TABLE OF CONTENTS When every second counts for bottom-line economics it is important to think in terms of saving minutes or seconds in a cut. Feed rates and speeds provide the actual process change variables, but time in cut sometimes provides a much more visual impact of the most appropriate feeds and speeds. Unfortunately, time in cut may be the smallest part of the time consumed in countersinking.
Equation 11-1 provides an overview for all the time involved in drilling and countersinking with a drill followed by a countersinking tool.
where,
n = number of holes per part (requiring both drilling and countersinking)
m = number of parts to make
t total = total time in a drilling and countersinking operation
t load = time for workpiece loading and unloading
t s = set up time
t change = tool change time per part
t move = movement time from hole to hole
t c = countersink time
t rw = time to rework bad holes
t approach = spindle time to move tools down to workpiece
t incut = time of drill in cut
t retract = time the drill is retracting out of the hole
t cretract = time the countersink is retracting out of the hole
t deburr = the time required to deburr holes before they can be used.
The above equation does not define whether the countersink tool is changed...
