Who this is for: Technical managers and businesses commissioning the design of a mechanical component or assembly.
Asking for the CAD files leaves important questions unanswered when you commission mechanical design. A model can describe shape without defining materials, functional surfaces, purchased components or inspection requirements. The handover package should reflect who will use it and the decisions those people need to make.
A supplier quotation, a prototype order and a production release require different levels of information. State the purpose of each delivery so that a preliminary drawing is not mistaken for an approved instruction to buy material or start machining. That distinction should remain visible when documents leave the design team.
Identify the people who need to use the design
Purchasing needs an unambiguous description of what to request. Manufacturing needs the correct configuration and acceptance characteristics. Assembly staff need to identify parts, orientations and sequence. Quality staff need to connect a measurement to a requirement. A single file does not necessarily provide everything each group needs.
List recipients, readable formats and revision-management arrangements in the initial brief. Agree whether the business will receive editable native files, neutral exports or both, together with the intended usage rights. Ownership and reuse should be addressed in the engagement terms rather than assumed. Also identify who can resolve technical questions when a supplier finds a discrepancy between documents.
Build a consistent technical package
Geometry and manufacturing information can be shared between models and drawings or managed through model annotations when everyone involved can read them. Autodesk’s documentation describes this model-based definition approach. The practical choice depends on the recipients’ tools and working methods, rather than the designer’s preferred format alone.
Whichever approach is chosen, establish which information takes precedence if documents disagree. Different materials in the bill of materials and the drawing cannot be resolved by a machinist’s guess. A cross-document consistency check matters as much as the completeness of each deliverable. The package should make missing decisions visible, rather than hiding them behind a visually complete model.
Scroll horizontally to see every column.
| Deliverable | Information to make explicit |
|---|---|
| Part model | Identifier, revision, units and configuration |
| Drawing or annotations | Functional dimensions, material, finish and inspection references |
| Assembly | Component relationships, positions and assembly access |
| Bill of materials | Part numbers, quantities and purchased-component references |
| Revision register | What changed and which version may be used |
References: Autodesk — About 3D Annotation and Model-Based Definition
Make the information that controls function visible
A critical dimension affects a fit, movement, alignment or required performance. Specifying high precision everywhere does not replace functional reasoning. Identify which interfaces must work together and how the result will be inspected, considering the intended manufacturing process rather than assigning requirements without checking their implications.
An interference check is useful for an assembly but is not a complete assembly review. Tool access, fastener insertion, cable routing, maintenance space and the real order of operations also need consideration. Define which of these checks belong in the commissioned work. A general promise of a fully checked design is much less useful than a named review with stated inputs and recorded findings.
Control the handover and subsequent changes
Include a document list with revision, status and unresolved questions. Distinguish a quotation version, a prototype version and a release for the agreed manufacturing purpose. A folder containing files named final and final2 makes it difficult to establish what was actually ordered, particularly when several suppliers are involved.
When a component changes, identify affected documents, purchased parts and existing commitments. Supplier discussions should reference the same revision that incoming inspection will use. Before replacing a distributed file, establish who authorises the change and how any parts already made will be treated. This makes the commercial impact of a revision visible alongside the technical improvement it introduces.
Before commissioning mechanical CAD work
- State whether the delivery supports quotation, prototyping or production.
- Agree native files, exchange formats and readable documentation.
- Identify critical interfaces and available design information.
- Define the bill of materials and purchased-component information.
- Name who approves revisions, deliverables and scope changes.
Common questions
Does a STEP file always replace a technical drawing?
No. It can transfer geometry, but you must establish which manufacturing and inspection information is included and readable by the recipient. Materials, tolerances, finishes and instructions need to be communicated explicitly in the agreed package.
Can existing drawings be the starting point?
Yes, after checking their source, usage rights, revision and correspondence with the actual product. Missing or unreliable information should be identified before estimating the update work.
Sources and further reading
Apply this to your project.
Tell us the purpose of the design, your available file formats and who will use the documents. We can define a practical technical handover for your project.
Discuss your product development