GlossaryKind of term: Manufacturing termDrawing change
What is a drawing change?
A drawing change is a released change to the drawing or model of a part, recorded as a new revision of that drawing or model.
The release comes from whoever owns the drawing, usually the customer as design owner; a change that has only been discussed or sits on a draft does not count yet. For a subcontractor it usually arrives as a known part at a higher revision: the flange you made at revision H comes back as revision J. On paper the change is often small, such as a bore going from ⌀12 to ⌀12 H7, a flatness from 0.1 to 0.05 mm or an added thread. Sometimes the model changed and the drawing did not, or the other way round.
How does a drawing change work in practice?
What changed decides what moves in the estimate. A tighter tolerance can call for reaming, an extra setup, a different machine or more inspection; a wider one can drop a step. If the geometry or the machining sequence changes, part of the program has to be reworked and programming time is incurred again; a change to a note or the title block alone usually leaves the program as it is. A change can also arrive while the previous revision is in production or in stock; then you agree what happens to those parts and whether price and lead time change with it. Adjusting only the previous price easily misses the line the change affects.
What is a drawing change often confused with?
A drawing change is not a repeat order: on a repeat order the revision is the same and the program can in principle be used as it is. The revision itself is the recorded state; the change is the difference between two revisions. Nor is it a new part: route and part of the preparation exist already, but you check them again. And a concession (deviation permit) leaves the drawing untouched: with it the customer accepts a deviation for certain parts or a batch.
How do you see a drawing change in Blake?
A new revision sits in Blake under the same part, next to the earlier ones. The values from the new drawing come in as proposals; whatever you confirm or correct can be traced to who did it and when. The estimate that follows is labelled as one. More on requests.
Frequently asked questions
Does a part cost more after a drawing change?
Not necessarily. A wider requirement can drop an inspection or an operation, a tighter one can add one. Read the revision table, compare drawing and model and recalculate the lines the change affects.
Which lines do I recalculate on a drawing change?
The lines the change affects. A tighter tolerance can affect setup, machining and inspection; a different material the material line and the cutting data; a new finish a subcontract operation. Programming time is incurred again when geometry or sequence changes.
What happens to parts at the old revision?
That is agreed with the customer: finish and deliver them, rework them to the new revision where possible, or scrap them. Who bears the cost of stock and work in progress belongs in that agreement.