How to Balloon an MBD Model for First Article Inspection

To balloon an MBD model for FAI, you assign a unique characteristic number to each applicable design characteristic in the product definition, including applicable PMI, notes, and requirements defined by the model geometry. Then you capture those numbers in a format the customer can review, such as a ballooned 3D PDF, annotated saved views, or another format accepted by the customer's FAI requirements. Each balloon becomes one row on AS9102 Form 3, just as it would on a 2D drawing.

More primes now release parts as MBD datasets, where the 3D model and its annotations define the part and no 2D drawing is supplied. The FAI requirement does not change: AS9102 still expects every design characteristic to be numbered and accounted for. What changes is where those characteristics live and how you show a reviewer which balloon belongs to which feature.

This guide walks through three ways to balloon a model-based definition, what to confirm with your customer before you start, and how to account for the requirements that never appear as an annotation at all.

Why ballooning an MBD model is different

On a 2D drawing, every requirement sits on a sheet you can print, mark up and circle. In an MBD dataset there is no sheet. Dimensions, GD&T feature control frames, datum targets and notes are attached to faces and edges of the 3D model, and they are usually organized into saved views that the designer set up to show related callouts together.

A few things change for the quality team:

• Where the requirements live. Some are annotations you can see. Others are "basic" values you only get by querying the CAD geometry, because the model itself is the dimension. A general note such as "all non-toleranced surfaces within 0.5 mm profile to datums A|B|C" can cover hundreds of features with a single line of text.
• Whether software can read them. NIST separates PMI into two kinds. Graphical PMI (also called presentation PMI) is meant to be human-readable: lines and symbols that look right on screen. Semantic PMI (PMI representation) carries the actual tolerance values and the geometry they reference, which lets CAD, CAM and CMM software "process the PMI directly" (NIST). Automated 3D ballooning depends on semantic PMI. If you receive graphical-only PMI, plan on numbering it by hand.
• What you hand back. A ballooned 2D drawing is a familiar deliverable. For a model, you and your customer need to agree on what the reviewer will look at to trace balloon 14 back to the feature it describes.

Before you balloon: five questions for your customer

These answers decide which method below you can use and what your FAIR package has to contain. Settle these before anyone numbers a single callout.

1. Which file is the authority? A native CAD model, a STEP AP242 file and a 3D PDF can all come from the same design, but translation can drop or alter PMI. Confirm which one governs and record its exact identifier and revision on Form 1. A reference drawing alone is not that authority.
2. Is the PMI semantic or graphical? Open the file in a viewer that can tell the difference. If the feature control frames are just lines and text, your software will not pick them up automatically.
3. What evidence of ballooning do they expect? Some primes want a ballooned 3D PDF. Others accept screenshots of each saved view with balloons visible. A few still ask for a derived 2D sheet. Get this in writing, ideally from the supplier quality manual or the PO notes.
4. How should model-defined dimensions be handled? Ask whether you need to balloon every basic dimension you extract from the geometry, or whether the general profile note plus a CMM report against the model satisfies it.
5. Are key characteristics flagged in the model? On a drawing they carry a symbol. In a model they might be a PMI attribute, a note, or a separate list. Find out where.

Method 1: Balloon the PMI directly in MBD-aware software

This is the cleanest option when the model carries semantic PMI. The software reads each annotation as data, so the balloon is tied to the callout itself rather than to a spot on a picture.

1. Import the authority file. Load the native model or STEP AP242 file your customer named. STEP AP242 is the neutral format built to carry 3D PMI along with geometry; SOLIDWORKS MBD, for example, has exported it with PMI since the 2017 release (CATI).
2. Check the PMI came through. Compare the count of dimensions, feature control frames and datums against the native file or the customer's 3D PDF. A missing datum target is easy to overlook in a tree of 200 items.
3. Run auto-ballooning. Tools such as Verisurf assign IDs "in consecutive order" following the dimension and tolerance order in the model tree, and the balloons can sit on geometric tolerances like profile and position as well as plain sizes like diameters and angles (Verisurf).
4. Renumber for readability. Tree order is rarely inspection order. Group by saved view or by datum setup so the inspector isn't flipping the part between balloon 3 and balloon 4.
5. Add what the software missed. Notes, material callouts, finish specs and any graphical-only PMI need manual balloons. So do the model-defined dimensions covered later in this guide.
6. Export the bill of characteristics. This list feeds Form 3 and, in many tools, the CMM program. After auto-ballooning, export the characteristic list to Excel or inspection software so measurements map back to the same balloon numbers.

