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Considering that the workpiece rotates in turning and the drill rotates in drilling, feed per revolution and cutting speed for drilling can be found in a similar way to turning. When the drill moves 100mm in a minute at 1,000 RPM, feed per minute is vf=100mm/min.
Drilling time (tc)
Drilling time is the time required to drill.
The denominator in the above formula is spindle feed. The numerator in the above formula is ℓd (hole depth) x i (number of holes), total drilling length. Spindle feed is the amount of movement of the drill per minute. Therefore, drilling will be complete when the drill has moved the total drilling length.
Tc (min):
n (minˉ¹):
ℓd (mm):
fr (mm/rev):
i:
Drilling time
Spindle speed (RPM)
Hole depth
Feed per revolution
Number of holes
Drilling five 30mm length holes. When spindle speed is 1,350minˉ¹ and feed per revolution is 0.2mm/rev,
(30x5)÷(1,350x0.2)=0.555<br>0.555x60=33.3
Drilling time is about 33.3 seconds.
Reference:
Example:
Feed of the main spindle (vf)
Feed of the main spindle is the amount of movement of the drill per minute.<br>Feed of the main spindle (Z axis) is fr (feed per revolution) x n (RPM), the amount of movement of the drill per minute.
vf = fr x n (mm/min
vf (mm/min):
fr (mm/rev):
n (minˉ¹):
Feed speed of the main spindle (Z axis)
Feed per revolution
Rotational speed of the main spindle (RPM)
Example:
When feed per revolution is 0.2mm/rev and main spindle speed is 1.350 minˉ¹, 0.2 x 1,350 = 270
The spindle feed is 270 mm/min.
Reference:
Cutting speed (vc)
Cutting speed when drilling is the peripheral speed of the drill; metres the drill
moves in a minute. It be calculated by a similar formula to turning’s.
(πD) of the above formula is the periphery of the drill.
The periphery x n (RPM) is the amount of movement of the drill’s outer corner per minute (mm). Usually expressed in m/min. Divide by 1,000 to change to m from mm.
vc (m/min):
D1 mm:
π (3.14):
n (minˉ¹):
Cutting speed
Drill diameter
Circular constant
Rotational speed of the main spindle (RPM)
Reference:
x
Distance that tool moves in a minute
Diameter 10 mm
fr=0,1 mm/rev
Feed per revolution
fr=100/1,000=0,1 mm/rev
Cutting speed
vc=πDN/1,000
=3.14x10x1,000/1,000
=31.4m/min