Purchased part

A purchased part is a component or part bought ready-made from a supplier rather than manufactured in-house, such as a standard fastener, bearing, or a specialized component outside a factory's own capability. It appears on a bill of materials alongside in-house manufactured parts.

Why purchased parts are estimated differently from in-house parts

A purchased part's cost and lead time depend on the supplier's pricing and delivery, not on the buying factory's own machine time or process planning, which is why it's tracked and estimated differently from an in-house manufactured part.

Where purchased parts appear

Typically identified on a bill of materials or assembly drawing rather than requiring its own manufacturing drawing, though a specification may still apply.

Common mistakes

Treating a purchased part's lead time as controllable the way in-house machining time is; supplier lead time and stock availability are outside a factory's direct control and can become a bottleneck.

Is a purchased part the same as an outsourced operation?

Related but distinct; a purchased part is bought as a finished component, while outsourcing typically means sending an operation on an otherwise in-house part to another supplier.

Does a purchased part need a manufacturing drawing?

Usually not its own; it's identified on a bill of materials, though a specification (standard, grade) may still apply.

Why can purchased parts become a scheduling bottleneck?

Because their lead time depends on the supplier, which a factory doesn't directly control the way it controls its own machine time.