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First Year,
Mechanical Engineering Dept.,
Faculty of Engineering,
Fayoum University
Dr. Ahmed Salah Abou Taleb
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Manufacturing Processes 1(MDP 114)
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Machining Operations & Machine Tools
Machine
Turning
Milling
Drilling
Shaper
BroacherSaw
Screw Thread
Gears
Planner
Classifications of Machined Parts
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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
Turning/LatheMachine
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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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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.
Types of Turning/Lathe
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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
Types of Turning/Lathe
Turning/Lathe Machine
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Turning/Lathe Machine
Bed
Head StockTail Stock
CarriageFeed/Lead Screw14
Turning/Lathe Machine
Size of Turning/Lathe Machine
Workpiece Length Swing
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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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Size of Turning/Lathe Machine
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
Lathe Operations
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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
Lathe Operations
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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.
Lathe Operations
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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:
Lathe Operations
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Methods of Holding the Work
• Holding the work between centers.
• Chuck.
• Mandrel.
• Collet.
• Face plate.
Workpiece
Headstock center(Live Centre)
Tailstock center
(Dead Centre)
CentersW
ork
ho
ldin
g D
ev
ice
s
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Chucks
Three jaw Four Jaw
Wo
rkh
old
ing
De
vic
es
..
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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
ChucksW
ork
ho
ldin
g D
ev
ice
s.
Mandrels
Workpiece (job) with a hole
Wo
rk h
old
ing
De
vic
es
.
Workpiece Mandrel
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ColletW
ork
ho
ldin
g D
ev
ice
s.
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Face PlateW
ork
ho
ldin
g D
ev
ice
s.
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Operating/Cutting Conditions
1. Cutting Speed v
2. Feed f
3. Depth of Cut d
Workpiece
Tool
Chip
Tool post
S
peripheral
speed (m/min)
N (rev/min)
D
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Workpiece
Tool
Chip
Tool post
S
peripheral
speed
(m/min)
N (rev/min)
D
Relative tool travel in 1 rotation = πDPeripheral speed S = πDN
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Operating/Cutting Conditions
The Peripheral Speed of Workpiece past the Cutting Tool
=Cutting Speed
D – Diameter (mm)N – Revolutions per Minute (rpm)
ν = πDN/1000 m/min
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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
f
Feed
DD 21
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Operating/Cutting Conditions
Depth of cut (d) perpendicular distance between machined surface and uncut surface of the Workpiece
d = (D1 – D2)/2 (mm)
d Depth
of Cut
DD 21
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Operating/Cutting Conditions
Chip
Machined
surface
Workpiece
Depth of cutTool
Chuck
N
Feed (f )
Cutting speed
Depth of cut (d)
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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)
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Operating/Cutting Conditions
MRR = D d f N (mm)(mm)(mm/rev)(rev/min) = mm3/min
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
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Operating/Cutting Conditions
min0
vf
DL
f
L
Nf
LT
r
m
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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Operating/Cutting Conditions
Operations on Lathe
• Turning
• Facing
• knurling
• Grooving
• Parting
• Chamfering
• Taper turning
• Drilling
• Threading
Op
era
tio
ns
on
La
the
..
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TurningO
pe
ratio
ns
on
La
the
..
Cylindrical job
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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
..
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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
..
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Facing
Flat Surface/Reduce length
Depth of cut
Feed
WorkpieceChuck
Cutting
speed
Tool
d
Machined Face
Op
era
tio
ns
on
La
the
..
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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 axisO
pe
ratio
ns
on
La
the
..
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Facing ..O
pe
ratio
ns
on
La
the
..
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Eccentric Turning
Axis of job
Axis of lathe
Eccentric peg
(to be turned)
4-jaw
chuck
Cutting
speedOp
era
tio
ns
on
La
the
..
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Knurling
• Produce rough textured surface– For Decorative and/or Functional Purpose
• Knurling Tool
A Forming Process
MRR~0
Op
era
tio
ns
on
La
the
..
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KnurlingO
pe
ratio
ns
on
La
the
..
Knurling tool
Tool post
Feed
Cutting
speed
Movement
for depth
Knurled surface
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Knurling ..O
pe
ratio
ns
on
La
the
..
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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
..
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Grooving ..O
pe
ratio
ns
on
La
the
..
Shape produced
by form tool Groove
Grooving
toolFeed or
depth of cutForm tool
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Cut Off
• Cutting workpiece into Two
• Similar to grooving
• Parting Tool
• Hogging – tool rides over – at slow feed
• Coolant use
Op
era
tio
ns
on
La
the
..
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Cut OffO
pe
ratio
ns
on
La
the
..
FeedParting tool 52
ChamferingO
pe
ratio
ns
on
La
the
..
Chamfering tool
Feed
Chamfer
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Chamfering
Beveling sharp machined edges
Similar to form turning
Chamfering tool – 45°
To• Avoid Sharp Edges
• Make Assembly Easier
• Improve Aesthetics
Op
era
tio
ns
on
La
the
..
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Taper Turning
• Taper:
CB
AL
D90°
2D1
Op
era
tio
ns
on
La
the
..
tan α = D1 – D2 / 2L
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Taper Turning..
Methods• Form Tool• Swiveling Compound Rest• Taper Turning Attachment• Simultaneous Longitudinal and Cross
FeedsOp
era
tio
ns
on
La
the
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Conicity K = D1 – D2 / L
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Taper Turning ..By Form Tool
Op
era
tio
ns
on
La
the
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TaperWorkpiece
Straight
cutting edge
Direction
of feedForm
tool57
Taper Turning ,,By Compound Rest
Op
era
tio
ns
on
La
the
..
Face plate
Dog
Tail stock quill
Tail stock
Mandrel
Direction of feed
Compound rest Slide
Compound rest
Hand crank
Tool post &
Tool holder
Cross slide58
Drilling
Drill – cutting tool – held in TS – feed from TS
Op
era
tio
ns
on
La
the
..
Feed
Drill
Quill
clamp moving
quill
Tail stock clamp
Tail stock
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Process Sequence• How to make job from raw material 45 long
x 30 dia.?
20 dia
40
15
Op
era
tio
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on
La
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Steps:•Operations•Sequence•Tools•Process
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Process Sequence ..Possible Sequences
• TURNING - FACING - KNURLING
• TURNING - KNURLING - FACING
• FACING - TURNING - KNURLING
• FACING - KNURLING - TURNING
• KNURLING - FACING - TURNING
• KNURLING - TURNING – FACINGWhat is an Optimal Sequence?
Op
era
tio
ns
on
La
the
..
X
X
XX
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Simple ProblemsProblem -1A 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.
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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
Simple ProblemsProblem -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.
SolutionGiven data: D1 = 80 mm, D2 = 50 mm, Lj = 80 mm (with usual notations)tan = (80-50) / 280 or = 10.620The compound rest should be swiveled at 10.62o
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