Manufacturing Processes 1
(MDP 114)
First Year,
Mechanical Engineering Dept.,
Faculty of Engineering,
Fayoum University
Dr. Ahmed Salah Abou Taleb
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Machining Operations & Machine Tools
Turning
Planner Milling
Gears Drilling
Machine
Screw
Shaper
Thread
Saw Broacher
2
Classifications of Machined Parts
1. Rotational - cylindrical shape
2. Non-rotational (also called prismatic) – block
or plate
Machined parts are classified as: (a) rotational, or (b) non-rotational,
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Part Geometry
Each machining operation produces a characteristic part
geometry due to two factors:
1. Relative motions between the tool and the
workpart.
• Generating – part geometry is determined by the feed
trajectory of the cutting tool.
2. Shape of the cutting tool.
• Forming – part geometry is created by the shape of the
cutting tool.
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Part Geometry
Generating shape: (a) straight turning, (b) taper turning,
(c) contour turning, (d) plain milling, (e) profile milling
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Part Geometry
Forming to create shape: (a) form turning, (b) drilling, and
(c) broaching
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Part Geometry
Combination of forming and generating to create shape:
(a) thread cutting on a lathe, and (b) slot milling
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Turning/Lathe
Machine
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Definition
Turning/Lathe is a single point cutting tool machine,
which removes the metal from a rotating piece of
work to generate the required cylindrical shape
&size.
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Types of Turning/Lathe
Engine Turning/Lathe:
The most common form of lathe, motor driven and comes
in large variety of sizes and shapes.
Bench Turning/Lathe:
A bench top model usually of low power used to make
precision machine small work pieces.
Tracer Turning/Lathe:
a lathe that has the ability to follow a template to copy a
shape or contour.
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Types of Turning/Lathe
Automatic Turning/Lathe:
A lathe in which the work piece is automatically fed and
removed without use of an operator. Cutting operations
are automatically controlled by a sequencer of some form
Turret Turning/Lathe:
lathe which have multiple tools mounted on turret either
attached to the tailstock or the cross-slide, which allows for
quick changes in tooling and cutting operations.
Computer Controlled Turning/Lathe:
A highly automated lathe, where both cutting, loading, tool
changing, and part unloading are automatically controlled
by computer coding. 11
Turning/Lathe Machine
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Turning/Lathe Machine
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Turning/Lathe Machine
Head Stock
Tail Stock
Bed
Feed/Lead Screw Carriage
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Size of Turning/Lathe Machine
Workpiece Length Swing
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Size of Turning/Lathe Machine
Example: 300 - 1500 Lathe
• Maximum Diameter of Workpiece that can
be machined
= SWING (= 300 mm)
• Maximum Length of Workpiece that can be
held between Centers (=1500 mm)
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Lathe Operations
Turning: produce straight, conical, curved, or grooved workpieces
Facing: to produce a flat surface at the end of the part or for
making face grooves.
Drilling: to produce a hole by fixing a drill in the tailstock
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Lathe Operations
Boring: to enlarge a hole or cylindrical cavity made by a previous
process or to produce circular internal grooves.
Threading: to produce external or internal threads
Knurling: to produce a regularly shaped roughness on cylindrical
surfaces
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Lathe Operations
Contouring: tool follows a contour that is other than straight, thus
creating a contoured form.
Chamfering: Cutting edge cuts an angle on the corner of the
cylinder, forming a "chamfer".
Cut-off: Tool is fed radially into rotating work at some location to
cut off end of part.
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Lathe Operations
Threading: Pointed form tool is fed linearly across surface of
rotating workpart parallel to axis of rotation at a large feed rate,
thus creating threads.
Face Grooving:
Taper Turning:
Cutting with a form Tool:
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Methods of Holding the Work
• Holding the work between centers.
• Chuck.
• Mandrel.
• Collet.
• Face plate.
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Work holding Devices Centers
Headstock center Tailstock center
(Live Centre) (Dead Centre)
Workpiece
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Workholding Devices .. Chucks
Three jaw Four Jaw
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Work holding Devices. Chucks
Three jaw chuck
This is dependant chuck
has three jaws for holding
cylindrical shapes, which
are adjusted collectively.
Four-Jaw Chuck
This is independent
chuck generally has four
jaws for holding square
and rectangle shapes,
which are adjusted
individually on the
chuck face by means of
adjusting screws 24
Work holding Devices . Mandrels
Workpiece (job) with a hole
Workpiece Mandrel
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Work holding Devices .
Collet
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Work holding Devices .
Face Plate
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Operating/Cutting Conditions
1. Cutting Speed v
2. Feed f
3. Depth of Cut d
Tool post Workpiece
N (rev/min)
Chip
S
D
Tool peripheral
speed (m/min)
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Operating/Cutting Conditions
Tool post Workpiece
Chip N (rev/min)
S
Tool peripheral
D
speed
(m/min)
Relative tool travel in 1 rotation = πD
Peripheral speed S = πDN
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Operating/Cutting Conditions
D – Diameter (mm)
N – Revolutions per Minute (rpm)
ν = πDN/1000 m/min
The Peripheral Speed of Workpiece past the
Cutting Tool
=Cutting Speed
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Operating/Cutting Conditions
Fed (f) – the distance the tool advances for every
rotation of workpiece (mm/rev)
Fed rate (fr) – linear travel rate (mm/min)
fr = f N
D1 D2
f
Feed 31
Operating/Cutting Conditions
Depth of cut (d) perpendicular distance
between machined surface and uncut
surface of the Workpiece
d = (D1 – D2)/2 (mm)
D1 D2
d Depth
of Cut
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Operating/Cutting Conditions
Cutting speed
Workpiece
Depth of cut (d)
N
Machined
surface
Chuck Feed (f ) Chip
Tool Depth of cut
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Operating/Cutting Conditions
Material Removal Rate (MRR):
Volume of material removed in one revolution
MRR = D d f mm3
• Job makes N revolutions/min
MRR = D d f N (mm3/min)
• In terms of v MRR is given by
MRR = 1000 v d f (mm3/min)
MRR = D d f N
(mm)(mm)(mm/rev)(rev/min) = mm3/min
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Operating/Cutting Conditions
Machining Time (Tm): required time to machine one pass.
