TURNING MACHINE

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TURNING MACHINE

• 2 axis (x-z) Machining operations of cylindrical
  and conical parts
• Main parts (See figure for the rest)
• Spindle CW or CCW revolution of material
• Feed Speed of tool meeting the material.
• Tool post The tools are fixed on this part of
  the machine
• Lead screw z axis operations are done by moving
  tool post on this screw
• Cross Slide x axis operations are done by moving
  tool post on this slide.

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TYPES OF LATHES

• ENGINE LATHES (Precision 0.005 typical)
• -General Purpose
• - Manually Controlled
• -Sub Families
• - Toolroom Lathe (called Jewelers lathe)
• - more accurate
• -wider range of speeds and feed
• -smaller, more precise version of engine lathe
• - Gap Lathe
• -Headstock can be removed for unusually large
  diameter to be swung

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• -Wheel Lathe
• -designed to permit the turning of railroad
  cars wheel and axle assemblies
• -Oil Country Lathe
• - have holes through their spindles to permit
  long pieces to be swung.

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Toolroom Lathe
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Gap Lathe
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Wheel Lathe
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Oil Country Lathe
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• TURRET LATHES ( Precision 0.003 typical)
• -Semi-automatic
• -Have multiple tool(usually 6) turret
• -Several things may be happening to the part at
  the same line.

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Turret Lathe
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• CHUCKING MACHINES OR CHUCKERS
• -Automatic
• - Usually vertical
• - Do not have tail stock
• -Used for individual pieces
• - Work-part hold by a chuck
• AUTOMATIC BAR MACHINE(AUTOMATIC SCREW MACHINES) (
  Precision 0.003)
• - Similar to CHUCKERS but workpart hold by a
  collet
• -This way long pieces can be fed through
  headstock.

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• - Automatic
• -Used mostly in screw production that is why it
  is most frequently called automatic screw
  machines.
• - Has two types
• -Single - spindle screw machines (1 tool cuts at
  each time)
• - multiple -spindle screw machines (4-6 tools
  cuts at the same time)
• CNC LATHE
• - Programmable, computer controlled

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Operations Related To Turning

• Facing
• Tool is fed along x axis creates a flat surface
  at the end.
• Taper turning
• Tool is fed at an angle create a conical geometry
• Contour turning
• Instead of feeding the tool along a straight
  line, the tool follows a contour.

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Facing Operation
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Taper Turning
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Contour Turning
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• Form turning
• The tool has a shape that is imparted to the work
  by plunging the tool radially into work.
• Chamfering
• The cutting edge of the tool is used to cut (a)
  an angle on the corner of the cylinder, or (b) at
  the end of the straight turning

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• Cutoff (Parting) or (Necking)
• The tool is fed radially into the rotating work
  at same location.
• (if passes the center than parting)
• Threading (Has a special pointed tool)
• The tool is fed linearly across the outside
  surface of the rotating workpart in a direction
  parallel to the axis of rotation at a large
  effective feed rate, thus creating threads in the
  cylinder.

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Parting (Cut off)
Necking
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Threading
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• Drilling
• Feeding the drill into the rotating work along
  its axis.
• Reaming and Boring
• A single point tool is fed linearly, parallel to
  the axis of rotation, on the inside diameter of
  an existing hole in the part.
• Reaming slightly enlarge a hole.
• Knurling
• This is not a machining operation. Does not
  involve a cutting operation. It is a metal
  forming operation used to produce a regular
  cross-hatched pattern in the work surface.

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Reaming Operation
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Boring Operation
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Drilling Operation
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Knurling Operation
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• Cutting Conditions In Turning
• The rotational speed in turning is related to the
  desired cutting speed at the surface of the
  cylindrical workpiece by equation.
• ?
• N
• p D0
• N rotational speed, rev/min
• ? cutting speed, ft/min (m/min)
• D0 original diameter, ft (m)

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• D0-Df 2d (Df final diameter)
• d depth of cut
• f feed, in/rev (mm/rev)
• fr feed rate, in/min (mm/min) fr Nf
• Tm time to machine from one end of a
  cylindrical workpart to other end. (Actual
  machining) (min)
• L
• Tm
• fr
• L length (mm)

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• ( As a practical matter, a small distance is
  usually added to the length at the beginning and
  end of the workpiece to allow for approach and
  over-travel of the tool, ?L.)
• MRR v.f.d
• Example
• A piece of aluminum is to be cut at 90 m/min.
  Stock totaling 3.2 mm is to be removed, to leave
  a finished surface of 125 mm diameter. The length
  of cut is 100 mm and feed is 0.65 mm/rev. What is
  the cutting time?

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• ? 90 m/min
• Df 125 mm
• 2d 3.2 mm
• L 100 mm add additional 1\16 or 1\4 inches (
  0.75 mm)
• f 0.65 mm/rev
• Tm ?
• L
• Tm where fr N.f
• fr
• ?
• N
• p D0 D0-
  Df 2d
• D0 128.2 mm

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• Methods Of Handling Work In A Lathe
• 4 (1) methods commonly are used to supporting
  work-piece in lathes
• 1. Held between centers
• 2. Held in a chuck
• 3. Held in a collet
• 4. Mounted on a face plate
• 1 Mounted on the carriage
• In the first of 4 of these methods the
  work-piece is rotated during machining. In the
  last (not use extensively) the tool rotates while
  the work-piece is fed in to the tool.

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Chuck
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Collet