2. Typical Parts Made with These
Processes
Machine Components
Engine Blocks and Heads
Parts with Complex Shapes
Parts with Close Tolerances
Externally and Internally Threaded Parts
9. Lathe Components
Bed: Usually made of cast iron. Provides a heavy
rigid frame on which all the main components are
mounted.
• Ways: Inner and outer guide railsn that are
precision machined parallel to assure accuracy of
movement.
• Headstock: mounted in a fixed position on the
inner ways, usually at the left end. Using a chuck, it
rotates the work.
• Gearbox: inside the headstock, providing multiple
speeds with a geometric ratio by moving levers.
10. • Spindle: Hole through the headstock to which bar
stock can be fed.
• Chuck: 3-jaw (self centering) or 4-jaw (independent)
to clamp part being machined.
• Tailstock: Fits on the inner ways of the bed and can
slide towards any position the headstock to fit the
length of the work piece. An optional taper turning
attachment would be mounted to it.
• Tailstock Quill: Has a Morse taper to hold a lathe
center, drill bit or other tool.
• Carriage: Moves on the outer ways. Used for
mounting and moving most the cutting tools.
• Cross Slide: Mounted on the traverse slide of the
carriage, and uses a handwheel to feed tools into
the workpiece.
11. • Tool Post: To mount tool holders in which the cutting
bits are clamped.
• Compound Rest: Mounted to the cross slide, it
pivots around the tool post.
• Apron: Attached to the front of the carriage, it has
the mechanism and controls for moving the carriage
and cross slide.
• Feed Rod: Has a keyway, with two reversing pinion
gears, either of which can be meshed with the
mating bevel gear to forward or reverse the carriage
using a clutch.
• Lead Screw: For cutting threads.
• Split Nut: When closed around the lead screw, the
carriage is driven along by direct drive without using
a clutch.
12. • Quick Change Gearbox: Controls the movement of
the carriage using levers.
• Steady Rest: Clamped to the lathe ways, it uses
adjustable fingers to contact the workpiece and align
it. Can be used in place of tailstock to support long
or unstable parts being machined.
• Follow Rest: Bolted to the lathe carriage, it uses
adjustable fingers to bear against the workpiece
opposite the cutting tool to prevent deflection.
13. Lathe Accessories
Carriage and Cross Slide Stops
Devices for Turning Parts with Various Tapers
Milling, Sawing, Gear-Cutting, and Grinding
Attachments
Various Attachments for Boring, Drilling, and
Thread Cutting
23. Things to Remember About
Machining Parts on Lathes
Takes considerable amount of time
High Production Costs
Wastes Material
Not as Economical as Forming or Shaping
31. Jig Boring Machines
Vertical machines
High precision bearings
Used to make jigs and
fixtures
Being replaced by CNC
boring machines
32. Considerations
Through holes, rather than blind holes,
should be specified.
Smaller length-bore diameter ratios
Interrupted internal surfaces should be
avoided.
34. What are Holes used For?
Typical for assembly with fasteners
i.e. screws, bolts, rivets
Weight reduction
Ventilation
Access to inside parts
Appearance
35. Drilling is a Common Process!!!
THE COST OF HOLE MAKING IS AMONG THE
HIGHEST MACHINING COSTS IN
AUTOMOTIVE ENGINE PRODUCTION
36. Properties
Burring on the bottom surface upon
breakthrough requires further machining
Diameters of holes are usually oversize
Quality of drill
Thermal properties
Reaming and honing improve dimensional
accuracy
37. Standard-Point Twist Drill
Point angle (118-135deg)
Lip-relief angle (7-15deg)
Chisel-edge angle (125-135deg)
Helix angle (15-30deg)
Diameter range from 0.5-150mm
38.
39. Other Types of Drills
Step Drill
Produces 2 or more different diameters
Core Drill
Makes an existing hole larger
Counterboring & Countersinking
Produce depressions on the surface to
accommodate the heads of screws/bolts
40.
41. More Drill Types
Center drill
Produces small hole on the
end of a workpiece
Spot drill
Starts a hole at the desired
location
Spade drill
Removable bits, produces
large-diameter or deep
holes
Higher stiffness (absence of
flutes)
Straight-flute drill
Gun drill
45. General Troubleshooting
Problem Probable causes
Drill breakage Dull bit, chips clogging flutes, feed to
high, lip relief angle too small
Excessive drill wear Cutting speed to high, ineffective fluid,
rake angle too high, drill burned when
sharpened
Tapered hole Drill misaligned or bent, lips not equal
Oversize hole Same as above, machine spindle loose,
chisel edge not central, side force on
workpiece
Poor hole surface finish Dull bit, ineffective fluid, welding of
workpiece on drill margin, improperly
ground drill, improper alignment
47. Considerations
Drilling should be perpendicular to the surface
Interrupted holes should be avoided
Hole bottoms should match standard drill point
angles
Through holes preferred to blind holes
Preexisting holes or dimples help center the drill
Blind holes must be drilled deeper than subsequent
reaming or tapping operations
48. What is Reaming
An operation used to make an existing hole
dimensionally more accurate and/or to
improve surface finish
For further accuracy and surface finish, holes
may be burnished, ground or honed.
