Engineering & purchasing notes
A better brief.
A better starting point.
Practical checklists for preparing a machining enquiry, reviewing a quotation and handing a prototype over to production.
Prepare your RFQ
Put the files, quantities and functional requirements in one place.
Read the checklist ↘Guide 02Compare quotations
Check the complete scope before comparing the unit prices.
Read the checklist ↘Guide 03Move into production
Carry the prototype decisions into a controlled order brief.
Read the checklist ↘Guide 01 / Prepare a useful CNC machining RFQ
A useful request for quotation lets a supplier assess the same part you intend to buy. Begin with one consistent file set and make missing information explicit.
1. Identify the part and revision
Use a drawing number, part name and revision across the model, drawing and enquiry. If the model and drawing disagree, identify the issue and resolve it before production.
2. Describe the function
Explain where the part fits, what it mates with and which features affect performance. A short application note helps prioritize the questions that matter.
3. State the manufacturing requirements
- Material grade, condition and approved alternatives.
- Critical tolerances, datum references, threads and surface roughness.
- Finish, masking, color and cosmetic requirements.
- Inspection records, traceability and packaging requirements.
4. State the commercial scope
Include initial quantity, expected repeat quantities, delivery destination and target date. Distinguish a target schedule from a fixed requirement, and identify any sample approval stage.
5. Protect confidential information appropriately
If your project requires an NDA or a specific transfer method, arrange that before sharing sensitive files. Do not assume that a form checkbox creates a confidentiality agreement.
Start an enquiryGuide 02 / Compare machining quotations on the same basis
Two similar unit prices can represent different deliverables. Compare the drawing revision, material, finish and inspection scope before deciding which quotation meets the requirement.
| Compare | Question to ask |
|---|---|
| Design | Does each quotation refer to the same files and revision? |
| Material | Is the exact grade and condition included, with any records you need? |
| Process & finish | Are finishing, treatment, masking and edge requirements included? |
| Inspection | What checks and documents are supplied, and at which approval stage? |
| One-time charges | Are setup, fixtures, samples or other initial charges separate? |
| Delivery | What is the agreed schedule, destination, packaging and shipping scope? |
| Changes | How will design changes, deviations or revised quantities be handled? |
Clarify exclusions and assumptions in writing. If the scope changes, obtain a revised quotation instead of comparing it with an outdated one.
Review the inspection approachGuide 03 / Move from a prototype to a repeatable order
A successful prototype is useful evidence, but it does not automatically define the production order. Capture what was learned and turn it into an approved specification.
Freeze the approved design
Record the accepted revision and resolve any differences between the prototype and the intended production component. Include material, finish, treatment and assembly changes.
Define acceptance
Identify critical dimensions, cosmetic standards and inspection records. Agree on any first-article or sample approval step and whether production waits for that approval.
Plan the order quantities
State the first production quantity and realistic repeat quantities. Review whether the chosen process, workholding and packaging remain suitable as the order changes.
Keep a controlled reorder brief
- Approved model and drawing revision.
- Material and finishing specification.
- Inspection and approval requirements.
- Packaging and part identification.
- Approved deviations, if any.
- Contact responsible for engineering approval.
When a later change is proposed, identify it explicitly and obtain approval before manufacturing against the updated requirements.
Explore illustrative part studiesReady to put the checklist to work?
Start with your drawing, quantity and the requirements that decide whether the part is right.