An eight$-$station rotary indexing machine with no internal storage performs the machining operations shown in Table $4\mathrm{.}0,$ with processing times and breakdown frequencies for each station. Transfer time is $0\mathrm{.}15$min. A study of the system was undertaken, during which time $2,000$ parts were completed. The study also revealed that when breakdowns occur, the average downtime is $70$ minutes.

Table $4\mathrm{.}0$: Rotary Index Machine Study Results

Station Process Process time Breakdowns

$1$ Load part $0\mathrm{.}50$ min $0$

$2$ Mill OD $1\mathrm{.}55$ min $22$

$3$ Mill steps $0\mathrm{.}10$ min $31$

$4$ Drill two holes $0\mathrm{.}60$ min $47$

$5$ Drill six holes $0\mathrm{.}45$ min $8$

$6$ Ream two holes $0\mathrm{.}92$ min $88$

$7$ Tap six holes $0\mathrm{.}75$ min $54$

$8$ Unload part $0\mathrm{.}40$ min $0$

Note: Transfer Line formulae are available in the Formula Sheet