56. Peripheral Milling
Peripheral Milling is when the cutter is longer than
the width of the cut.
a.k.a.- Slab Milling
The axis of the cutter is usually parallel to the work
piece surface.
57. Face Milling
the cutter is mounted on a spindle having an
axis of rotation perpendicular to the
workpiece surface.
Leaves feed marks on the machined surface.
58. End Milling
The cutter generally rotates on an axis
vertical to the workpiece.
It can be tilted to machine tapered surfaces.
Cutting teeth are located on both the end
face of the cutter and the periphery of the
cutter body.
Can produce a variety of surfaces at any
depth.
64. Design and Operating Guidelines
Basic cutters should be used as much as
possible.
Avoid expensive special cutters.
•Chamfers should be specified instead of
radii.
•Chamfer-A furrow or groove, as in a column.
•Avoid internal cavities and pockets with sharp
corners.
•Due to the difficulty of doing them.
65. Troubleshooting
Tool Breakage Tool material lacks toughness,
improper angles.
Excessive Tool Wear improper tool material, improper
tool fluids.
Rough Surface Finish Feed per tooth too high, tool
chipped or worn.
Chatter Marks Insufficient stiffness of system,
external vibrations.
Breakout Lead angle too low, feed and
depth of cut too high.
69. Bed Type
Work table is mounted is mounted directly on
the bed.
Not versatile
High Stiffness
Used for high production work
70. Other Milling Machines
Planer-Type
Several heads and cutters able to mill different surfaces
•Rotary-Table
•One or more heads for face milling.
•Computer Numerical Control
•Able to mill, drill, bore and tap with repetitive accuracy
•Profile Milling Machines
•5 axes of movement.
71. Planning and Shaping
Planning
Large workpieces 25m X 15m
Work piece is mounted on a table and travels back and
forth along a straight path.
Cutting speeds can get up to 120 m/min with 150 hp
Shaping
Tool does the moving
Small less than 1m X 2m
74. Broaching and Broaching machines
Broaching is a similar
technique to shaping
with a long multiple-
tooth cutter and is used
to machine internal an
external surfaces.
75. Broaching is just as
effective as
Boring
Milling
Shaping
Reaming
76. Broaching machines
are very expensive but
these machines yield a
very high quantity of
production runs.
77. Uses a single pass
for finished shapes
or sized
Produces close
tolerances and good
surface finish
Uses a multipoint
cutting tool (broach)
Has the roughing
and finishing teeth
on the same tool
78. Sawing
Sawing is an old common operation dating back to
around 1000 B.C
Sawing is an efficient bulk removal process and can
produce near net shape materials
The process wastes little material
Most common use of saws
Hacksaws
Circular saws
Band saws
Friction sawing
81. Power hacksaws
Fast
They work smoothly
and efficiently even
under heavy-duty
operation. With normal
care these machines
are indestructible.
82. Circular sawing
Circular sawing is a multipoint cutting process in
which a circular tool is advanced against a stationary
workpiece to sever parts or produce narrow slots.
Uses thin circular blades with teeth on periphery
Rotating blade is fed into a stationary workpiece
Produces a narrow cut and a good surface finish
83.
84. Circular saws also
called cold saws when
cutting metal
They are used for high
production rate sawing
Cold sawing is used in
industry very commonly
particularly for cutting
large crossed sections.
Diamond Saw Blades For Marble
And Limestone
saw blade
for plastics
86. Band saw
Uses a flexible steel band with a toothed edge
Workpieces are fed into the cutting edge on vertical
machines
Can produce straight, irregular, or curved cuts
87. Friction sawing
Workpieces are fed into
a continuously moving
band
Produces fine, accurate
work
Is a finishing operation
in which small amounts
of material are removed
88. Gear Manufacturing by Machining
Several processes for making gears
Form cutting (form-milling)
Gear generating (Hobbing, Shaping)
89. Gear milling
Uses a rotating form
cutter
Gear blanks are
indexed after each cut
Is a low production
process
Gear teeth are
produced individually
90. Gear generating
This particular machine
removes over 17 lb of
8822 steel from a 100-
lb, 18-in.-diameter gear
in under 12 min
91. Gear Hobbing
Is a gear generating
process that uses a
helical hob cutter
Cuts several teeth on a
progressive basis
Is used for high
production runs
92. Gear shaping
Cutters rotate in timed
relationship with the
workpiece
Produces internal
gears, external gears,
and integral gear-pinion
arrangements