Lot Control
A reel of 5000 and a strip of cut tape are not the same stock, even when they hold the same part. Without lot control, PartsBox knows only the total: you add to it, you remove from it, and all you can see is the quantity. You cannot tell one reel from another, what each cost, or which one a build used.
With lot control, every batch you receive is a distinct lot, with its own quantity, storage location, purchase price, and source. Buy a reel of 5000 10µF capacitors and store it in A1, then buy a second reel and put it in the same bin, and the total is 10,000 — but PartsBox keeps them as two lots of 5,000, each with its own order and its own cost. When you build, you pick the lot you draw from, and PartsBox tracks what is left on each.
Lots work the same way for parts that are measured rather than counted. One lot of wire might start as a spool of 100 meters and another as a spool of 50 meters, and PartsBox tracks the remaining length of each in the part's unit of measure as you consume it.
What is usable, and what is not
The total on hand and the amount you can actually build with are two different numbers, and lot control keeps them apart. Tag a lot as quarantined, mark it expired, or note that it has gone to a contract manufacturer, and PartsBox leaves it out when it picks stock for a build. Ship one reel of that 10µF capacitor to your CM and the total is still 10,000, but only 5,000 is usable on-site.
Tags drive this. Tag a lot as belonging to a customer or as house stock, and you can build a job only from the lots it is allowed to use — the way consigned inventory has to work. Record a use-by date, and with strict expiration turned on, PartsBox refuses to build from a lot that has expired.
Exact per-lot cost
Each lot keeps the price you paid for it. When a build consumes parts, the cost comes from the specific lots it used, and a lot split inherits the cost of its parent. Build cost and inventory value then reflect what you actually paid, lot by lot, instead of a blended average across every purchase. This is the only way to get an exact cost of goods for a production batch when component prices move between orders.
Without lot control, valuation falls back to weighted-average cost. That is a reasonable approximation, but it cannot follow the price differences between one purchase and the next.
Traceability follows from lot control
Because every build records the exact lots it consumed, lot control gives you two-way traceability: forward from a supplier lot to the devices that used it, and backward from a device to its sources. Turn on serial numbers and every unit you build becomes its own lot, with a unique code that carries its test and service records.
Lot control without the overhead
Most small and medium manufacturers skip lot control, because traditional systems make it expensive: software to buy, staff to train, and careful data entry for every lot received, stored, and consumed. PartsBox removes almost all of that overhead, so you get the benefit without a rollout project.
When you add stock, lot information is optional. Enter your own lot name, a description, an expiration date, and comments if you want them, or enter nothing and PartsBox still assigns a unique lot ID and shows a short 8-character code everywhere. Lot control can be strict or relaxed. Under strict control, stock with no lot cannot be used for a build, so older stock has to be removed and added again. Under relaxed control, any stock can build, with less traceability.
This is the lot information for a single part:
The screen gathers the lot's value summary — purchase quantity, unit cost, purchase value, current quantity, and current value — the part data, where the lot came from, which builds used it, and which sub-assembly parts contain it. For a part with a unit of measure, every quantity is shown in that unit.
Regulated industries
In medical, pharmaceutical, aerospace, and defense work, traceability is not optional: you have to show where parts came from, where they were used, and be able to recall a specific batch. Lot control is what produces that evidence, and it is the record of Good Manufacturing Practice an auditor looks for. Medical-device startups are often caught out here — even an early prototype has to be built with traceability, long before anyone schedules an audit. See Title 21 CFR Part 11 for what regulated electronic records require.
Lot data is also available through the API, so you can connect it to ERP, supply-chain, or quality-management systems.
Lot control and serial numbers are on the Control plan. The immutable audit trail, which records every change for audits and US FDA 21 CFR Part 11, is on the Compliance plan.