Guide
What Should a Technical Data Package for Outsourced Machined Parts Include?
A technical data package for outsourced machined parts is the controlled set of files and statements that lets any competent shop make, inspect, pack and re-order the part without a phone call: the drawing, the matching model, the material and finish specifications, a revision log, an inspection plan, sample information and packing instructions.
By Saola Manufacturing engineering team · Published · Updated
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What is a technical data package, and why borrow from MIL-STD-31000?
A technical data package, or TDP, is a defined bundle of technical documents that describes an item well enough to buy or support it. MIL-STD-31000 is the best-known specification of how to build one, and its structure is a useful checklist even for commercial work.
MIL-STD-31000 is the US Department of Defense standard practice for technical data packages. Its first release dates from 2009, and the listing shows later revisions A (2013) and B (2018) (EverySpec MIL-STD-31000 listing, 2018). It describes a TDP as composed of one or more TDP elements and related data management products, lets the buyer choose the level, type and elements according to the need for technical data, and states that all requirements are subject to tailoring.
A defense-acquisition summary lists what such a package typically holds: models, drawings, associated lists, specifications and standards, together with performance requirements, quality assurance provisions and packaging details, defining the physical and functional characteristics of the accepted configuration (AcqNotes, 2026). Those are exactly the things a second supplier needs, so the useful borrowing is the idea of a defined, versioned baseline and the explicit choice of what to include.
A commercial package does not need government forms or data item descriptions. It needs the same discipline: every item identified, every item at a known revision, and no reliance on what someone remembers saying. The tailoring is yours to make, which is why the following sections focus on what to include for machined parts and what to leave out.
Which documents belong in the package?
The drawing, a matching model, material and finish specifications, an inspection plan, a revision log, sample information, packing and labeling notes, and a one-page index that lists them with their revisions.
The table maps defense-package concepts to what a commercial machined part needs. The commercial column is this guide’s own adaptation rather than a requirement of the standard.
| Package element | Concept in defense TDPs | Commercial machined-part equivalent |
|---|---|---|
| Index and revision baseline | Defines the accepted configuration | One-page release index: file names, revisions, release date, who released it |
| 2D drawing | Drawings | Dimensioned drawing with tolerances, general tolerance block, material and finish callouts, title block revision |
| 3D model | Models | STEP file at the same revision, with a statement of which governs if they differ |
| Lists and specifications | Associated lists, specifications, standards | Material specification and form, finish specification, special-process list, referenced standards with edition |
| Quality provisions | Quality assurance provisions | Inspection plan with characteristic numbers, method, gauge, sampling and records required |
| Packaging data | Packaging details | Packing method, protection, label content, quantity per carton and per pallet |
| Reference sample | Not described in the sources reviewed | Golden or limit sample information, if any, and who holds it |
How should the drawing, the model and the revision log work together?
Give them the same revision, say which one governs, and log every change with a short description and the first lot it applies to. A second supplier then cannot start from an old file without it being obvious.
ASME Y14.41 sets out requirements for preparing and revising digital product definition data, and adds exceptions to other ASME standards when digital data sets are used (ASME Y14.41 listing, 2026). Whatever practice you follow, make the governing source explicit on the drawing: for example, a note that the 2D drawing governs where it differs from the model, or the reverse. Most machined-part disputes about files are not about errors but about two files that disagree and nobody saying which wins.
Name files with the part number, revision and format, and put the revision in the title block as well. Keep a revision log in the package with the date, the change, the reason in a sentence and the first lot or date at which the change applies, so that the old and new versions are never both in production. When a revision changes only a note, say so; when it changes a feature, say which characteristic number it affects.
Release the package as one dated set instead of sending single files by email over time. The guide on STEP file versus 2D drawing covers the quoting stage, and build-to-print responsibility explains why the drawing needs to be complete before the supplier makes it.
What should the inspection plan and sample information say?
A numbered list of the characteristics to be checked, the method and gauge for each, the sampling, and the records the supplier must keep. Number the drawing the same way so the plan and the print can be read together.
A package that serves a second supplier needs a plan that is independent of the first supplier’s habits. Give each characteristic a number that appears on a ballooned copy of the drawing, mark which are critical, say how each is measured, and say what records you want back with each lot: dimensional results, material certificates and process records. The guides on ballooned drawings and inspection reports and critical characteristics show how to set this up.
Sample information belongs in the package too. If a golden sample or limit sample exists, state what it represents, which features it is valid for, who holds it and how it is returned. The guide on golden and limit samples explains the practice. For the first lot from any new supplier, require a first article report against the numbered plan, described in the guide on first article inspection with an overseas supplier.
Finally, add the packing and labeling notes: how parts are protected from each other and from corrosion, what is on the carton label, and the quantity per carton and per pallet. The guide on VCI packaging for ocean freight is a starting point for steel parts.
What should you leave out of the package?
Design intent and analysis you do not want copied, other customers’ information, cost data, and anything unreleased. A package defines the part, not the product around it.
Leave out the reasoning behind the design unless the supplier needs it to make the part correctly. A supplier needs to know that a bore is a sealing surface so it can choose the finish, but it does not need the stress analysis. Leave out assembly drawings that show your product, unless a mating fit requires a section of it. Leave out other suppliers’ names, prices and quality history, and anything that belongs to another customer, including drawings of a similar part that you are not authorized to share.
Also leave out working files. Native CAD with history trees, draft revisions and redlines belong in your system; the package should contain released outputs only. If you want the supplier to keep the package confidential, put that in the order terms or a separate confidentiality agreement rather than relying on a watermark.
How do you test that a second supplier could repeat the part?
Hand the package to someone who has never seen the part and ask them to write a quote assumptions list and a first-article plan from it. Every question they ask is a gap in the package.
This cold-read test costs an afternoon. Pick an engineer or a shop contact outside the project and give them only the released set. Ask them to name the material and the form of stock, list the operations they would use, identify the three characteristics they expect to be hardest to hold, and list the questions they would send the buyer. Close each question by changing the package, not by answering by email.
Run the same test whenever you change supplier or revision. The aim is that a new shop, a new engineer or a re-quote two years later produces the same part from the same file set. It is also a reasonable standard for a package sent to Saola for CNC turning or CNC milling quotes at its lead CNC plant: send the set through the quote form and include the release index.
Frequently asked
Do I have to follow MIL-STD-31000 for commercial parts?
No. It is a defense standard practice and states that its requirements are subject to tailoring. Use it as a checklist and keep only the elements that a machined part needs.
Is a STEP file enough without a drawing?
Usually not. A model carries geometry but not tolerances, material, finish or inspection requirements unless those are defined in the model data under a stated practice. Send the drawing too, and state which governs.
How often should I re-issue the package?
Whenever a controlled item changes. Re-issue the whole set with a new index and revision log, so the supplier never works from a mix of old and new files.
Should the package include the tolerance for every dimension?
Yes, on the drawing, either directly or through a general tolerance block. Tolerances not stated cannot be inspected or enforced later.
Does a package replace an RFQ?
No. The RFQ asks for a price and states commercial needs; the package defines the part. Send the package with the RFQ, then re-issue it unchanged at order.
Sources
- MIL-STD-31000 Technical data packages (listing), EverySpec, 2018 revision B
- Technical data package, AcqNotes, 2026
- ASME Y14.41 Digital product definition data practices, ASME, 2026