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MET 33800 Manufacturing Processes
Chapter 22
Turning and Boring Processes
Chapter 22 ‐ 1
Materials Processing
Chapters 15-17
Chapters 30-33
Chapters 20-27
Chapters 11-13
Chapter 22 ‐ 2
Page 268 Figure 11‐1, The Five materials processing families with subgroups and typical processes
Turning Processes Turning: machining external cylindrical surfaces.
Taper Turning: machining external conical surfaces.
Chapter 22 ‐ 3
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EXTERNAL PROCESSES1. Straight Turning
2. Taper Turning
3. Facing
4. Trepanning/Face Grooving
5. Contour Turning
6. Form Turning
7. Cutoff
8. Grooving/Necking
9. Threading
10.KnurlingChapter 22 ‐ 4
INTERNAL PROCESSES1. Boring
2. Taper Boring
3. Forming
4. Drilling
5. Reaming
6. Threading
7. Tapping
Chapter 22 ‐ 5
STRAIGHT TURNING Machining cylindrical surfaces:
Tool motion parallel to axis of rotation.
Roughing cuts through hard surface.
Cut right to left cutting force toward workholding device.
Chapter 22 ‐ 6
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STRAIGHT TURNINGMachining cylindrical surfaces (continued):
Finishing cuts for size and surface finish.
Multiple finishing cuts to offset tool/part deflection.
Cutting Speed (V) Relates velocity of rotating workpiece to stationary tool (sfpm).
Tool set to spindle centerline or slightly above to reduce part climbing.
Chapter 22 ‐ 7
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STRAIGHT TURNINGMachining cylindrical surfaces (continued):
Feed (fr) Amount of material removed per revolution or pass of the tool (ipr).
Depth of Cut initial diameter D1 and final diameter D2.
D - D1 2d = 2
Chapter 22 ‐ 8
STRAIGHT TURNING
Spindle Speed (Ns)
Material Removal Rate (MRR)
Cutting Time (TM)
D N1 sV = 12
2 21 2
1
D - DM R R =12 V f 12 V f dr r4D
ML + A
T = f Nr s
Chapter 22 ‐ 9
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TAPER TURNING
Machining conical surfaces:
Compound Rest 1min; short tapers only; steep tapers possible.
Setting over Tailstock Part between centers.
Taper Attachment Guide bar set to angle. Guide shoe moves cross slide transverse while saddle move longitudinally.
CNC Machines chapter 40
Form tools required angle ground into the tool
Chapter 22 ‐ 10
Chapter 22 ‐ 11
TAPER TURNING
TAPER TURNING
Chapter 22 ‐ 12
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TAPER TURNING
Chapter 22 ‐ 13
FACINGMachining flat surfaces with tool motion 90 to axis of rotation:
Spindle speed based on largest diameter.
Cutting direction can be either way ‐ controlled by tool shape.
Chapter 22 ‐ 14
Tool must be set at spindle centerline.
Saddle is clamped to prevent cutting force causing longitudinal motion.
Material Removal Rate
Cutting Time
MRR =6 V f dr
ML + A
T = f Nr s
FACING
Chapter 22 ‐ 15
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NECKING(Grooving or Partial Cutoff)
Forming grooves which are not to spindle c’line:
Must minimize overhang of tool and maximize tool size.
Grooving Tool Configurations
Chapter 22 ‐ 16
FACE GROOVING(Trepanning)
Chapter 22 ‐ 17
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CUTOFF (PARTING)Cut to centerline to separate work from bar :
Cut typically not accurate cannot be used for back facing.
Tool must be set at spindle centerline.
Tools thin w/large overhang.
Chapter 22 ‐ 18
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FORM TURNINGShape of surface controlled by tool form:
Form Cutting Tool is mirror image of desired shape.
Skiving Tool move tangentially across workpiece. Improved finish and accuracy.
Chapter 22 ‐ 19
THREADING Standard and special form screw threads:
Single Point Generating thread form.