• Job length (L) mm, Feed (f ) mm/rev, speed (N) rpm,
outer diameter (D0) mm, cutting speed (v) mm/min,
feed rate (fr) mm/min
L L L D0
Tm min
f N fr fv
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Operating/Cutting Conditions
Manufacturing Time: the overall time to produce the
product.
Manufacturing time= Machining Time
+ Setup Time
+ Moving Time
+ Waiting Time
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Operating/Cutting Conditions
• Workpiece Material
• Tool Material
• Tool signature
• Surface Finish
• Accuracy
• Capability of Machine Tool
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Operations on Lathe ..
Operations on Lathe
• Turning • Chamfering
• Facing • Taper turning
• knurling
• Drilling
• Grooving
• Threading
• Parting
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Operations on Lathe .. Turning
Cylindrical job
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Operations on Lathe .. Turning ..
Cylindrical job
Workpiece
Cutting
speed Depth of cut (d)
N
Machined
surface
Chuck Feed Chip
Tool
Depth of cut
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Operations on Lathe ..
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
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Operations on Lathe .. Facing
Flat Surface/Reduce length
Chuck Workpiece
d
Machined
Face
Cutting
speed Depth of
cut
Tool Feed 42
Operations on Lathe .. 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
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Operations on Lathe ..
Facing ..
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Operations on Lathe ..
Eccentric Turning
4-jaw Axis of job
chuck
Ax
Cutting Eccentric peg
speed (to be turned)
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Operations on Lathe ..
Knurling
• Produce rough textured surface
– For Decorative and/or Functional Purpose
• Knurling Tool
A Forming Process
MRR~0
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Operations on Lathe ..
Knurling
Knurled surface
Cutting
speed
Feed Movement
for depth
Knurling tool
Tool post
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Operations on Lathe ..
Knurling ..
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Operations on Lathe ..
Grooving
• Produces a Groove on
workpiece
• Shape of tool shape of
groove
• Carried out using Grooving Tool
A form tool
• Also called Form Turning
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Operations on Lathe ..
Grooving ..
Shape produced
by form tool Groove
Feed or Grooving
Form tool depth of cut tool
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Operations on Lathe ..
Cut Off
• Cutting workpiece into Two
• Similar to grooving
• Parting Tool
• Hogging – tool rides over – at slow feed
• Coolant use
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Operations on Lathe .. Cut Off
Feed
Parting tool 52
Operations on Lathe ..
Chamfering
Chamfer
Feed
Chamfering tool 53
Operations on Lathe .. Chamfering
Beveling sharp machined edges
Similar to form turning
Chamfering tool – 45°
To
• Avoid Sharp Edges
• Make Assembly Easier
• Improve Aesthetics
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Operations on Lathe .. Taper Turning
• Taper: tan α = D1 – D2 / 2L
90°
D1 D2
B C
A L 55
Operations on Lathe .. Taper Turning..
Conicity K = D1 – D2 / L
Methods
• Form Tool
• Swiveling Compound Rest
• Taper Turning Attachment
• Simultaneous Longitudinal and Cross
Feeds
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Operations on Lathe .. Taper Turning ..
By Form Tool
Workpiece Taper
Form Direction
Straight of feed
cutting edge tool
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Operations on Lathe .. Taper Turning ,,
By Compound Rest
Dog
Mandrel Tail stock quill
Tail stock
Face plate Direction of feed
Tool post & Compound rest
Tool holder Slide
Compound rest
Cross slide Hand crank
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Operations on Lathe .. Drilling
Drill – cutting tool – held in TS – feed from TS
Quill
Drill clamp moving
quill
Tail stock
Feed
Tail stock clamp
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Operations on Lathe ..
Process Sequence
• How to make job from raw material 45 long
x 30 dia.?
15 Steps:
•Operations
•Sequence
20 dia •Tools
•Process
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60
Operations on Lathe .. Process Sequence ..
Possible Sequences
• TURNING - FACING - KNURLING
• TURNING - KNURLING - FACING X
• FACING - TURNING - KNURLING
• FACING - KNURLING - TURNING X
• KNURLING - FACING - TURNING X
• KNURLING - TURNING – FACING X
What is an Optimal Sequence?
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Simple Problems
Problem -1
A mild steel rod having 50 mm diameter and 500 mm length is to
be turned on a lathe. Determine the machining time to reduce the
rod to 45 mm in one pass when cutting speed is 30 m/min and a
feed of 0.7 mm/rev is used.
Solution
Given data: D = 50 mm, Lj = 500 mm
v = 30 m/min, f = 0.7 mm/rev
Substituting the values of v and D in
V = ΠDN/1000 M/min
Required spindle speed as: N = 191 rpm
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Simple Problems
Problem -2
Determine the angle at which the compound rest would
be swiveled for cutting a taper on a work piece having a
length of 150 mm and outside diameter 80 mm. The
smallest diameter on the tapered end of the rod should be
50 mm and the required length of the tapered portion is
80 mm.
Solution
Given data: D1 = 80 mm, D2 = 50 mm, Lj = 80 mm (with
usual notations)
tan = (80-50) / 280 or = 10.620
The compound rest should be swiveled at 10.62o
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