Track every reel, cut-tape strip, and batch as its own lot, and three things become exact: how much stock you have, what it cost, and which units used it. Without lot control, PartsBox gives you a part's total. With it, each batch is a distinct lot, with its own quantity, storage location, purchase price, and source, and you choose which lot a build consumes.
The first payoff is accuracy, not audit. Build cost and inventory value come from the lots actually consumed, at the price you paid for each, not a blended average — the only way to get an exact cost of goods when component prices move between orders. On-hand stock and stock usable for production stay separate numbers: set a lot aside — quarantined, expired, or shipped to a contract manufacturer — and PartsBox leaves it out when it picks stock for a build. Tag lots as house stock or as a client's consigned stock, and a job builds only from the lots it is allowed to use. Record a use-by date, and with strict expiration on, PartsBox refuses to build from an expired lot.
None of this needs a data-entry regime. Lot information is optional when stock arrives: enter a name, a description, an expiration date, and comments if you want them, or nothing at all — PartsBox still assigns each receipt a unique lot with a short code shown everywhere, and receiving against an order links the lot to where it came from.
A lot carries files. Attach the incoming-inspection record, a certificate of conformance, or a supplier's test report to the lot it belongs to, and it is there when an auditor — or a colleague — asks. Splitting stock does not lose anything: cut a length from a reel or set part of a batch aside, and each new lot keeps its parent's cost and its link back to the original.
Turn on per-unit tracking and every device produced becomes its own lot of quantity one, identified by a unique ID Anything™ code — that code is the serial number. There is no central counter to coordinate across sites, and no duplicates after a database restore; when a customer requires their own serial format, attach it to the unit as its name or a custom field. Attach a test report, an inspection photo, or a repair record to a unit, and it stays with that one device for its whole life. Regulated manufacturers often start a build with a documentation-only first stage, so every unit exists — labeled and scannable — before the first component is placed.
A distributor flags a bad date code. Find the supplier lot, and traceability lists every build and every serialized unit that drew from it; from a returned unit, the trace runs backward to the exact lots inside it and the orders they arrived on. That is the evidence an audit or a recall needs, produced from records that accumulated on their own as you worked.
Lot control and serial numbers are on the Control plan. The immutable audit trail, which records every change for US FDA 21 CFR Part 11, is on the Compliance plan.