Unit 13: Mechanical Operations
LO4: Be able to use drilling and milling machines to
produce quality components
Speeds and feeds
Instructions and answers for teachers
These instructions should accompany the OCR resource ‘Speeds and feeds’ activity which supports
Cambridge Technicals in Engineering Level 3.
The Activity:
This activity offers an
This activity offers an
opportunity for English
opportunity for maths
skills development.
skills development.
!
Suggested
timings:
1 hour
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!
Activity 1: Cutting Conditions calculation
Solutions to the problems are shown below. Learners may need some guidance with the correct
selection and use of the formulae. Teachers could develop further problems involving speed and feed
rates for learners to solve.
a) Cutting speed can be calculated using the following equation:
𝑣𝑐 =
𝜋×𝐷×𝑛 𝑚
(
)
1000
𝑚𝑖𝑛
where:
𝐷 =13mm
𝑛 =1400 rev/min
hence vc = 57.2 m/min
b) The feed rate of the spindle can be calculated using the following equation:
𝑣𝑓 = 𝑓 × 𝑛
where:
𝑓 = 0.2 mm/rev
𝑛 = 1200 rev/min
hence vf = 0.2 * 1200 = 240 (mm/min)
c) The drilling time can be calculated from the following equation:
𝑇𝑐 =
where:
𝑙𝑑 = 30mm
𝑓𝑟 = 0.15mm/rev
hence Tc = 11.3 s
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𝑙𝑑
𝑛 × 𝑓𝑟 × 60
Spindle speed can be calculated using the following equation:
𝑛 = 𝑣𝑐 × 𝜋𝐷
where
𝑣𝑐 = 50m/min
𝐷=15mm
Activity 2: Drilling operated processes
Solution to the problem is shown below:
Version 1
Tapping
B
Centering
E
Spotfacing
F
Countersinking
D
Reaming
A
Counterboring
C
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