Estimate milling time for the initial machining operation.

The blank Hastelloy$-$X plates used to make the injector plate come from the supplier in dimensions of $360$mm x $360$mm x

$32$mm $($thickness$)$ with a rough surface finish on both the top and bottom surfaces resulting from the plate rolling operation

used for their manufacture. As such, before the machining of any features can be done, the plates will need their top and

bottom surfaces machined in order to improve their surface finish and reduced the plate thickness to the desired $28$mm$.$ This

machining operation will be done by face milling on a vertical mill. The face milling cutting tool has $8$ teeth, a diameter of $85$

mm$.$ The maximum depth of possible with the cutting tool is $1$mm$.$ The cutting speed is $89\mathrm{.}5716$ m$/$min$,$ the feed $($chip load$)$

is $0\mathrm{.}51$ mm$/$tooth$.$ Determine the total machining time required for the operation assuming that there is a $20\%$ overlap of

adjacent tool passes i$.$e$.20\%$ width of the tool cover the area machined by a previous tool pass. Neglect any time for

repositioning of the workpiece or cutting tool