Adding a Second Shift to Break a Bottleneck in EDGEBIC

Breaking a bottleneck with a second shift in EDGEBIC by User Solutions is a two-move play: identify the work center running near 100 percent utilization, then add a night shift to it in the Work Centers editor and reschedule. This walkthrough finds a jammed heat-treat station, doubles its capacity with one shift, and watches a week of late jobs recover, with the capacity math shown before and after. It is one of the worked examples we publish so the gain is visible in numbers.

For the discipline of finding the constraint first, the generic production bottleneck identification is the companion, and shifts and calendars explained covers the calendar model.

The Cast: One Jammed Heat-Treat Station

Copperline Metalworks has a plant that flows smoothly until it hits heat treat:

Every other work center in the plant has spare capacity. HEAT-1 does not, and that is the definition of a bottleneck: the one resource whose capacity caps the whole plant's throughput.

Step 1: Confirm the Bottleneck

Before adding capacity, confirm where the constraint actually is. Utilization in EDGEBIC is planned hours over available hours per work center. HEAT-1 carries 40 hours of demand against 40 hours of weekly capacity (8 h/day times five days), so its utilization sits at about 100 percent. The surrounding work centers sit well below that. HEAT-1 is the constraint, and it can also be marked with the bottleneck flag so the engine and the reports treat it as one.

The lesson worth stating plainly: adding a shift anywhere but the constraint moves nothing. A night shift on an already-idle machine just buys idle night hours. The whole return comes from putting the shift on HEAT-1.

Step 2: See the Backlog on One Shift

Run Drive Schedule as it stands. With one 8-hour shift and one instance, HEAT-1 can process exactly one 8-hour job per day:

Now suppose demand grows: two of the jobs move their due dates earlier, or a rush job jumps the queue. The station is already at 100 percent, so there is nowhere to put the extra work except later, and jobs start finishing after their due dates. The backlog has no reserve to absorb it, which is exactly what a bottleneck at full utilization looks like: no slack anywhere.

Step 3: Add the Night Shift

Open the Work Centers editor and select HEAT-1. Open its Shifts tab. Add a Night Shift, 16:00 to 00:00, and tick Monday through Friday. Save.

That is the entire change. There is no code, no manual slot entry. The capacity formula does the rest: capacity per shift is duration minus downtime minus partial holidays, times instances, times utilization. HEAT-1 now offers two shifts:

• Day Shift: 8 h x 1 instance x 100 percent = 8 h
• Night Shift: 8 h x 1 instance x 100 percent = 8 h

Daily capacity goes from 8 hours to 16. Weekly capacity goes from 40 hours to 80. The 16:00 to 00:00 shift crosses midnight, and the engine handles that correctly, computing its span as a full eight hours ending the next calendar day.

Step 4: Reschedule and Watch the Backlog Drain

Run Drive Schedule again. At the start of the run the engine rebuilds every capacity slot for every work center, date, and shift, so the new night shift's hours appear automatically. Jobs that were queued behind the day shift flow straight into the night shift:

All five jobs finish by Wednesday afternoon instead of stretching to Friday. The last job's lead time dropped by two full days. The late jobs recover, because the reserve that the second shift created absorbs the extra demand.

The station's numbers tell the same story. HEAT-1 now carries 40 hours of demand against 80 hours of weekly capacity, so its utilization drops from about 100 percent to about 50 percent. That is a healthy reserve, the space that lets the plant absorb rush jobs, rework, and variability without immediately slipping dates.

Any work already logged as actuals on HEAT-1 before the reschedule is preserved untouched; the reschedule only replans the work that has not started, which is the same actuals-are-immutable contract behind every EDGEBIC reschedule.

A Word on Where the Constraint Goes Next

Double a bottleneck's capacity and the constraint often moves somewhere else, because the plant can now push more work through HEAT-1 than the next station can take. This is normal, and it is why breaking a bottleneck is iterative: relieve one, find the next, relieve that. A month-end look across all your work centers is the way to spot the new constraint, covered in the month-end capacity review.

What This Walkthrough Proves

1. The constraint is where the capacity goes. A shift added anywhere but the bottleneck buys idle hours; the whole return comes from adding it to HEAT-1.
2. Capacity is arithmetic. A second 8-hour shift doubles the station from 40 to 80 weekly hours, and utilization halves.
3. Adding a shift is a calendar edit. Open the Shifts tab, tick the days, save; the next run rebuilds the slots automatically.
4. Overnight shifts count fully. The 16:00 to 00:00 shift contributes its full eight hours ending the next day.
5. The backlog drains on the reschedule. Queued jobs flow into the new shift and late jobs recover, while logged actuals stay put.

If a work center shows zero capacity after a shift edit, or a holiday did not reduce capacity as expected, those are known symptoms with documented fixes: capacity shows zero for a work center and a holiday did not reduce capacity.

From One Shift to a Balanced Plant

Adding a shift is the bluntest capacity lever, and the most effective when it lands on the constraint. For a subtler capacity move, onboarding a new work center and rebalancing adds a whole machine, and when you only need extra hours for a single day rather than every week, running a weekend on a capacity override is the lighter touch.

User Solutions has helped manufacturers relieve constraints since 1991, work that took GE Railcar from 30 percent to 90 percent on-time. Contact us for a demo and bring your busiest work center: we will find the constraint with you.