In DC arc welding, if leads are arranged in work as Negative pole of the welding arc and electrode as Positive pole of the welding arc, the arrangement is known as
Fusion
Reverse polarity
Forward welding
Direct polarity
Correct Answer :
B. Reverse polarity
Related Questions
In machining metals, chips break due to __________ of work material.
Toughness
Ductility
Elasticity
Work hardening
In ultrasonic machining, the metal is removed by
Using abrasive slurry between the tool and work
Direct contact of tool with the work
Maintaining an electrolyte between the work and tool in a very small gap between the two
Erosion caused by rapidly recurring spark discharges between the tool and work
Which of the following statement is incorrect with reference of lathe cutting tools?
The flank of the tool is the surface or surfaces below and adjacent to the cutting edges
The nose is the corner, arc or chamfer joining the side cutting and the end cutting edges
The heel is that part of the tool which is shaped to produce the cutting edges and face
The base is that surface of the shank which bears against the support and takes tangent pressure of the cut
The rake angle of a single point cutting tool corresponds to _________ of a twist drill.
Lip clearance angle
Helix angle
Point angle
Chisel edge angle
In an orthogonal cutting, the depth of cut is halved and the feed rate is double. If the chip thickness ratio is unaffected with the changed cutting conditions, the actual chip thickness will be
Doubled
Halved
Quadrupled
Unchanged
The process of removing metal by a cutter which is rotated in the same direction of travel of workpiece, is called
Up milling
Down milling
Face milling
End milling
The soft grade grinding wheels are denoted by the letters
A to H
I to P
Q to Z
A to P
In drilling brass, a drill with
Zero helix angle is used
Low helix angle is used
High helix angle is used
Any helix angle can be used
When the cutting edge of the tool is dull, then during machining
Continuous chips are formed
Discontinuous chips are formed
Continuous chips with built-up edge are formed
No chips are formed
In ultrasonic machining, tool is made of
Tungsten carbide
Brass or copper
Diamond
Stainless steel
Lapping is an operation of
Making a cone-shaped enlargement of the end of a hole
Smoothing and squaring the surface around a hole
Sizing and finishing a small diameter hole
Producing a hole by removing metal along the circumference of a hollow cutting tool
The lip angle of a single point tool is usually
20° to 40°
40° to 60°
60° to 80°
None of these
The cutting angle of a flat drill varies from
3° to 8°
20° to 30°
60° to 90°
90° to 120°
EDM machining is applied for
Shaping carbide dies and punches having complicated profiles
Making large number of small holes in sieves and fuel nozzles
Embossing and engraving on harder materials
All of these
During the execution of a CNC part program block NO20 GO2 X45.0 Y25.0 R5.0 ; the type of tool motion will be
Circular Interpolation − clockwise
Circular Interpolation − counter clockwise
Linear Interpolation
Rapid feed
The operation of producing grooves around the periphery of a cylindrical or conical workpiece is called
Profile milling
Gang milling
Saw milling
Helical milling
Crater wear is predominant in
Carbon tool steels
Tungsten carbide tools
High speed steel tools
Ceramic tools
The depth of cut in drilling is __________ the drill diameter.
Equal to
One-fourth
One-half
Double
Which of the following engineering materials is the most suitable candidate for hot chamber die casting?
Low carbon steel
Titanium
Copper
Tin
For turning small taper on long workpiece, the suitable method is
By a form tool
By setting over the tail stock
By a taper turning attachment
By swivelling the compound rest
The hardness of a grinding wheel is specified by
Brinell hardness number
Rockwell hardness number
Vickers pyramid number
Letter of alphabet
If a gas metal arc process uses a low arc voltage and the arc is continuously interrupted as the molten electrode metal fills up the arc gap is known as
ARC
Short ARC
ARC length
ARC blow
In order to prevent tool from rubbing the work _________ on tools are provided.
Rake angles
Relief angles
Face angles
None of these
The specific cutting energy used for establishing the machinability of the metal depends upon its
Coefficient of friction
Microstructure
Work hardening characteristics
All of these
The addition of lead, sulphur and phosphorus to low carbon steels, help to
Reduce built up edge
Break up chips
Improve machinability
All of these
In reaming process
Metal removal rate is high
High surface finish is obtained
High form accuracy is obtained
High dimensional accuracy is obtained
A lathe with four steps on the cone pulley and with back-gears will have
Four direct speeds
Four indirect speeds
Four direct and four indirect speeds
Eight indirect speeds
In lapping operation, the amount of metal removed is
0.005 to 0.01 mm
0.01 to 0.1 mm
0.05 to 0.1 mm
0.5 to 1 mm
Ultrasonic machining is best suited for
Tool steels
Sintered carbides
Glass
All of these
The method of centre less grinding used to produce taper is
In-feed grinding
Through feed grinding
End feed grinding
Any one of these