Implementation of Customer Requirements in Drawings



We are “build to print” subcontractor for producing of metal machined parts.

We have been working with one of our customers for many years. When concentricity and precision of two drilled holes is required, usually they are drilled in each part to small diameter (according to customer drawing), and then assembled and the holes enlarged later according to assembly drawing requirements. Usually, the following sentences in assembly drawings appeared to enlarged diameter: “drill in line” or “two concentric holes” or “drill and rean in line through two pilot holes”.

In our case there weren’t such notes in assembly drawings. In each separate part was requirement to drill small hole (diameter 40 mm), and assembly drawing showed final precision diameter of 46+0.02 mm in both parts, assembled “face to face”. In fact we drilled final precision diameter 46+0.02 mm of hole in each part separately.

As a result, we received customer complaint, that final precision holes in two parts were machined separately. Is there a place for customer complaint in this special case?


this is a tricky one.
Was there a technical review with the customer for this part where they'd specified what they wanted? Has the customer given you any written instructions (Engineering change etc) to illustrate their requirements?
If the answers are 'NO' then they only have themselves to blame for poorly communicating their requirements and you don't have to accept the complaint.
Going forward, I'd suggest having a technical review / Engineering review for every new project / drawing based on this lessons learned.
hope this helps
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