Capacity verification: checking there is room for your volume, not just for your part

Find the operation that runs out first

Capacity is set by a constraint, and the constraint is rarely the machine on the brochure. It can be a single finishing cell, one setter qualified on the tooling, a curing or drying stage with fixed duration, a test station shared across the plant, inspection headcount, or floor space for materials. Ask the site which operation constrains the process family your product uses, and whether it is equipment, labour or space. A management team that answers immediately and specifically is running the plant. One that talks about total machine hours has given you an arithmetic exercise rather than an operational answer.

Your volume arrives beside somebody else's

Nominal capacity means little; uncommitted capacity is the figure that matters, and it changes as their order book does. Ask what share of the constraining resource is already committed, how far ahead that commitment extends, and whether existing customers hold contractual priority. Seasonality deserves particular attention: if their established accounts peak in the same months you do, you will compete for the same machine at precisely the worst moment, and a plant that looks comfortable on an annual view will be gridlocked twice a year. Overlapping peaks are not a reason to walk away, but they must be discussed before award rather than discovered during one.

Order rhythm strains a plant more than annual volume does

The same yearly quantity behaves completely differently when it arrives as steady weekly call-offs, as occasional large campaigns, or as unpredictable bursts against customer orders. Changeover time, minimum economical run length, cleaning requirements between products and material batching all determine which pattern the site can serve without punishing you on price or lead time. Describe your real order profile, including the ugly parts, and ask how the plant would schedule it. If the answer assumes stable, evenly spaced releases and your business does not work that way, you have found a mismatch that will surface as expediting and missed dates.

Test the claim against evidence they already hold

Capacity statements are forecasts; production records are history. Ask for recent output of a comparable product on the equipment you would use, expressed as what was actually shipped rather than what was planned. Look at unplanned downtime, at how maintenance windows are protected, at scrap and rework, since every rejected unit consumes constraint time twice. Ask about staffing: whether a further shift is genuinely available depends on local labour supply, on how long a new operator takes to become useful, and on whether the shift premium was in the quotation. Verified history beats a spreadsheet every time.

What actually happens when you need more than the plan

Growth and demand spikes are where capacity promises are tested. Establish what a step up would require in practice: additional tooling with its own manufacturing lead time, another machine that has to be bought and commissioned, people who must be recruited and trained, or floor space that does not exist. Ask how long each takes and who pays. The commercial terms should record the upside you can call on and the notice needed to trigger it, so that a surge conversation is a schedule discussion rather than a negotiation held during a shortage, when your leverage is at its lowest.

Frequently asked questions

How do we verify capacity when they will not show us other customers' volumes?

You do not need their customer data, only the shape of the load. Ask for committed utilisation of the constraining resource as a proportion, for the horizon over which it is booked, and for the months where it is tightest. Walk the floor and count what is running and what is idle. Ask when the equipment you would use was last stopped for want of work. Aggregate answers protect their confidentiality and still tell you whether there is genuine room for you.

Is it worth paying to reserve capacity?

Sometimes, and it should be an explicit trade rather than an assumption. A reservation only means something if it names the resource, the period and what happens when either side fails to use or provide it. Buyers frequently believe they hold priority because a salesperson said so, then find their work rescheduled behind a larger account. If capacity genuinely constrains your business, put the commitment in the commercial terms and expect to give something in return, usually volume certainty.

What does it mean when a shop says it can always add a shift?

It means the equipment is free at night, which is the easiest part of the problem. The harder questions are whether trained operators and setters exist locally, whether supervision and quality cover extend to that shift, what the pay premium does to your price, whether maintenance still gets its window, and whether the constraint is even the machine. Ask what they ran the last time a further shift was needed, how long it took to staff, and how output per hour compared with the day shift.