Milling Processes
Objective
s
The students are able to
identify:
Various Types of Milling Machine
& Layout
Industrial Applications
Milling Tools
Operation Factors - Speed,
Feed, ...
Milling Methods
Planning & Setup Procedures
Practices
Classification of Machining
Processes
Milling
Process
Milling is a machining
operation in which a
workpiece is fed past
a rotating cylindrical
tool with multiple
cutting edge. Cutting
Multi-points cutting Direction
Tooth
process
Chips are cut off
by the rotating Milling
cutter
Cutter
Workpiece is fed in Workpiece
linear motion
Tool with one cutting Feed Direction
Basic Milling
Processes
Two types of milling processes
Up milling or conventional
milling process
Down milling or Climb milling
process
Up Milling (Conventional Milling)
The metal is removed in form of small chips
The chip thickness is minimum at the start of the cut and
maximum at the end.
Cutting force varies from zero to the maximum value
Advantages of Up Milling
It does not require backlash eliminator
It is safer in operation ( the cutter does not climb on the
workpiece)
Loads on the teeth are acting gradually
Built-up-edge (BUE) fragments are absent from the machined
surface
The cutter is not affected by the sandy surfaces of the workpiece
Disadvantage of Up Milling
The tendency of cutting force to lift the work piece from the
fixtures and
poor surface finish obtained
Up Cut
FEED
Up Cut
FEED
Up Cut
FEED
Up Cut
FEED
Up Cut
FEED
Up Cut
FEED
Up Cut
FEED
Up Cut
FEED
Up Cut
FEED
Up Cut
FEED
Up Cut
FEED
Up Cut
Cutter rotates
in a direction
opposite to
the table feed
CUTTER
FEED
Down Milling (Climb Milling)
A cutter rotating in the same directions of the feed of the workpiece.
Chip thickness is maximum at the start of the cut and minimum in the end.
There is less friction involved and consequently less heat is generated on the
contact surface of the cutter and workpiece
Advantages
Fixtures are simpler and less costly, as cutting forces are acting downward
Flat workpiece (that cannot be firmly held) can be machined by down-milling
Cutter with higher rake angles can be used, which decreases the power requirements
Tool blunting is less likely
Better surface finish
It is characterized by less tendencies of chattering and vibration
Down Cut
FEED
Down Cut
FEED
Down Cut
FEED
Down Cut
FEED
Down Cut
FEED
Down Cut
FEED
Down Cut
FEED
Down Cut
FEED
Down Cut
FEED
Down Cut
FEED
Down Cut
FEED
Down Cut
Cutter rotates
in the same
direction as
the table feed
FEED
CUTTER
Up Cut Vs Down Cut
Up Cutting Down Cutting
Will not cause Better surface
the table to a finishing
step motion Not suitable for
Recommended conventional
for machine
conventional Suitable for CNC
machine machine or the
machine equipped
with BACKLASH
ELIMINATOR
Types of Milling Cutters
Type of Milling Cutter
Type of Milling
Operations
Two basic type of
milling operations
Peripheral milling
(Plain Milling)
Axisof the tool is parallel
to the surface being
machined.
Face milling
Example of Peripheral
Milling
(a) Slab milling; (b) Slot Milling; (c) Side
Milling (d) Straddle Milling (e) Form Milling
Peripheral Milling
Direction of Cutter Rotation
Two form of milling
Up milling and down milling
Up milling (Conventional milling): the direction of motion
of the cutter teeth is opposite the feed direction when
teeth cut into the workpiece.
It is milling “ against the feed”
Down Milling (Climb Milling): the direction of cutter
motion is the same as the feed direction when teeth cut
into the workpiece.
It is milling “ with the feed”
Face Milling
The axis of the cutter is perpendicular the surface being
milled.
Various forms of face milling
(a) Conventional face milling; (b) Partial face milling; (c) End
Milling; (d) Profile Milling;
(e) Pocket Milling; (f) surface contouring Milling
Milling
Method End
• Plain Milling
– Cutter axis parallel Milling
Cutter axis perpendicular
to the
to the machined
machined surface
surface
Peripheral & end
– Peripheral cutting
cutting edges
edges
Vertical milling
– Horizontal milling normally
normally
PLAIN MILLING END MILLING
Milling Machines
It has a horizontal spindle and well suited for
performing the peripheral milling (e.g. slab
milling, slotting milling, side milling and
straddle milling)
It has a vertical spindle and well suited for
performing the face milling (e.g. end
milling, surface contouring milling)
Horizontal Milling Machine
Spindle arbor rotates
to the table
parallel
Machine table moves
along the 3 axes - X,Y,
&Z x
Cutter being used:
y
Slab milling cutter
Side & face cutter
z
Slitting saw
Cutters for Horizontal Milling
Machine
SLITTING SAW
SLAB MILLING CUTTER
SIDE & FACE CUTTER
Vertical Milling
Machine
Spindle rotates
perpendicular to the
table normally
Milling Head can be
adjusted in different
angle
Cutter being used :
End mill
Face milling cutter
Cutters for Vertical Milling
Machine
END MILL FACE MILLING CUTTER
Type of Milling Machines
Special purposes milling
machine
Knee and Column Milling Machine
Planer Type Milling Machine
Rotary Table Milling Machine
Tool
Material
High Speed Steel
An alloy of iron, chromium, nickel, cobalt & some
molybdenum etc..
High resistance to wear, loss hardness at
600°C
Two basic types:
Tungsten –type (T-grades by AISI)
Molybdenum –type (M-grades by AISI)
Carbide
Widely apply in modern industry
Suitable for very higher cutting speed, hard material, &
high accuracy
Smooth surface
Ceramic & Diamond cuttingtool
Cutting
Speed
Cutting Speed of milling is defined by the
movement of each cutting edge per
minute
(m/min)
TOOL HIGH SPEED
CARBIDE
MATERIA STEEL
L
Cutting Cutting
Speed Feed Speed Feed
MATERIAL mm/Tooth mm/Toot
m / min. m / min.
h
MILD STEEL 25 0.08 100 0.15
ALUMINUM 100 0.15 500 0.3
HARDEN STEEL 50 0.1
Cutting Fluid
Cooling the workpiece &
the cutting tool
Maintain hardnessof
cutting tool
Provide
lubrication
Reduce
fraction
between
workpiece
&
cutting tool
Washaway the
chips
Prolong tool
SAFETY
Consult Staff Where are the Dangerous
Points
Familiar with the Controls
Stop the Machine in Emergency
Only One Man Operates One Machine
Suitable & Safety Protection of Yourself
Don't Leave the Machine when it is
Running
Don't Touch the Work while it is Running
Don't Operate the Machine Without Staff
Supervised
End
