How to specify 6061-T6 Aluminium on a drawing

6061-T6 Aluminium is a heat treatable aluminium alloy with magnesium and silicon, in the T6 temper. It is used for general machined parts where weight, strength and cost have to be balanced. 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, food processing is used as the example: surfaces that clean down between production runs.

What belongs on the drawing

A clear drawing for 6061-T6 Aluminium states the function, the tolerance and the verification, and leaves the route open where the function allows it.

• The feature and its tolerance: ±0.02 mm, applied to the features that locate the part.
• The material and its condition: 6061-T6 aluminium, with the certificate requirement.
• The surface finish: Ra 1.6 µm as machined, anodising available, called out only where it does something.
• The verification: EN 10204 3.1 available on request, and the standard the report is written to.

Mistakes that cost money

• Assuming it can be welded without losing the T6 condition, which makes the part more expensive without making it better.
• Calling up a hard anodise on a part with tight tolerances, because the coating builds up, 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. Specify the temper on the drawing, not just the alloy number

Applications

6061-T6 Aluminium is used for general machined parts where weight, strength and cost have to be balanced, and in practice it appears most often in enclosures, brackets, heat sinks, machine frames.

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 low, so the process dominates. 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 on request. 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 6061-T6 Aluminium?

±0.02 mm is realistic in production. Tightening it beyond the functional requirement increases cost without improving the part.

Which material is usually used?

6061-T6 aluminium is the usual choice, supplied against EN 10204 3.1 available on request.

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?

Calling up a hard anodise on a part with tight tolerances, because the coating builds up.

How long does it take and what does it cost?

A realistic cycle is fast cutting, low tool wear, and the cost driver is material cost is low, so the process dominates.

Related capability

If you are specifying 6061-T6 Aluminium 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 6061-T6 Aluminium in the encyclopedia: 304 Stainless Steel, 17-4PH Stainless Steel, O-Ring Grooves. Reading them together gives a fuller picture of how the process, the material and the measurement affect each other.