What is a ballooned drawing, and how does it tie each callout to the inspection report?

Why do inspection reports depend on a ballooned drawing?

The balloon number is the only key that joins a measured value to the requirement it was checked against. Without it, a reviewer cannot prove that the report covers the whole drawing, or tell which of two similar diameters a value belongs to.

A typical machined housing carries dozens of requirements: sizes, feature control frames, thread callouts, surface texture symbols, a general tolerance block, and notes about edges, finish and marking. An unballooned report usually lists the dimensions the inspector found easy to measure and silently drops the rest. The notes and the title-block tolerance are the most common casualties, and they are often the ones that cause trouble at assembly.

Aerospace formalized the idea in SAE AS9102, whose Form 3 (characteristic accountability) expects every design characteristic to carry a unique reference that ties it to a recorded result; ballooning is the usual way to create that reference. The automotive production part approval process asks for dimensional results for every characteristic on the design record, and the AIAG PPAP manual is why automotive suppliers are used to submitting a marked-up print with the dimensional results. Outside those two industries nothing obliges a supplier to balloon, which is exactly why an industrial buyer has to ask for it in writing.

The ballooned print also settles disputes. When a lot is rejected, both sides can point to balloon 14 instead of arguing about “the second bore from the left on the section view.” Corrective-action reports, deviation requests and gauge plans can all use the same number for as long as the part is made.

What should get a balloon on the drawing?

Every requirement that a part can pass or fail gets a balloon, not just the dimensions with numbers next to them. That includes notes, the general tolerance block, threads, surface texture, material, finish and marking requirements.

• Toleranced sizes and locations. One balloon per dimension, including chamfers, radii and depths that carry a tolerance from the general note.
• Feature control frames. Balloon the frame, not the basic dimensions that locate the tolerance zone. Per ASME Y14.5, a basic dimension is a theoretically exact value with no tolerance of its own, so measuring it in isolation proves nothing; the position or profile result in the frame is the requirement. Some customers' PPAP or first-article instructions ask for basic dimensions to be ballooned as well; if yours do, have those lines marked as basic and point them to the frame result.
• Thread callouts. One balloon for the thread designation and class, with the gauge method stated. If the callout also specifies a full-thread depth, that depth is a separate characteristic.
• Surface texture symbols, finish and coating notes. A finish callout can be verified by a certificate of conformance rather than a measurement, but it still needs a line so the report shows it was checked.
• Material callout. Usually verified against a material certificate; the report line should reference the certificate or heat number.
• Every numbered note and flag note. “Remove all burrs,” “break sharp edges,” “no tool marks on surface X” and marking requirements are all inspectable, and all are routinely skipped when they have no balloon.
• The general tolerance block. A single balloon that covers “all untoleranced features” forces the supplier to state how those features were verified.

Reference dimensions, shown in parentheses or marked REF, are not requirements and should normally not be ballooned; if they are, the report should mark them as reference only. Repeated features called out as 4X or 6X get one balloon with sub-numbers, as in rows 3 and 4 of the table, so each hole has its own result. Recording only the worst of four holes hides how the pattern is drifting.

Should the buyer or the supplier balloon the drawing?

If you buy the same part from more than one source, or plan to, balloon it yourself and send the ballooned copy with the RFQ. If the supplier balloons it, require the ballooned copy back with the first article and approve its numbering before production reports start.

A buyer-ballooned master makes reports from different suppliers directly comparable, and it puts the decision about what counts as a characteristic with the people who own the design. It also exposes drawing problems early: an engineer who balloons a drawing line by line tends to find the missing tolerance, the conflicting note or the datum that cannot be set up.

When the supplier does the ballooning, the risk is quiet omission. Automatic ballooning software that reads a PDF or a 3D model saves time, but it can miss notes, merge stacked callouts or skip text in the title block. Review the returned copy against the drawing before you accept the first article report. Where a part is defined by a 3D model with annotations under ASME Y14.41 instead of a 2D drawing, the same rule applies: every annotated requirement needs a unique identifier that appears on the report.

How do you require a ballooned drawing in the RFQ and purchase order?

Put the requirement in writing on the RFQ so it is priced, and repeat it as a quality clause on the purchase order so it is enforceable. Specify what gets ballooned, what each report line must contain and when the package is due.

Wording along these lines works for most machined, cast and stamped parts:

“Supplier shall provide a ballooned copy of drawing [number], revision [letter], with a unique number on every characteristic, including all notes, the general tolerance block, threads, surface texture, material and finish requirements. The first article inspection report shall contain one line per balloon showing the requirement, the measuring method and gauge identification, the actual measured value for variable characteristics and pass or fail for attribute characteristics. Results shall be reported in the units of the drawing. Any nonconforming characteristic shall be identified and reported before parts ship. A new ballooned drawing and first article report are required after any drawing revision, change of material source, change of process or tooling, or change of manufacturing location.”

Two additions are worth considering. First, mark the critical or key characteristics on your ballooned copy and ask for those balloons to be measured on every production lot, not only at first article; the sampling plan for them is covered in the AQL sampling guide. Second, if your own customer works to SAE AS9102 or PPAP, say so, because the form layout and approval steps then follow that system rather than the supplier’s own format.