How to specify C3604 Brass on a drawing

C3604 Brass is a free cutting brass with lead, the standard choice for turned parts that have to be fast to make. It is used for fittings, connectors and turned components where machinability drives the cost. This entry explains what it is, what the numbers on a data sheet mean, and what to put on a drawing.

It is written from the point of view of the buyer and the drawing office: the values that are realistic in production, the ones that cost money, and the way the result is verified. Where an industry sets the requirement, medical is used as the example: validation evidence that matches the drawing exactly.

What belongs on the drawing

A clear drawing for C3604 Brass states the function, the tolerance and the verification, and leaves the route open where the function allows it.

• The feature and its tolerance: ±0.01 mm, applied to the features that locate the part.
• The material and its condition: C3604 brass, with the certificate requirement.
• The surface finish: Ra 0.8 µm achievable directly from the tool, called out only where it does something.
• The verification: EN 10204 3.1 available, RoHS exemption noted where required, and the standard the report is written to.

Mistakes that cost money

• Using it for a drinking water part where lead content is restricted, which makes the part more expensive without making it better.
• Assuming it is as strong as steel, because it is not, which makes the part more expensive without making it better.

A workable note

Where a general note is used, say so once in the title block and keep the feature level call outs for the dimensions that matter. Take advantage of the machinability: fine finishes come free

Applications

C3604 Brass is used for fittings, connectors and turned components where machinability drives the cost, and in practice it appears most often in plumbing fittings, electrical connectors, instrument parts, valve bodies.

How it fits into a machining route

The route is fixed before the first part is cut, and it is the route rather than the individual setting that holds the result: material cost is moderate, and the cycle time is the lowest of any metal. Where a drawing calls for something the route cannot hold economically, that is raised at quotation rather than after the parts are made.

Standards, documentation and what is issued

The documentation requirement is EN 10204 3.1 available, RoHS exemption noted where required. Material is supplied against a certificate where the application calls for it, inspection results are recorded with the job, and the records are kept so that a repeat order can be compared with the first instead of being measured from scratch.

Standard dimensional inspection is the verification step. Where a customer format or a standard report is required, it is agreed before the batch starts, because a report written after the event is a report nobody can use.

Frequently asked questions

What tolerance should be specified for C3604 Brass?

±0.01 mm is realistic in production. Tightening it beyond the functional requirement increases cost without improving the part.

Which material is usually used?

C3604 brass is the usual choice, supplied against EN 10204 3.1 available, RoHS exemption noted where required.

How is the result verified?

Standard dimensional inspection, with the results recorded so a repeat order can be compared with the first.

What is the most common mistake?

Assuming it is as strong as steel, because it is not.

How long does it take and what does it cost?

A realistic cycle is very fast, with excellent chip breaking, and the cost driver is material cost is moderate, and the cycle time is the lowest of any metal.

Related capability

If you are specifying C3604 Brass on a drawing and want a second opinion on the route, send the model and the quantity. The first response is a manufacturability review with the likely risk points and a quotation, so the decision can be made on facts rather than on a price alone.

Machining, inspection and documentation are handled in one place, which is why the dimensional report and the material certificate arrive with the parts rather than after them.

Related entries

These entries sit next to C3604 Brass in the encyclopedia: 6061-T6 Aluminium, 7075-T6 Aluminium, Hydraulic Manifolds. Reading them together gives a fuller picture of how the process, the material and the measurement affect each other.