at the middle
May not occur at the middle
Depends upon the material of the tool
Depends upon the geometry of the tool
Which of the following statement is wrong?
The diamond is the hardest tool material and can run at cutting speeds about 50 times that of high speed steel tool.
The ceramic tools can be used at cutting speeds 40 times that of high speed steel tools.
The cemented carbide tools can be used at cutting speeds 10 times that of high speed steel tools.
The ceramic tools can withstand temperature upto 600°C only.
In machining metals, surface roughness is due to
Feed marks or ridges left by the cutting tool
Fragment of built-up edge on the machined surface
Cutting tool vibrations
All of these
The primary purpose of a sprue in a casting mould is to
Feed the casting at a rate consistent with the rate of solidification.
Act as a reservoir for molten metal
Feed molten metal from the pouring basin to the gate
Help feed the casting until all solidification takes place
In drilling operation, the metal is removed by
Shearing
Extrusion
Shearing and extrusion
Shearing and compression
The hard grade grinding wheels are denoted by the letters
A to H
I to P
Q to Z
A to P
A drill bit of 20 mm diameter rotating at 500 r.p.m. with a feed rate of 0.2 mm/revolution is used to drill a through hole in a mild steel plate 20 mm thickness. The depth of cut in this drilling operation is
0.2 mm
10 mm
20 mm
100 mm
The correct sequence of tool materials in increasing order of their ability to retain their hot hardness is
Carbide, ceramic, cermet, borazon
Ceramic, carbide, borazon, cermet
Cermet, carbide, ceramic, borazon
Borazon, ceramic, carbide, cermet
The swing diameter over the bed is ________ the height of the centre measured from the bed of the lathe.
Equal to
Twice
Thrice
One-half
With the same tool life, the maximum material per minute is removed by
Increasing the cutting speed
Decreasing the cutting speed
Increasing the depth of cut
Increasing the feed rate
Two streams of liquid metal which are not hot enough to fuse properly result into a casting defect known as
Cold shut
Swell
Sand wash
Scab
The aluminium oxide abrasive is chiefly used for grinding
High speed steel
Carbon steel
Wrought iron
All of these
The trade name of a nonferrous cast alloy composed of cobalt, chromium and tungsten is called
Ceramic
Stellite
Diamond
Cemented carbide
When the tool moves parallel to the lathe axis, the movement is termed as
Cross feed
Angular feed
Longitudinal feed
Any one of these
The factor considered for evaluation of machinability is
Cutting forces and power consumption
Tool life
Type of chips and shear angle
All of these
In a particular type of welding, flux is prepared in the form of a coarse powder and granulated flux is spread over the joint. What is this type of welding process called?
Electric arc welding
Submerged arc welding
MIG welding
TIG welding
Misrun is a casting defect which occurs due to
Very high pouring temperature of the metal
Insufficient fluidity of the molten metal
Absorption of gases by the liquid metal
Improper alignment of the mould flasks
The stroke of a shaping machine is 250 mm. It makes 30 double strokes per minute. The overall average speed of operation is
3.75 m/min
5 m/min
7.5 m/min
15 m/min
If the helix angle of the drill is made _________ 30°, then the torque required to drive the drill at a given feed will be more.
Equal to
Less than
More than
None of these
In metal cutting operations, the shear angle is the angle made by the shear plane with the
Direction of the tool axis
Direction of tool travel
Perpendicular to the direction of the tool axis
Central plane of the workpiece