Guides / Sourcing / Choosing a Supplier

Running a First Article on a Part Where Appearance Is the Spec

July 10, 2026

A conventional first article inspection is a dimensional exercise: measure every feature on the drawing, record the result, sign it off. On an audio part that process can pass a component that is completely unusable.

The part has to be inspected twice, against two different kinds of specification.

Ask for the right thing

Put this in the PO rather than assuming:

Three pieces, or one complete matched set
Through the full production process, including the real finish, the real rack points and the real packing
Made on the production fixtures, not hand set up on a one-off
A dimensional report against the ballooned drawing
Photographs of the rack points and the packing, which cost the shop nothing and tell you a lot
A written note of anything the shop changed to make the part, because they usually change something and they usually do not mention it

That last point is the most valuable line in the whole exercise.

Inspect appearance first

Do this before you touch a caliper, while your eye is fresh and while you have no investment in the part passing.

Unpack it the way the customer will. If the packing damaged it, you have learned something about the packing before you learn anything about the part.
Arm’s length, diffuse light. Does it look right? Write down the first impression, because you will not have it again.
Rotate it slowly under the light. Directional finishes and anodize defects appear and disappear with angle.
Find the rack marks. Are they where you specified? Are they in a zone you declared non-cosmetic?
Check the grain direction on every brushed face, and check it is consistent across all three pieces.
Compare with the reference sample, physically side by side, touching, in the same light. Never from a photograph and never from memory.
Compare the three pieces with each other. This is the consistency test and it is the reason you asked for three.
Check the edges and the chamfers. Uniform? Over-blasted? Any witness lines where two toolpaths met?
Look at the marking. Position, depth, contrast, squareness.

Then measure

Standard dimensional work, with emphasis on the features that drive assembly rather than every dimension equally:

Features that set a visible gap
Cutouts that a control or a connector passes through
Mating faces and their flatness
Thread sizes and depths
Overall dimensions that affect fit in the chassis
Thickness where a finish operation may have removed material

Then assemble it

This is the step most often skipped and it catches the most expensive problems.

Fit the first article into the real assembly with the real mating parts. Look at:

Every visible gap, all the way round, for taper as well as size
Whether the panel sits flush, proud or recessed as designed
Whether controls are centred in their cutouts
Whether the screws seat without a washer standing proud
Whether anything fouls during assembly
How it looks from the angles a customer will actually see, which for a rack component means straight on and for a shelf component means slightly above

Record the decision

The output of a first article is not a yes or no. It is a written standard for everything that follows.

FIRST ARTICLE REPORT 1042-A
DATE: 2026-07-10
PIECES: 3, SERIALS FA-01 TO FA-03

DIMENSIONAL: PASS. SEE ATTACHED BALLOONED DRAWING.
  NOTE: FEATURE 14 MEASURED 12.06 AGAINST 12.00 +/-0.05.
  ACCEPTED AS IS, DOES NOT AFFECT FIT. DRAWING TO BE
  UPDATED TO +/-0.10 AT NEXT REVISION.

APPEARANCE: PASS WITH NOTE.
  COLOUR SLIGHTLY WARMER THAN REFERENCE 1042-REF.
  ACCEPTED. FA-02 BECOMES THE NEW REFERENCE SAMPLE.
  ONE COPY TO SUPPLIER, ONE RETAINED HERE.
  GRAIN DIRECTION CORRECT ON ALL 3.
  RACK MARKS ON REAR FACE AS SPECIFIED.

ASSEMBLY: PASS.
  GAP 1.1 TO 1.3 mm, WITHIN THE 0.9 TO 1.5 REQUIREMENT.

PROCESS LOCKED FROM THIS POINT:
  ALLOY 6061-T6, SAME MILL LOT WHERE POSSIBLE
  FINISHER: AS USED FOR FA
  RACK FIXTURE: AS USED FOR FA, TO BE RETAINED AND LABELLED
  NO SUBSTITUTION WITHOUT WRITTEN APPROVAL

APPROVED BY: [name]  DATE: 2026-07-10

Send it to the shop. Keep a copy. That document is what you will argue from in eighteen months when a batch arrives looking different, and it is what a new person at either company will read when they inherit the part.

When to reject

Reject a first article when the problem is in the process rather than in the piece:

Rack marks in a cosmetic zone, because every part will have them
Grain running the wrong way, because it is a fixture problem
Colour outside what you can live with, because the batch will be the same
Inconsistency between the three pieces, because that is the process talking

Accept with a note when the problem is a one-off: a single handling mark, a burr, a dimension you can open up. Fix the drawing at the same time so the next revision matches what you actually accepted.

Frequently asked questions

How many first article pieces should I ask for?

For a cosmetic part, three is better than one. One piece tells you the process can produce an acceptable part. Three tells you whether it produces them consistently, which is the actual question. For a matched set, ask for a complete set.

Should the first article go through the real finish?

Always. A raw machined first article tells you the geometry is right and nothing about the thing most likely to go wrong. If lead time is the reason for skipping the finish, split it: approve geometry on a raw part, then approve appearance on a finished one before the batch runs.

Who pays for the first article?

You do, and it is the best money in the project. Typical cost is a setup plus a few pieces plus one finishing cycle. Compare that with scrapping 120 anodized panels.

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Keep reading

This guide is part of Sourcing and Quality Control for Audio Parts, one of four sections in the guide library.