Why 100% booked is not 100% healthy
A schedule built to theoretical maximum assumes every blank is ready, every design is approved, every operator is available, every run matches its estimate and nothing needs to be reworked. Real shops rarely get all of those conditions at once. When every modeled hour is already sold, ordinary variation becomes a missed promise.
Reserve also protects decision quality. Without room, a small rush order can displace a larger profitable job, preventive maintenance gets postponed and operators may spend the day reacting instead of sequencing work deliberately.
Measure good capacity before choosing a reserve
Start from completed, sellable pieces under a representative mix—not heads multiplied by rated SPM. Use several ordinary weeks or timed runs to estimate stitch time and handling time, then include normal rework. The calibration tool turns timed samples into planning inputs, while the capacity planner converts those inputs into good output.
If your measured capacity already includes typical stops and handling, do not subtract the same loss twice. The reserve is for uncertainty and future commitments, not a second copy of every observed inefficiency.
How to choose a practical starting reserve
There is no universal percentage. A stable contract shop with repetitive batches may need less spare room than a shop that accepts one-off personalization, school rushes and cap work with volatile due dates. A useful way to choose a starting point is to list the disruptions that routinely consume unplanned time and estimate their combined weekly impact.
| Signal | What it suggests |
|---|---|
| Rush work arrives every week | Reserve must leave room for orders not known on Monday. |
| Frequent personalization | Small batches and setup variation increase schedule uncertainty. |
| One critical machine | Maintenance and outage concentration justify more breathing room. |
| Highly repetitive contract batches | Measured variability may be lower, so reserve can be evidence-based rather than arbitrary. |
| Seasonal spikes | Model peak demand separately instead of using one annual-average reserve. |
Review the chosen reserve after several weeks. If it is almost never touched, you may be too conservative. If it disappears by midweek, the reserve is describing a real capacity shortage rather than protecting one.
Model normal demand and peak demand separately
A shop can be comfortable in spring and structurally short before a school or holiday season. The Growth & Peak Capacity Planner keeps a normal demand curve and a peak multiplier separate so you can see when each crosses usable capacity.
Do not wait for the exact crossing month to start equipment research. Quote collection, financing, delivery, training and workflow changes have lead time. The useful trigger is when evidence says the crossing is approaching, not when the backlog is already painful.
Use backlog behavior as a second signal
Reserve percentage is an input. Backlog is an outcome. If new work is arriving faster than good pieces leave production, the queue grows even if individual machines appear busy. That makes backlog a useful independent check on your capacity assumptions.
Use the Backlog Clearance Planner to compare daily good capacity with new daily arrivals. If net clearance is close to zero, a small disruption can make the queue persistent. If net clearance is comfortably positive, you can estimate how many production days are required to return to normal.
A simple monthly review
- Record good pieces completed and actual production hours.
- Compare planned versus actual stitch and handling assumptions.
- Record how much reserve was consumed by rushes, rework and downtime.
- Check whether backlog returned to normal after the peak.
- Only then change the reserve target or start an equipment study.
Keep the reserve stable long enough to observe it. Changing the target after every unusual day makes it impossible to distinguish real capacity pressure from random variation.
Forecast the crossing
See normal and peak-ready runway.
Use measured good capacity and a deliberate reserve rather than brochure maximums.