1. Stitch time
StitchCapacity asks for minutes per 1,000 stitches. That is easier to measure and audit than pretending rated maximum SPM is the speed of every design.
When the planner mixes caps and flats, it uses a weighted average of the separate flat and cap values entered.
2. Synchronized head utilization
A synchronized multi-head cannot use more heads than there are identical pieces ready for that cycle. We model the last partially filled cycle inside the average same-design batch.
Example: a 10-piece repeated batch on a 4-head machine needs three cycles with 12 available head-slots, so modeled head utilization is 10/12 = 83.3%.
3. Machine throughput
Independent single-head machines are modeled without the synchronized partial-batch penalty because each unit can run a different job.
4. Operator supply
Handling includes active hooping/loading time as entered. Pre-hooping can shift labor outside the sewing cycle, but it still consumes people-hours across the shift.
5. Effective throughput
The slower resource is the bottleneck.
6. Good-piece capacity
The production planner compares this with target pieces plus the capacity buffer you request.
7. What is intentionally not modeled
- Automatic scheduling across many live orders
- Blank inventory and purchasing readiness
- Artwork approvals, digitizing queue and sew-outs
- Machine telemetry, maintenance state or unexpected breakdowns
- Thread/stabilizer/needle selection, tension or stitch-file quality
- Guaranteed completion dates, fit, earnings or machine performance
Why defaults are placeholders
Current official machine examples publish maximum speeds from roughly 1,000 to 1,500 SPM, and one Brother multi-needle sell sheet publishes a lower cap-frame range than standard frames. That variation is precisely why the calculators expose assumptions rather than hiding a universal efficiency factor.
Mixed-order queue model
The queue planner preserves each job's product type, quantity, stitch count and same-design batch. For synchronized heads, each job is split into production cycles, so a small batch cannot magically use heads that have no matching garment. For independent single-head fleets, pieces are assigned across separate machine timelines so a single garment is never split across machines. This keeps tiny jobs from receiving impossible fractional-head speedups while still allowing unrelated work to occupy different machines.
The result is a planning bound, not a full discrete-event job-shop optimizer. It models machine timelines, batch effects, changeover allowance and operator workload, but artwork, stock staging, maintenance surprises and shipping remain outside the schedule unless you cover them with conservative changeover time and reserve capacity.
Machine scorecard
The scorecard gives the most weight to capacity and hard workload fit. A candidate that exceeds the stated maximum budget, misses required sewing field/cap support, or falls short of good-piece capacity is explicitly flagged before the weighted score. The entered reject/rework allowance reduces capacity; needle palette, warranty and service-distance proxy then contribute to a transparent secondary score.
Growth and downtime models
The growth planner compounds the user's monthly demand assumption and compares normal and peak-stress demand with capacity after the chosen reserve. The downtime calculator does not assume one architecture is more reliable; it uses the user's own downtime hours and shows both expected head-hours at risk and concentration from a single outage.