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Workshop Practice (ME192) Credits: 3 Contacts: Mail: [email protected] Web: http://www.ajourneywithtime.weebly.com
Workshop Practice (ME192)
Credits: 3
Contacts:
Mail: [email protected]
Web: http://www.ajourneywithtime.weebly.com
Exp 03: To make a pin as given profile from a φ20 mm mild steel
rod in a lathe.
Material Required: mild steel bar of φ35 mm
Tool and Accessories required:
Lathe machine, 3-jaw chuck, facing tool, turning tool, grooving
tool, chamfering tool, marking and measurement tool,
combination drill
Drawing: job or Pin profile to be made
Procedures: Select the speed, feed and depth of cut for different
operations Load the job on three jaw chuck Perform facing operation on both end of the job by a
combination drill Hold the job between centers using lathe dog Turn the job to reduce diameter to φ x1 mm over
length of L1 mm and to φ x2 mm by a turning tool Chamfering one end by chamfering tool Grooving at required position by using grooving tool Check the dimensions Precautions: Conclusion:
Lathe: A Lathe is an important and oldest known machine tool in any workshop.
The job to be machined is held and rotated in a chuck, face plate, catch plate, between centres etc. A suitable cutting tool is advanced against rotating job. Since the cutting tool material is harder than the workpiece, the metal is easily removed from the job in the form of chip. Cutting tool used is a single point cutting tool.
Common operations performed on lathe machine:
Some common operations are facing, turning, chamfering, parting off, drilling, knurling, boring, thread cutting etc
Cutting speed, feed and depth of cut:
Cutting speed(V) : The cutting speed is the distance travelled by a point on the outer surface of the work in one minute. It is expressed in meters per minute. or
The Peripheral Speed of Workpiece past the Cutting Tool
V = πDN/1000 m/min
where D is the diameter of the work in mm
N is the r.p.m. of the work
Feed:
The feed of a cutting tool in a lathe work is the distance the tool advances for each
revolution of the work. Feed is expressed in millimeters per revolution.
Depth of cut: The depth of cut is the perpendicular distance measured
from the machined surface to the uncut surface of the workpiece. It
is expressed in millimeters.
In a lathe, the depth of cut is expressed as follows
Depth of cut = (D1 – D2) / 2
Where D1- diameter of the work surface before machining
D2 - diameter of the machined surface
Three-jaw chuck:
- For holding cylindrical stock centered.
- For facing/center drilling the end of your aluminum stock
f
Feed
DD 21
d Depth
of Cut
DD 21
3 Operating Conditions
Chip
Machined
surface
Workpiece
Depth of cutTool
Chuck
N
Feed (f )
Cutting speed
Depth of cut (d)
• Turning
• Facing
• knurling
• Grooving
• Parting
• Chamfering
• Taper turning
• Drilling
• Threading
Op
era
tio
ns
on
La
the
..
Turning ..
Cylindrical job
Cutting
speed
Chip
Workpiece
Depth of cut (d)
Depth of cutTool
FeedChuck
N
Machined
surface
Op
era
tio
ns
on
La
the
..
Turning ..
• Excess Material is removed to reduce Diameter
• Cutting Tool: Turning Tool
a depth of cut of 1 mm will reduce diameter by 2 mm
Op
era
tio
ns
on
La
the
..
Facing
Flat Surface/Reduce length
Depth of cut
Feed
WorkpieceChuck
Cutting
speed
Tool
d
Machined Face
Op
era
tio
ns
on
La
the
..
Facing ..
• machine end of job Flat surface
or to Reduce Length of Job
• Turning Tool
• Feed: in direction perpendicular to workpiece axis
–Length of Tool Travel = radius of workpiece
• Depth of Cut: in direction parallel to workpiece axis O
pe
ratio
ns
on
La
the
..
Grooving
• Produces a Groove on workpiece
• Shape of tool shape of groove
• Carried out using Grooving Tool A form tool
• Also called Form Turning
Op
era
tio
ns
on
La
the
..
Grooving .. O
pe
ratio
ns
on
La
the
..
Shape produced
by form tool Groove
Grooving
toolFeed or
depth of cutForm tool
Parting
• Cutting workpiece into Two
• Similar to grooving
• Parting Tool
• Tool rides over – at slow feed
• Coolant use
Op
era
tio
ns
on
La
the
..
Chamfering O
pe
ratio
ns
on
La
the
..
Chamfering tool
Feed
Chamfer
Chamfering
Beveling sharp machined edges
Similar to form turning
Chamfering tool – 45°
To • Avoid Sharp Edges
• Make Assembly Easier
Op
era
tio
ns
on
La
the
..
SINGAL POINT CUTTING TOOL FOR LATHE
DIFFERENT LATHE OPERATIONS
FORM TOOL
References
Books
• work shop Technolgy by Hajra choudry
• Advances in Manufacturing Technology C.J Thomas
