Directing a component is a legitimate engineering decision. It also moves a piece of the supply risk back onto your side of the table, and that should be explicit.
Most industrial programs are hybrid: the customer directs the critical components and the supplier sources the rest. That split is sensible — you know your application, we know our supply base — but it only works when the consequences of each side of the split are agreed in advance.
When a part is directed, the supplier can still inspect it, store it and account for it, but cannot change it, second-source it, or absorb its lead time. If a directed component is late, the build is late, and no amount of supplier expediting fixes that. Saying so at quotation is not passing the buck; it is describing the mechanics.
Directed parts also carry a documentation duty. The approved manufacturer, part number and any approved alternates need to be released, not implied. A directed component with an ambiguous specification is the single most common source of an incoming-inspection dispute.
Our practice is to name directed parts explicitly in the quotation, list their lead times, and flag any with an MOQ or an end-of-life risk. That way the split is visible before the first order rather than discovered during the first shortage.
— GANI Manufacturing engineering team