The catch: these tools assume clean semantic PMI. Give them a translated file with broken associations and you'll get balloons pointing at nothing.

Method 2: Balloon a 3D PDF

Many primes release MBD as a 3D PDF so suppliers without the original CAD package can still rotate the part and read the annotations. That makes the 3D PDF a common, practical surface to balloon on.

1. Open each saved view in turn. The designer built these views to group related callouts. Ballooning view by view keeps the numbering easy to follow and matches how a reviewer will walk through the file.
2. Place balloons next to each annotation. Use the markup or comment tools in a viewer that supports 3D content. Keep the balloon close to the callout and off the geometry so it stays legible when the view is spun.
3. Number continuously across views. View 1 might hold balloons 1 to 18 and view 2 picks up at 19. Don't restart at 1 for a new view; Form 3 needs a single sequence.
4. Capture a static image of every ballooned view. Annotations in a 3D PDF can shift or hide depending on the viewer. A flat snapshot of each view, saved with the FAIR, gives the reviewer something that won't move.
5. Log notes and model-queried values separately. A 3D PDF shows what the designer annotated. It won't show you the basic dimensions you had to measure off the geometry, so list those with their own balloon numbers and a reference to where they came from.

The tradeoff is that 3D PDF balloons are graphics. Nothing links balloon 27 to the profile tolerance underneath it, so a new model revision means checking every balloon by eye.

Method 3: Build a 2D reference sheet from saved views

Some shops, and some customers, still want a flat sheet they can print and check off. You can build one from the model, as long as everyone understands it is a reference and not the definition. A customer-provided reference drawing does not define requirements on its own—if PMI is missing on that sheet, you still balloon from the governing 3D model and PMI, not from an empty flat file.

1. Export each saved view as an image or drawing view. Most CAD packages can place model views, with their PMI, on a 2D sheet.
2. Label the sheet clearly. Add a note such as "Reference only. The 3D model [file name, revision] governs." Without it, the sheet can drift into being treated as a released drawing.
3. Balloon the sheet with your normal 2D tool. This is where existing ballooning habits and software pay off.
4. Cross-check the count. The number of PMI items in the model, plus notes, plus extracted dimensions, should equal your balloon count. If the sheet shows fewer, something got hidden by the view orientation.

It is the quickest method to adopt with existing tools, but it adds maintenance. Every model change means regenerating the sheet and re-ballooning it, and if the reference sheet and the model disagree, the model wins.

Which method should you use?

Pick based on what you received and what your customer will accept. Many suppliers use more than one: auto-balloon the semantic PMI, then document the views in a 3D PDF for the reviewer.

How to balloon requirements that aren't annotated

A model can be fully defined while showing only a fraction of its requirements as visible callouts. AS9102 still expects every design characteristic to be accounted for, so the unannotated ones need balloons too.

General notes. Give each note, or each separate requirement within a long note, its own balloon. A note listing a material spec, a finish and a marking requirement is three characteristics. The material and process specs also belong on Form 2.

General profile tolerances. A note like "all surfaces 0.25 profile to A|B|C unless otherwise specified" is one balloon. Your evidence is usually a CMM color map or point-cloud comparison against the nominal model, referenced on that Form 3 row. Confirm with your customer whether they also want key surfaces broken out individually.

Basic dimensions queried from the model. When a position tolerance references a hole whose location is only defined by the geometry, you measure that location in CAD to get the nominal. Record the queried value and how you got it. Some customers want each one ballooned; others accept the position callout as the characteristic.

Key characteristics. If the model flags them with a PMI attribute or a note, carry that flag onto Form 3 so they get the attention they would on a 2D drawing.

One rule from 2D still holds without exception: one balloon, one Form 3 row, and your highest characteristic number should match your balloon count. Our guide to filling out AS9102 Forms 1, 2 and 3 covers that step in detail.

Where GroundControl fits

GroundControl's First Article Inspection software builds AS9102 reports from 2D drawings and CMM data today, and MBD support is on our roadmap. If you are weighing the two workflows, read MBD Inspection vs 2D Ballooning next.