GlossaryKind of term: Manufacturing termRework
What is rework?
Rework is an extra, unplanned operation that brings a nonconforming part back within its requirements, such as re-milling a pocket floor left too shallow.
The extra operation sits outside the route, and the requirements themselves do not change. It differs from repair: after rework the part meets the drawing; after repair it is only fit for its intended use and the deviation remains, so the customer, or whoever owns the design, usually has to agree. An example: a pocket milled 0.1 mm too shallow goes back into the machine, is aligned again and the floor is re-milled.
What does rework depend on?
Whether rework is possible depends on the deviation. In machining it only works while there is still material that may come off: an undersized bore can be reamed, an oversized one cannot. Building material up by welding or plating and then remachining usually counts as repair, because the part then departs from its material or process specification. Other rework removes no material, such as deburring, cleaning or marking again. Still other rework first removes a layer, such as stripping and re-anodising, which can change the dimension. Reclamping can introduce a position error against features made earlier, so the datum has to be picked up again. A reworked part is inspected again against the requirements concerned; in some sectors rework also needs a method approved in advance.
How does rework work in practice?
Rework appears on no estimate line and still ends up in the hours. Book that time on the original operation and the standard looks too tight in the actuals, while the cause was a measuring error, a worn cutter or a program error. Booking it separately, with its cause, keeps the comparison clean. Whether rework is cheaper than a new part depends on the extra setup, the inspection, the risk of a second deviation and the value already in the part; after a surface treatment the part carries more value, but the layer often has to come off first and be applied again.
What is rework often confused with?
Rework is not scrap: the part stays in use and conforms afterwards; with scrap a new part starts. Nor is it a finishing pass: finishing, such as finish milling after stress relieving, is planned in the route; rework is not.
Frequently asked questions
Should I book rework separately?
If you want to use the actuals to adjust standards, yes. Otherwise the extra time lands on the original operation, while the cause lay elsewhere. Record operation and cause on a line of their own.
When is rework cheaper than a new part?
When a reliable correction is possible and the extra setup, inspection and risk together cost less than material and the whole route again. After a surface treatment the part carries more value, but the layer often has to be stripped and reapplied.
What is the difference between rework and repair?
After rework the part meets the requirements. After repair it is fit for its intended use but still deviates from the drawing. Repair therefore usually needs the customer's agreement, through a concession.