Quote validity: Quote validity is the period during which a supplier promises to honour a quoted price and lead time, after which the quote expires and must be re-priced.
A quote is a promise, and promises need an end date. Material prices move, machine schedules fill up and your own rates change. The validity period, often 14 to 30 days for custom parts, limits how long the buyer can accept the price as written.
Example: a shop quotes 100 nylon parts at €6.40 each on 1 March, valid for 30 days. The buyer places the order on 20 March and gets that price. If they come back on 15 April, the quote has expired and the shop re-prices it against current powder costs and capacity.
Validity is often confused with lead time. The validity period is how long the price stands; the lead time is how long production takes once the order is placed. A quote can be valid for 30 days and still promise delivery in 5 days from order.
Two practical points. First, a short validity period is not much use if the lead time promise is not tied to it as well: when your queue fills, the lead time you quoted three weeks ago may no longer be possible. Second, expired quotes are a useful signal. Tracking which quotes lapse without an order feeds into your win rate and shows where prices or lead times lose work.
For what else belongs in a quote, read how to quote manufacturing parts.
Go deeper: How to quote a manufactured part: the estimator's method