Milling Machine Operations: Plain or slab milling, Face milling, Angular milling, Straddle milling, Slot and groove milling, Slitting or saw milling, End milling, Gear milling, Form milling Gang milling, Keyway milling, Side milling, Profile milling, Thread milling

Milling Machine Operations

A large variety of components can
be machined on a milling machine which involves various types of operations.
These operations are broadly classified as
follows.

Plain or slab milling, 
Face milling,  
Angular milling,
Straddle milling, 
Slot and groove milling, 
Slitting or saw milling, 
End milling, 
Gear milling, 
Form milling, 
Gang milling, 
Keyway milling, 
Side milling, 
Profile milling,  
Thread milling

1. Plain or slab milling

  Plain milling is used for machining
a flat, plain, horizontal surface, parallel to the axis of cutter with the help
of plain or slab milling cutter.
   For machining of very wide surface,
interlocking teeth plain milling cutters are used instead of simple plain
milling cutters. 
During the operation, the work
piece and cutter ate secured properly on the machine and by rotating the
vertical feed screw of the table and machine, the depth of cut is adjusted.


Plain or slab milling
Plain or slab milling





2. Face milling 



Face milling is employed for
machining a flat surface which is at right angle, to the axis of revolving cutter.
  The cutter used in the process is
face milling type which is rotated about an axis Perpendicular to the work piece.
  The operation is performed on plain
milling machine and depth of cut is
adjusted by rotating the cross feed screw of the table.
  Face mills under 150 mm are called as shell mills
and are held on a short arbor.






Face milling
Face
milling
 

3.  Angular milling

 Angular milling is used for
machining a flat surface at an angle, other than right angle, to the axis of
milling machine spindle. For example, V-blocks. 
According
to the type of surface (single or two mutually inclined), the single or double
angle cutters may be used. 
Angular milling
Angular milling




4.  Form milling

Form milling is the
operation of machining irregular contours by means of form milling cutter.
 The irregular contour may be concave, convex or
of any other shape. 
 The cutting speed of form milling process is 20 – 30
% less than that of the plain milling.
Form milling
Form milling





5.  Straddle milling

 Straddle milling is the operation
of flat vertical surfaces on both the sides of a work piece simultaneously. 
For this purpose two side
milling cutters are mounted on the same arbor.   By using suitable spacing collars, the distance
between the two cutters can be adjusted.
  This process is mainly used for production of square
and hexagonal surfaces.
Straddle milling
Straddle milling



6.  Gang milling 

   Gang milling is the operation of
machining several surfaces of the work piece simultaneously. 
For this, table is fed
against the number of cutters having same or different diameters mounted on a
common arbor.  This method saves machining time and is widely used
in repetitive work.
Gang milling
Gang milling



  7. Slot and groove milling

  slot milling is the operation of producing slots in
solid work pieces.
These slots can be of different shapes such as plain
slots, T-slots, dovetail slots etc. Plain
slot can be milled by using plain milling cutter and end milling cutter.  Groove milling is the operation of
producing grooves of various shapes like plain grooves, curved grooves, v
grooves, etc.
  According to the shape of slot or groove, the cutter
is selected.
    These operations are carried out in two or three stages.  In first stage, open slot is milled by using
suitable cutter (plain milling cutter) and 
then the slot is milled by using special cutters
like T-slot milling cutter. 
Milling a plain slot by end milling cutter
Milling a plain slot by end milling cutter



8. Keyway milling

 
Keyway milling
Keyway milling





Keyway milling is a common operationwhich is performed on milling machine In this a groove is milled on shafts and spindles, which is known as key seat. Fig. shows different types of key seats. awoodruff key seat which is milled with woodruff key seat cutter.  Sunk key seat which is milled with end milling cutter.


9.   Slitting or saw milling

 Saw milling is the operation of
production of narrow slots or grooves on a work piece by using a saw or
slitting milling cutter.
  It is also used for complete parting-off operation. The cutter and work piece are set in such a way that, the cutter is directly placed over one of the T-slots of the table. 
Slitting or saw milling

Slitting or saw milling



10.  Side milling 

  In this operation a side milling
cutter is used for machining a flat vertical surface on one side of the work piece. 
 When two parallel vertical flat
surfaces are required to be machined, then two side milling cutters in pairs
are used.
  By using spacer, the space between two cutters can
be adjusted. 
 Hence, this operation is similar to straddle
milling. 
side milling
side milling



11.  End milling 

This operation is used to machine
and produce a flat surface or a pair of flat surfaces by using an end milling cutter. Fig.  shows the end milling
operation in which flat surface is produced withthe help of an end milling cutter. The surfaces produced may be
horizontal, vertical or inclined with respect to the top of the machine table.
End milling
End milling



12.  Profile milling 

  In profile milling, the profile of
a template or cavity shape of a master-die is duplicated on the work piece
surface. 
  The cutter movement is guided by a tracer control
unit which carries a contact finger.
 This finger runs in contact with
the outline to be duplicated and the tracer mechanism guides the tool accordingly.
profile milling
profile milling



13.  Gear milling

Spur gears are easily produced on plain and universal milling machines for cutting  helical, worm and bevel gears dividing heads are required. (Discussed later in this chapter). Fig shows that, the cutter is
mounted on arbor with its axis at right angle to the work piece. 
Cutter is properly adjusted so that its central line
is radial with the
blank.  The knee is raised to adjust the required depth of
teeth.
  In a single pass, one tooth is finished and table is
returned to its starting position. 
Gear milling
Gear milling


14. Thread milling

  Thread milling is a method of cutting screw threads
with the help of form-milling cutters. 
 Both internal and external threads can be milled.  Thread milling is associated with single or multiple cutters. A single form cutter has a single row of annular
teeth which are lying in one
plane. While cutting, a cutter is tilted
through a helix angle of the thread to avoid interference during cutting.
  During the process, the cutter is
fed radially inward up to the required depth of thread and work piece remains stationary. 
The work piece is held between centers of the machine. Now, the job is rotated slowly and
cutter while rotating is also traversed longitudinally parallel to the work
piece axis with the help of lead
screw. Thread milling is used for cutting coarse threads as
shown in Fig.
Thread milling with multiple teeth cutter (hob) is
as shown in Fig
 The process is almost similar to milling with single cutter. But, the width of the cutter is
slightly more than length of thread produced on the work piece.
Thread milling
Thread milling


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