A first article inspection report is the first document that tells you whether the supplier understood your drawing. It is also the document most often read too quickly, because the format looks reassuring: every line says pass. The useful information is not the pass mark, it is the margin.
What should a first article inspection report for a deep drawn part contain?
A first article inspection report for a deep drawn part should list every toleranced characteristic as a numbered line with the nominal, the tolerance and the measured value, using gauges that are named and in calibration. On a drawn part that must include the wall thickness at the height the drawing specifies, because the wall is a gradient rather than a constant. It should also carry the outside diameter and the bore with their concentricity or runout relationship, the overall height and any stepped heights, the radii that decide the draw, and the finish on any sealing face. Material certification traceable to the mill and the drawing revision the report was inspected against belong on the report too. The honest signal is the margin: values sitting comfortably inside the tolerance show control, values crowding one limit show a process that will drift out of it.
The lines that get missed on drawn parts
- Wall thickness without a measurement height. If the drawing names a thickness but not where, the report may be measured anywhere and still pass.
- Concentricity or runout. Often reported as two separate diameters, which says nothing about whether the part assembles.
- The sealing face finish. A drawn surface is usually too rough to seal, so if a face has to seal, the report should show the finish and how it was obtained.
- Burr and cleanliness. Both matter when the part feeds a sensor element, and both are easy to omit.
- The revision. A report against a superseded drawing is worse than no report, because it looks complete.
How to read it
Check three things beyond the numbers themselves: that every tolerance on the drawing appears as a line, that the gauges are named and calibrated, and that the values are not clustered on one side of nominal. A report where every dimension sits exactly at nominal is usually a report that was typed rather than measured. Then ask for the first article itself, and have two or three functional features measured independently - that comparison is the part of the exercise that cannot be produced by formatting.
Key point
Read the first article inspection report for coverage, for named and calibrated gauges, and for margins - not for the word pass. On drawn parts the two lines most often missing are the wall thickness at its measurement height and the concentricity that decides assembly.
Frequently asked questions
What has to be on a first article inspection report for a deep drawn part?
Every toleranced characteristic as a numbered line with nominal, tolerance and measured value; the wall thickness at the height the drawing specifies; concentricity or runout between bore and outside diameter; heights; sealing-face finish; material certification traceable to the mill; and the drawing revision inspected.
Why is wall thickness different on a drawn part?
Because the wall is formed from the flange and thins as it is stretched over the die radius. The thinnest point is just above the punch nose and the thickest is near the open end, so a single thickness figure with no measurement height cannot be verified.
What is the strongest signal in a first article report?
The margin. Values sitting comfortably inside the tolerance indicate a process in control; values crowding one limit indicate a process that will drift out. A report where every value reads exactly nominal usually indicates the numbers were transcribed rather than measured.
Should I measure the first article myself?
Yes. Have two or three functional features measured independently on the part you hold and compare them with the report. It is the one check that cannot be satisfied by better formatting, and it is quick.