Drilling PDF
Drilling PDF
Drilling PDF
OPERATIONS
INTRODUCTION
Base
DRILLING OPERATION
Drill
Workpiece Length of
approach
Thickness of
workpiece, L
Length of recess
or overtravel
DRILLING OPERATION
PURPOSE OF LENGTH OF
APPROACH AND OVERTRAVEL
120° to 135°
Cutting edges or lips
Chisel edge
MRR IN DRILLING OPERATION
MRR = (╥ D^2 / 4) f N
mm^3/min
MACHINING TIME
Drill
Workpiece Length of
approach
Thickness of
workpiece, L
Length of recess
or overtravel
MACHINING TIME
MACHINING TIME IS GIVEN BY
t= L / fN min
Where L is in mm
f is in mm/rev
N is in rpm
BORING
To ensure correct location of a
hole by making it concentric with the
axis of rotation
Desired final
Adjustment cylindrical
surface
for depth of cut
BORING OPERATION
C r o s s R a il
T ool H ead
W o r k P ie c e
W o rk T a b le
B ed
C o lu m n
REAMING
R eam er
W orkpiece
To produce more accurate holes, the
sequence of operations will be
CENTERING
DRILLING
BORING
REAMING
TAPPING
Tap
Workpiece
TAPPING PROCESS
IT IS A FORMING PROCESS
Counterbore
CARRIED TO PROVIDE
SEATING FOR HEAD OF
SCREW, USING
COUNTERSINK TOOL
EXAMPLES
For turning and facing operations, rpm is 250 and for drilling
rpm of the cutter are 200. Drilling operation is carried out
on a drilling machine. Assume 2 passes for turning
operation and 5 passes for facing operation. Assume feed of
0.5 mm/rev. for all operations. For drilling assume
approach and over travel distance as 20 mm. Calculate
2 0 d ia
52
100
EXAMPLES
Solution: For determining processing time for components
requiring more than one operation, always first determine
the best possible sequence for manufacturing the
component. To manufacture component shown in Figure
6.9, which requires three operations – facing, drilling and
turning – any of the following sequences can be used
(a) Facing (b) Turning (c) Drilling
(a) Turning (b) Facing (c) Drilling
(a) Drilling (b) Turning (c) Facing
(a) Drilling (b) Facing (c) Turning
The total time required to manufacture the component
would be the sum of all individual operations.
Now, let us consider the first sequence, i.e. facing, turning
and drilling and compute the time required to complete the
job.
EXAMPLES
Total time:
Total processing time/component = Tfacing +
Tturning + Tdrilling
= 1.2 + 1.6 + 1.2
= 4 minutes.
EXAMPLES
Manufacturing time:
Manufacturing time/component = Processing
time + setup time
= 4 + 0.25 × 4
= 5 minutes
Total time for producing 1000 components (T):
T = 5 × 1000 = 5000 minutes
Number of components
that can be produced in one year:
The company works 8 hr/day and 300 days in
a year.
Total working time = 8 × 300 = 2400 hrs.
Number of components produced in this
period = 2400×60/5
= 28000 pieces
EXAMPLES
Alternate sequence of operations:
If the component is manufactured by the
process sequence – drilling, turning and facing.
Using the above procedure, we get
Tdrilling = 130 / (0.5×200) = 1.3 minutes
Tturning = [110 / (0.5×250)]×2 = 1.76 minutes
Since, drilling and turning operations are
already done on workpiece, length of tool travel
for facing would be
l = (52-20) / 2 = 16 mm
Tfacing = [16 / (0.5×250)]×5 = 0.64 minutes
Ttotal = 1.3 + 1.76 + 0.64
= 3.7 minutes
EXAMPLES
Manufacturing time = 3.7 + 0.25×3.7
= 4.625 minutes
Total time for producing 1000 components
= 4625 minutes