school work

1. Cutting Speed and Feed

2. Cutting speed
Cutting speed for drilling is the rate at which the tool
passes over the surface of the metal. i.e how fast the
cutting tool is spinning . It is commonly expressed in
metres per minute.

3. Cutting speeds depend on:
The material being cut
Condition and strength of the tool and machine
Depth of cut
Rate of feed
Material of which the tool is made
Availability of cutting fluid
Size of the bit being used

4. Cutting speed selection
The softer the work material, the faster the
recommended cutting speed

5. The hardness of the cutting tool material has a
great deal to do with the recommended cutting
speed. The harder the cutting tool material, the
faster the cutting speed. The softer the cutting
tool material, the slower the recommended
cutting speed

6. Calculating cutting speed
Given in metres per minute
spindle speed of machine (N) and diameter of
work must be known
S (m/min)= πDN/1000
Where π= 22/7 or 3.142
 D= diameter of material
 N= Spindle speed(rev/min)
47-6

7. Spindle Speed
The rate at which the spindle rotates. It is commonly
expressed in revolution per minute.

8. Calculating Spindle speed
(rev/min)
D
xS1000
rev/min
π
=
S (m/min)= cutting speed
Where π= 22/7 or 3.142
D= diameter of material
N= Spindle speed(rev/min

9. Examples
Calculate rev/min required to drill a hole 15mm
diameter in a piece of machine steel (CS 90)
Find the cutting speed of a 10mm diameter drill with
a spindle of 178 rev/min.

10. 5. Find the cutting speed for:
 Diameter 9mm. Spindle speed 180rev/min
 Diameter 6mm. spindle speed 20rev/min
 Diameter 5mm. spindle speed 160rev/min
 spindle speed 120 rev/min. Diameter 10mm.
6. Find the spindle speed for:
 Diameter 16mm. Surface speed 20 m/min
 Diameter 14mm. Surface speed 30 m/min
 Diameter 15mm. Surface speed 15 m/min.

11. Feed
Feed rate is the velocity at which the drill bit is fed,
that is, advanced into the work piece.

12. Feed rate is dependent on the:
Type /size of the tool
 Surface finish desired
Power available at the spindle
 Rigidity of the machine and tooling setup
 Strength of the work piece set up
 Characteristics of the material being cut, chip
flow depends on material type and feed rate.
Depth of cut