Question 2
(a)(i) Sketch a micrometer screw gauge.
(ii) Label any three parts.
(b)(i) State three functions of coolants.
(ii) List one cutting lubricant used when drilling each of the following:
(a)metals:
(b)α tool steel;
(c)β copper;
(d)γ mild steel.
Observation
The question was well attempted by the candidates except for few of them who sketched G-clamp instead of micrometer screw gauge. The required responses to this question are as follows:
2(a)(i)
(b)(i) Functions of coolant
- It cools the workpiece.
- It cools the tool bit.
- It reduces power consumption.
- It prevents welding of chips to tools.
- It washes away swarf and chips.
- It prolongs the life span of the tool.
(ii) Cutting lubricants when drilling
α tool steel: soluble oil, lard oil with sulphur
β copper: soluble oil
γ mild steel: soluble oil/lard