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Microsoft PowerPoint - lecture 20 machining 2_students.ppt
MACHINING OPERATIONS
Turning and Related OperationsOutline
Turning a machining process in which a single- point tool remove material from the surface of a
vDo Df Turning and Related Operations
rotating work piece. (Lathe) df Drilling and Related Operations Milling Machining & Turning Centers Other Machining Operations Shaping and Planing Broaching Sawing Machinability
N = vDoDo D ff r = NfT = Lm fr
LRotational Speed= 2dFeed rateTime of machiningMRR = vfd
Material Removal RateDr. M. Medraj Mech. Eng. Dept. - Concordia University Mech 421/6511 lecture 20/1
Dr. M. Medraj Mech. Eng. Dept. - Concordia University Mech 421/6511 lecture 20/2Operations Related to Turning
Work HoldingContour turning
ChamferingFacing Taper turning
Form turning
mounting the work between centers using a "dog
three-jaw chuck
Cutoff
Threading
Boring
Drilling
Knurling
collet face plate for non-cylindrical workpartsEngine Lathe
Other Lathes & Turning Machine Toolroom Lathe and Speed Lathe Turret Lathe The tailstock is replaced with a turret Chucking Machines No tailstock Automatic Bar Machine Similar to chuck machine but with a collet A single- and multiple-spindle bar machines NC Lathe Boring Machines the stiffness of a boring bar Horizontal and VerticalDr. M. Medraj Mech. Eng. Dept. - Concordia University Mech 421/6511 lecture 20/5
Dr. M. Medraj Mech. Eng. Dept. - Concordia University Mech 421/6511 lecture 20/6Drilling and Related Operations Geometry of Twist drill
Shank, Neck and Drill body Helix angle, Point angle, Flute, cutting edge, Chisel edge, Margin Cutting conditions
Operation Related to DrillingSpindle rpm:
N = vDFeed rate:
f r = Nf
f(in/rev)
Reaming Tapping CounterboringMRR = D f rMetal Removal Rate: 4
For a through hole
For a blind hole
Countersinking Center drillingMachining time:
T = t + A d
Spot facingm T =r f r Drill press
Machine Tool for drilling
MillingA machine operation in which a workpart is fed past a rotating cylindrical tool with multiple edges. (milling machine) Upright drill Bench drill Radial drill Gang drill 2-6 drills together NC drill Vice, Jig and fixture
Upright drill press
Types:9 Peripheral milling
Slab, slotting, side and straddle milling Up Milling (Conventional) & down milling (Climb)9 Facing milling
Conventional, Partial face, end, profile, pocket & contour
Up MillingDown MillingRadial drill press
Large drill press designed for large partsDr. M. Medraj Mech. Eng. Dept. - Concordia University Mech 421/6511 lecture 20/9
(a) peripheral milling (b) face millingDr. M. Medraj Mech. Eng. Dept. - Concordia University Mech 421/6511 lecture 20/10Milling
Cutting Conditions
Slab slotting sidestraddle
Milling cutters Plain milling cutters Form milling cutters Face milling cutters End milling cutters Cutting conditions
Radial RakeAngle
ReliefAngleconventional face milling
Partial face milling
end milling
Spindle rotation speed:
N = vDpocket milling
Surface contouring
profile milling
Feed rate:
MRR:
f r = Nnt fMRR = wdf rMilling Machines
Machining Centers Machining center highly automated machine tool capable of performing multiple machining operations under CNC control. Automatic tool changer Pallet shuttles Automatic workpart positioninghorizontal knee-and-column
vertical knee-and-columnram type knee-and-column milling machine; ram can be adjusted in and out, and toolhead can be swiveled
CNC turning centerDr. M. Medraj Mech. Eng. Dept. - Concordia University Mech 421/6511 lecture 20/13
Dr. M. Medraj Mech. Eng. Dept. - Concordia University Mech 421/6511 lecture 20/14Mill-Turn Centers Highly automated machine tool that can perform turning, milling, anddrilling operations on a workpart General configuration of a turning center Can position a cylindrical workpart at a specified angle so a rotating cutting tool (e.g., milling cutter) can machine features into outside surface of part A conventional turning center cannot stop workpart at a defined angular position and does not possess rotating tool spindlesA part
Other Machining Operations: Shaping and Planing A single-point tool moves linearly relative to the work partShaping - A tool moves Planing A workpart moves
Stock Turning Milling DrillingOther Machining Operations: Broaching Moves a multiple tooth cutting tool linearly relative to work in direction of tool axisAdvantages:- Good surface finish- Close tolerances- Variety of work shapes possible Cutting tool called a broach- Owing to complicated and often custom-shaped geometry, tooling is expensiveInternal Broaching: Performed on internal surface of a hole A starting hole must be present in the part to insert broach at beginning of stroke
Other Machining Operations: Sawingpower hacksaw linear reciprocating motion of hacksaw blade against workbandsaw (vertical) linear continuous motion of bandsaw bladeDr. M. Medraj Mech. Eng. Dept. - Concordia University Mech 421/6511 lecture 20/17
circular sawDr. M. Medraj Mech. Eng. Dept. - Concordia University Mech 421/6511 lecture 20/18Machinability Machinability A measure of the success of a machining operation usually on a workmaterial. Tool life Force and Power Surface finish Easy of chip disposal Material Removal rate
Next Time:Cutting Tool TechnologyDr. M. Medraj Mech. Eng. Dept. - Concordia University Mech 421/6511 lecture 20/19
Dr. M. Medraj Mech. Eng. Dept. - Concordia University Mech 421/6511 lecture 20/20
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