Metal Works 2, WASSCE (PC), 2017

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:

(b)α tool steel;
(c)β copper;
(d)γ mild steel.



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:


(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