A specification for a turned brass component tells the supplier exactly what to make and how you will judge it. It combines a dimensioned drawing with written requirements for material, finish, tests, inspection and packing.
Anything you leave out, the supplier will decide for you. A clear specification gives better quotes, fewer samples and fewer disputes.
The drawing
- Use a current drawing with a part number, revision letter and date.
- Give every dimension with its tolerance, and refer to a general tolerance standard such as ISO 2768-m for the rest.
- Mark critical dimensions clearly, and add geometric tolerances such as concentricity or runout where the function needs them.
- Give the full thread designation and class, such as G 1/2 or M8 x 1.25-6g.
- State surface finish as an Ra value where it matters, such as on sealing faces.
- Show chamfers, edge breaks and whether sharp edges are allowed.
- Say whether dimensions apply before or after plating.
Material and finish
- Name the alloy and its standard, such as CW614N to EN 12164 or C36000 to ASTM B16, as explained in brass alloys explained.
- State any lead limits or DZR requirement that applies in your market.
- Ask for a mill test certificate with each rod lot.
- Give the plating type, minimum thickness on significant surfaces, test method and corrosion test, if any.
- Describe the required appearance, with a reference sample where colour or polish matters.
Quality and testing
- Require a first article inspection with a full dimensional report for new parts.
- Set the inspection plan, including which tool checks each critical dimension and the sampling plan for each lot.
- List tests such as pressure or leak tests, salt spray, plating thickness and alloy composition.
- Set cleanliness requirements, such as no chips, oil or burrs in holes and threads.
- Require written notice before any change of material, process, machine or subcontractor.
Packing, marking and documents
- Give the quantity per bag and carton, the bag type and any VCI or desiccant requirement.
- Specify labels with part number, revision, quantity, lot number and date.
- List the documents needed with each shipment, such as inspection reports, test reports and certificates.
Keep it controlled
Give the specification its own revision number and reference it on every purchase order. Keep a signed copy with each approved sample, so both sides can check the same reference later. When you change it, issue the new revision to the supplier and confirm which orders it applies to. For the commercial terms that sit around it, see what an engineering purchase contract should include.
Next step
We review specifications with you, find and audit manufacturers, and inspect against your drawing. To turn your drawing into a full specification, book a free sourcing review.