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Technical guides
Connect functional features to datums, tolerances, and inspection priorities so drawing requirements are clear before quotation.
Engineering overview
A critical dimension is one whose variation can affect a defined function such as fit, location, motion, sealing, or assembly. Start with the mating interface, identify the feature and datum relationship that control it, then state how acceptance should be checked. This guide helps distinguish those requirements from general dimensions; the drawing owner remains responsible for selecting engineering limits and applicable standards.
Representative visualProcess comparison
Begin with the assembly condition, then define the feature, datum, and inspection requirement that make the condition reviewable.
| Functional need | Drawing information | Review focus |
|---|---|---|
| Part location | Datum faces, locating holes, or a datum axis. | Whether the datum structure reflects how the part is assembled and measured. |
| Fit or motion | Limit dimensions or a fit designation on the mating diameter or width. | Mating-part information, operating clearance, and surface condition. |
| Sealing | Sealing face, flatness or form control, and applicable surface requirement. | Where the seal contacts and whether finishing changes the surface. |
| Feature location | Position or another suitable geometric control referenced to defined datums. | The relationship between holes, bores, faces, and the assembly interface. |
| Inspection priority | The feature, datum, acceptance state, and any requested record. | Whether inspection matches the functional requirement and occurs before or after finishing. |
| Appearance | Identified cosmetic surfaces, finish specification, and allowed visual variation. | A separate acceptance standard from functional dimensions. |
Trace how the part locates, moves, seals, or fastens to adjacent components, then call out the dimensions that control those functions.
Datums should represent stable features that locate the part for assembly and inspection. A datum reference that does not match the functional interface can make a drawing difficult to interpret consistently.
Technical guides / Manufacturing context
Representative media supports the engineering discussion and does not document a specific customer order.
For each critical feature, connect the drawing callout to its functional reason and acceptance method. A short controlled list can help a quotation distinguish what must be verified from what is informational; it does not replace the drawing or applicable design standard.
The CAD model and drawing should describe the same design intent. A visible revision identifier helps prevent superseded requirements from being used for a quote or repeat order.
Before you request a quote
Use these answers to prepare the requirements for your part. Project details are confirmed during drawing review.
No. Apply feature-level tolerances where variation affects fit, function, or acceptance. Unnecessarily tight requirements can limit manufacturing options and add inspection effort without improving the part.
A dimension is critical when its variation can affect assembly, motion, sealing, load transfer, alignment, or another defined function. The drawing should make both the feature and its datum relationship clear.
Treat cosmetic acceptance separately. Identify the visible surfaces, finish specification, masking boundaries, and visual acceptance requirements rather than mixing appearance notes with dimensional controls.
Revise the model and drawing together, update the revision identifier, and highlight the changed requirements in the RFQ or change note. Do not rely on an email description while leaving the controlled drawing unchanged.
Ready for engineering review
Send your drawings and let our engineering team review your project.
We will provide your quotation within 24 hours after we receive complete drawings and project requirements.
Make the requirements clear
Include quantity, material, finish, critical dimensions, and any inspection requirements.
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