Self‐Opening Die Heads Multiple point cutters.
Chapter 22 ‐ 20
KNURLINGRegularly shaped, roughened surface:
Chipless, cold forming process.
High transverse forces.
Chapter 22 ‐ 21
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DRILLINGGenerate or enlarge holes on centerline: Drill mounted in tailstock quill (Morse taper), Jacobs chuck
or using tailstock center and driver.
Hand feed with tailstock handwheel.
Chapter 22 ‐ 22
PRECISION BORINGBoring enlarges existing holes:
Produces cylindrical shapes (exception: bell‐mouth).
Produces concentric shapes to centerline.
Tool mounted on cross slide and set at centerline of spindle.
Critical to minimize overhang and maximize boring
tool size.
Chapter 22 ‐ 23
PRECISION BORING
Chapter 22 ‐ 24
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PRECISION BORINGPiloted boring tool:
Allows larger diameters to be bored on a lathe.
Increases support of tool – minimized deflection.
Improves bore geometry.
Chapter 22 ‐ 25
TAPER BORING
Machining conical internal surfaces:
Compound Rest 1minimum; short tapers only; steep tapers possible.
Taper Attachment Guide bar set to angle. Guide shoe moves cross slide transverse while saddle move longitudinally.
CNC Machines chapter 40.
Form tools can be used.
Chapter 22 ‐ 26
REAMING Enlarge existing bores:
Used for accuracy and surface finish:
Reamer held using same methods as a drill.
Floating holders required for larger sizes.
Hand feed with tailstock handwheel.
Chapter 22 ‐ 27
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INTERNAL THREADSInternal threads can be cut or generated:
Tapping head with reversing capability.
Collapsible taps similar to geometric die heads.
Single point thread generation.
Chapter 22 ‐ 28
DIMENSIONAL ACCURACYPrecision (repeatability) influenced by:
Deflection due to cutting forces.
Workpiece characteristics:
Material, shape and rigidity.
Tool characteristics:
Material, shape and rigidity.
Tool wear and built‐up edge.
Workholding characteristics:
Strength and rigidity.
Chapter 22 ‐ 29
Chapter 22 ‐ 30
DIMENSIONAL ACCURACY
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Surface Roughness
Where: CR = tool nose (corner) radius
2 2 2r rCR - f f
y = CR - 4 8CR
Chapter 22 ‐ 31
DIMENSIONAL ACCURACY
2 2 2r rCR - f f
y = CR - 4 8CR
Chapter 22 ‐ 32
DIMENSIONAL ACCURACY
LATHE SIZE DESIGNATIONS SwingMaximum diameter over bed. Cross slide reduces
swing.
Distance between centersMaximum length. Spindle thru‐diameter allows longer stock.
Chapter 22 ‐ 33
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LATHE DESIGN
Chapter 22 ‐ 34
LATHE DESIGN
Chapter 22 ‐ 35
LATHE DESIGN
Chapter 22 ‐ 36
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LATHE TYPES1. Engine Lathe Headstock, carriage (saddle) assembly and
tailstock.
Chapter 22 ‐ 37
LATHE TYPES2. Speed Lathe Headstock, tailstock and simple tool post.
Chapter 22 ‐ 38
LATHE TYPES3. Toolroom Lathe Engine lathe with higher accuracy.
Chapter 22 ‐ 39
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LATHE TYPES4. Gap‐bed Lathe Gap in the bed, removable bed section or
sliding beds allow greater swing capability.
Chapter 22 ‐ 40
TURRET LATHE VARIATIONS
Chapter 22 ‐ 41
TURRET LATHES5. Saddle‐type Turret Lathe Turret mounted on saddle.
Chapter 22 ‐ 42
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6. Ram‐type Turret Lathe Ram and turret moved with capstan wheel.
TURRET LATHES
Chapter 22 ‐ 43
TURRET LATHES
Chapter 22 ‐ 44
TURRET LATHES7. Vertical Turret Lathe Large parts.
