Methodology / Monthly capacity

Monthly capacity — definition and counting

Conforming units deliverable within one month. It is not the theoretical output of the equipment.

Unit

units / month

Formula

machines x cycle time per unit x effective hours x yield x utilisation

Why suppliers disagree

• Shifts: one shift of eight hours, two shifts or three shifts triples the same equipment
• Blank or finished part: whether upstream casting and downstream heat treatment are included
• Outsourced steps: many plants count subcontractor capacity as their own
• Which yield: trial yield, volume yield, or the best month
• Utilisation assumption: 85% and 60% are different businesses
• Planned versus commissioned capacity: 'at full ramp' in a placement document is not today

How to collect it on site

• Count nameplates and machines on site; do not rely on what you are told
• Read actual cycle time from the process card, not theoretical time from the routing document
• Ask for the outsourcing share and the name of the subcontractor
• Ask for the last three months of shipping records and divide units by months
• Ask for planned, under construction and commissioned as three separate answers

The three most common misreadings

1. Treating design capacity as actual capacity, which is routinely 30% higher
2. Treating a peak month as an average month; peak-season data has no reference value
3. Ignoring changeover time, which can consume half the capacity in high-mix low-volume work
4. Taking 'planned capacity' in a listed-company announcement as current capacity