Manufacturing Various Shapes

							 Manufacturing
Various Shapes

  Manufacturing
   Processes
          Outline

Milling
  Slab Milling
  Face Milling
  End Milling
  Other
Broaching
Sawing
Machining Gears
    Milling – Types
       of Milling
Slab Milling
Face Milling
End Milling
Various Special Operations
Various Milling Tools
 Action of a
Milling Cutter
Conventional Milling
 and Climb Milling
         Slab Milling




Axis of tool rotation is parallel to
 the workpiece surface

Cutters may have straight or
 helical teeth
Slab Milling
   Tools
Slab Milling
   Tools
        Face Milling




Axis of cutter rotation is
 perpendicular to the workpiece
 surface

Leaves feed marks that vary with
  the feed rate
Face Milling
   Tools
         End Milling




Axis of cutter rotation is usually
 perpendicular to the workpiece
 surface

Ball mill cutters have
 hemispherical ends and can be
 used to mill curved surfaces
End Milling
  Tools
End Milling
  Tools
         End Milling
           Tools




(left to right) roughing end mill, center-
           cut end mill, ball mill.
 Center-cut end mills can be fed into
      the workpiece like a drill.
          End Milling
            Tools




Close-up view of a roughing end mill (left) and a
           center-cut end mill (right)

                         Result of using a non-
                         center-cut end mill while
                         feeding into the
                         workpiece; the center
                         has been clogged with
                         wood. A metal workpiece
                         would cause the tool to
                         shatter.
End Milling
Freeform Surfaces




Example of a surface that can be milled
with a computer-controlled ball mill
Milling Freeform
    Surfaces
Milling and Feed Marks
Milling and Feed Marks




  The difference in feed marks between a larger
   cutting increment (left) and a smaller cutting
                 increment (right).
   Other Milling
Operations and Tools
   Other Milling
Operations and Tools
   Other Milling
Operations and Tools
   Other Milling
Operations and Tools
   Other Milling
Operations and Tools
           Milling Feed
           and Speed
                  V = πDN

V = Cutting speed, ft/min or m/min
D = Cutter Diameter
N = RPM of the cutter

                  f= v/Nn

f = Feed, in/tooth or mm/tooth
v = Linear speed of the workpiece into the
   cutter
N = RPM of the cutter
n = Number of teeth on the cutter edge

Make sure to account for unit differences.
Milling Feed
and Speed
             Milling Feed
             and Speed
Example:
Workpiece Material: titanium alloy
Cutter Diameter: 3 in.
Cutting Teeth: 10
Conditions: general

V(titanium, general) = 175-200 ft/min (from table) =
   2100-2400 in/min

                      N = V/πD
                N = (2100-2400)/(π*3)
                   = 223-255 RPM

f(titanium, general) = .005-.006 in/tooth (from table)

                       v = Nnf
                v = 223*10*(.005-.006)
                  = 11.2-13.4 in/min
      Milling Material
      Removal Rate
           MRR = wdv

w = Width of the cut
d = Depth of the cut
v = Linear speed of the
  workpiece into the cutter
     Milling Material
     Removal Rate
Example:
Cut Width: 4 in
Cut depth: .2 in
Workpiece Speed: 11.2 in/min

         MRR = wdv
       MRR = 4*.2*11.2
        = 8.96 in3/min
          Milling in
          General
Design Considerations:
- Use standard milling cutters;
  avoid expensive special cutters
- Use chamfers instead of radii
  (fillets)
- Avoid internal cavities and
  pockets with sharp corners
- Use materials rigid enough to
  minimize clamping and cutting
  deflections
           Milling in
           General
Avoiding Vibration and Chatter:
- Mount cutters close to the
  spindle base to reduce tool
  deflection
- Use rigid tool holders and
  fixtures
- If vibration and chatter occur,
  change the tool shape and use
  cutters with fewer cutting teeth
  or random tooth spacing
         Broaching

Used to machine internal and
 external surfaces of varying
 shapes

Produces parts with fine surface
  finish and dimensional
  accuracy
Broaching Machine
Broaching Machine
Cutting Action
 of a Broach
Broaches
         Broaching

Design Considerations:
- Design parts so that they can
  be clamped securely in
  broaching machines and
  withstand cutting forces

- Avoid blind holes, sharp
  corners, dovetail splines and
  large flat surfaces
- Use chamfers instead of round
  corners when possible
           Sawing

Used to separate large pieces of
 material by removing the
 connecting material

Wastes little material because
 the width of the cut is thin
Sawing
     Machining Gears

Gears are cut from gear blanks
 (disks)

The following may be used to cut
  gear teeth:
- A form cutter
- Broaches (often for internal teeth)
- A single-point cutting tool guided by
  a template
- A pinion-shaped cutter
- A rack-shaped cutter
- A hob
Machining Gears
Machining Gears
         Summary

Many types of complicated and
 irregular shapes can be
 created by milling, broaching
 and sawing

Gears can be shaped by these
 and similar means