Chapter 22 ‐ 45
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AUTOMATIC LATHE TYPES8. Single‐Spindle Screw Machine Automatic lathe w/turret
mounted in vertical plane.
9. Multiple‐Spindle Screw Machine All tools cut simultaneously.
10. Swiss‐type Screw Machine Tools on radial slides.
11. Automatic Lathe Simultaneous cuts with massed tooling.
12. Computer Numerically Controlled Lathe Incorporate microprocessor control.
Chapter 22 ‐ 46
AUTOMATIC LATHE TYPES
Single Spindle Automatic – one tool cuts at a time.
Chapter 22 ‐ 47
AUTOMATIC LATHE TYPES
Chapter 22 ‐ 48
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AUTOMATIC LATHE TYPES
Chapter 22 ‐ 49
AUTOMATIC LATHE TYPES
Chapter 22 ‐ 50
AUTOMATIC LATHE TYPES
Chapter 22 ‐ 51
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AUTOMATIC LATHE TYPES
Chapter 22 ‐ 52
AUTOMATIC LATHE TYPES
Chapter 22 ‐ 53
Swiss Type Automatic
AUTOMATIC LATHE TYPES
Chapter 22 ‐ 54
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1. Milling Attachment Part on cross slide, tool in spindle.
2. Tool‐Post Grinder Mounted on cross slide.
SPECIAL LATHE ATTACHMENTS
Chapter 22 ‐ 55
SPECIAL LATHE ATTACHMENTS
Chapter 22 ‐ 56
3. Duplicating Attachments Uses templates for complex shapes.
CUTTING TOOLS and HOLDERS
Chapter 22 ‐ 57
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LATHE WORKHOLDING METHODS
Chapter 22 ‐ 58
1. Centers long parts; limits internal work
Live and dead 60 centers.
Lathe dog used with a dog plate or faceplate.
LATHE WORKHOLDING METHODS
Chapter 22 ‐ 59
LATHE WORKHOLDING METHODS
Chapter 22 ‐ 60
Face Driver used with center.
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Mandrels Solid, gang, cone, or hydraulic.
LATHE WORKHOLDING METHODS
Chapter 22 ‐ 61
2. Chucks flexible ‐ grip inside or outside
Spiral cam w/chuck wrench or drawbar
Two‐jaw small work
Three‐jaw simultaneous jaw motion
Four‐jaw independent independent jaw motion
Four‐jaw combination both independent and simultaneous
LATHE WORKHOLDING METHODS
Chapter 22 ‐ 62
LATHE WORKHOLDING METHODS
Chapter 22 ‐ 63
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Hydraulically actuated with draw tube.
LATHE WORKHOLDING METHODS
Chapter 22 ‐ 64
3. Collets high accuracy:
Split w/taper; internal/external; multiple shapes
Drawback can be a problem.
LATHE WORKHOLDING METHODS
Chapter 22 ‐ 65
LATHE WORKHOLDING METHODS
Chapter 22 ‐ 66
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LATHE WORKHOLDING METHODS
Chapter 22 ‐ 67
LATHE WORKHOLDING METHODS
Chapter 22 ‐ 68
LATHE WORKHOLDING METHODS
Chapter 22 ‐ 69
4. Faceplates parts or fixtures clamped in place:
Can be used with center and drive dog.
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5. Follow Rests Mounted on saddle. Two support fingers/ rollers behind tool.
6. Steady Rests Clamped to ways. Three support fingers/ rollers.
WORKHOLDING/SUPPORT ATTACHMENTS
Chapter 22 ‐ 70
WORKHOLDING/SUPPORT ATTACHMENTS
Chapter 22 ‐ 71
Follow Rest
Steady Rest
WORKHOLDING/SUPPORT ATTACHMENTS
Chapter 22 ‐ 72
Steady Rests
Follow Rest
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The End – See Oncourse for Videos
Chapter 22 ‐ 73
