$($b$)$ Write a CNC part programme using $G$ and $M$ codes for milling a groove $(6$ mm wide $x4mm$

deep$)$ in an aluminium plate as shown in Fig$\mathrm{.}1,$ using a $6$ mm end mill cutter. Also, there are $3$

holes $(6)$ to be drilled as shown. $Z=0$ at $100$ above top surface of the work piece and

thickness of the work piece is $25$ mm $.$

Fig. $1$