How to specify 7075-T6 Aluminium on a drawing

7075-T6 Aluminium is a high strength aluminium alloy with zinc as the main addition, in the T6 temper. It is used for aerospace and motorsport parts where strength to weight is the deciding factor. 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, rail is used as the example: documented welds, coatings and fire smoke toxicity compliance.

What belongs on the drawing

A clear drawing for 7075-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: ±0.01 mm, applied to the features that locate the part.
• The material and its condition: 7075-T6 aluminium, with the certificate requirement.
• The surface finish: Ra 1.6 µm as machined, called out only where it does something.
• The verification: AS9100 with material traceability, and the standard the report is written to.

Mistakes that cost money

• Using it where 6082 would do, which adds cost for no gain, which makes the part more expensive without making it better.
• Leaving it bare in a corrosive environment, because it pits, 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. Anodise or alodine any part that will see weather

Applications

7075-T6 Aluminium is used for aerospace and motorsport parts where strength to weight is the deciding factor, and in practice it appears most often in aerospace fittings, bicycle and motorsport components, mould plates, structural brackets.

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 several times that of 6061. 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 AS9100 with material traceability. 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 with a certificate check 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 7075-T6 Aluminium?

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

Which material is usually used?

7075-T6 aluminium is the usual choice, supplied against AS9100 with material traceability.

How is the result verified?

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

What is the most common mistake?

Leaving it bare in a corrosive environment, because it pits.

How long does it take and what does it cost?

A realistic cycle is fast, but with more tool wear than 6061, and the cost driver is material cost is several times that of 6061.

Related capability

If you are specifying 7075-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 7075-T6 Aluminium in the encyclopedia: 17-4PH Stainless Steel, Ti-6Al-4V Titanium, Bearing Housings. Reading them together gives a fuller picture of how the process, the material and the measurement affect each other.