1. Identify the controlling files
Send the current finished-part drawing and, where available, the 3D model and casting drawing. Record their revisions and tell the supplier which document governs if information differs. Do not silently combine dimensions from a previous revision with a newer model. Highlight unresolved differences so the quotation can list its assumptions.
2. Mark functional interfaces
Identify bearing seats, mounting faces, locating features, sealing faces or other interfaces relevant to your part. Retain the datum scheme and geometric requirements defined by the designer. If purchasing only has an assembly model, ask engineering for the component acceptance definition rather than assigning a blanket precision requirement to every surface.
3. Define the machining and finishing boundary
State which surfaces are to be machined and which remain as cast. Include threads, inserts, plugs and other supplied items where applicable. Identify the required finish and any protected interfaces. If the buyer will perform further machining, describe the delivery condition and the requirements for that intermediate stage.
4. Specify what the inspection record must show
Agree the features to report, the drawing revision, the sample or batch identification and the acceptance criteria. Ask for the intended inspection approach to be stated where a feature is difficult to verify. A report titled dimensional inspection does not, by itself, confirm that every functional interface has been checked.
5. Compare equivalent quantities and delivery scope
Request separate visibility of tooling, sample work and repeat-production pricing. Give the number of different part numbers, the quantity per part number and the expected ordering pattern. A family of similar housings should have its differences recorded; do not assume that a price for one geometry applies to every variant.
Example enquiry for a finished housing
Please quote the finished housing to drawing [number / revision] and model [revision]. Controlling document: [file]. Critical interfaces: [drawing feature references]. Supply includes [machining / finish / inserts] and excludes [items]. Please state the proposed dimensional report scope, sample approval sequence and separate tooling and production costs.
Information to collect
- Finished-part drawing, model and casting drawing revisions
- Controlling document and unresolved conflicts
- Functional interfaces and drawing datum references
- As-cast / machined / finished supply scope
- Material specification and required records
- Feature-level inspection and acceptance requirements
- Part numbers, quantities, variants and annual forecast
- Tooling ownership requirements and delivery destination
Put the information to work
Send the available files and identify open questions. Keep confidential customer information out of public posts; share authorised project files directly for review.
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Further reading: SFSA information for steel-casting buyers. This JK Casting worksheet organises purchasing information; application-specific design and acceptance requirements must come from the approved project documents.