What to Put in an Aluminum Extrusion RFQ: Drawing, Alloy, Tolerance and Finish

Why incomplete RFQs cost you weeks

A quotation is only as good as the information behind it. When a drawing arrives with no temper, a finish with no thickness, and a tolerance block that tightens every dimension on the sheet, the supplier has two choices: guess, or send a list of questions. Both cost time. In our experience the difference between a quote returned in one day and one that drags on for two weeks is rarely price - it is how complete the RFQ package was on day one.

This guide lists what a Chinese extrusion plant actually needs in order to quote accurately and, just as important, to make the parts the way you expect them.

1. The drawing: what the quoting engineer really needs

A single PDF is enough to start, but it must carry the right information:

• Dimensioned 2D PDF with overall width, height, and every wall thickness called out - not just the outside envelope.
• DXF or DWG of the cross-section at 1:1. This is the file we import to check wall thickness, corner radii and the circumscribed circle before quoting. A PDF screenshot forces us to redraw the profile, which introduces errors and delay.
• STEP or IGES for any profile that will be machined, tapped, bent or welded after extrusion.
• Cut length and cut tolerance, plus whether the cut face is cosmetic.
• Critical dimensions marked - the three to eight features that actually decide whether the part fits.
• Revision number and date on the drawing. We have quoted revision A many times while the buyer was working from revision C.
• The application, in one line: LED housing, heat sink, window frame, machine guard, battery tray. It tells us which alloy and temper to propose and where the risk sits.

One practical limit worth checking early: our presses handle billets from 90 mm to 254 mm and profiles up to roughly 320 mm circumscribed circle. If your section is close to that limit, send the DXF first and ask for a feasibility check before you invest in tooling drawings.

2. Alloy and temper: do not leave it to the supplier

Alloy and temper decide strength, finish quality and machinability, and they are the field buyers most often leave blank. If you do not specify, we will propose something sensible - but you should know what you are getting.

We extrude 6063, 6061 and 6005 in-house. If your drawing says "aluminum, 6000 series" and nothing else, expect a question back - and expect the price to move once the alloy is fixed, because 6061 billet costs more than 6063 and machines differently.

3. Tolerance: a general class plus the few dimensions that matter

Tightening the whole drawing is the most expensive habit in extrusion procurement. It raises the price, slows the press, and increases the reject rate - often for dimensions that do not affect assembly at all.

The better approach is two layers:

1. A general tolerance class for the whole profile, for example EN 755-9 or the equivalent national standard for your size range.
2. An explicit list of critical dimensions with individual tolerances: wall thickness, cut length, straightness, twist, flatness on a mating face, hole position after machining.

Typical values to discuss with your supplier, before any guarantee is written into a purchase order:

Ask for a first article inspection report on the first production run, and state in the RFQ which dimensions must appear in it. That single line removes most of the arguments that follow a shipment.

4. Surface finish: specify thickness, colour and which faces are visible

"Anodized" and "powder coated" are not specifications. Each needs three numbers and one decision:

Anodizing - Type and thickness: 10 micrometres for decorative indoor parts, 15 micrometres for general use, 20-25 micrometres for outdoor, coastal or handled surfaces. - Colour: clear, black, bronze, or a sample you approve. - Sealing and whether the part is anodized before or after machining - machining after anodizing exposes bare metal at every cut.

Powder coating - RAL or Pantone colour, gloss level, and a target film thickness (60-80 micrometres is typical). - Pre-treatment type, and any areas to be masked: threads, earth contacts, mating faces, holes that must stay conductive.

Electrophoresis is available as an option when you need a uniform coating on complex sections, and mill finish is perfectly acceptable for hidden internal parts - say so, and you avoid paying for a cosmetic surface nobody will see.

Finally, mark the cosmetic faces on the drawing. A visible face and a hidden face should not carry the same acceptance criteria, and the packing cost differs accordingly.

5. Quantity, lengths and packing

• Quantity per profile, plus an annual estimate. Volume drives die amortisation and the price per kilogram more than anything else in the RFQ.
• Cut lengths, and whether offcuts are acceptable.
• Packing: interleaved paper between profiles, protective film, bundles, wooden crates, and maximum crate dimensions at your warehouse. Anodized and powder coated parts should never ship loose.
• Delivery point and Incoterm (FOB, CIF, DDP), because it changes the quote structure.

6. The commercial items buyers forget

What SYHARVEST needs to quote your profile

Our Foshan plant runs eight extrusion presses from 660 to 3600/4000 tonnes, with in-house horizontal anodizing, a vertical powder coating line and optional electrophoresis, plus eight CNC machines for secondary operations. Our quality management system is certified to ISO 9001:2015 (certificate 00225Q26954R2M).

With a complete package - DXF, drawing with alloy and temper, tolerance list, finish specification and quantity - we normally reply within one working day with price, die status and lead time. Typical production timing is 5-7 days for mill finish billet, around 12 days including surface treatment, and 15-18 days including machining.

Send your drawing and tell us the application; we will come back with a quote and, where it helps, a comment on wall thickness or tolerances that could save you money before the die is cut.