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What to Include in a Drawing for Machined Aluminium Extrusions
Published 2026-10-21
An extrusion drawing describes the starting section. A finished-part drawing describes what must be delivered after cutting, drilling, milling or other agreed operations. Sending both helps us separate profile requirements from machining requirements and review the quotation scope.
Identify the starting profile
Include the cross-section, alloy and temper requirements, and the required cut length. If you already have the profile, state its condition and available quantity. Machining supplied material is reviewed case by case; an existing extrusion is not automatically suitable for every operation.
Show the features that control assembly
Mark hole locations, slot geometry, threads, end cuts and mating surfaces. Identify the datums from which important dimensions are measured. Distinguish dimensions controlled by the extrusion from those required after machining. Where a tolerance matters to assembly, show it on the drawing instead of relying on a photograph or a general description such as “high precision.”
Explain visible faces and the finish
Identify surfaces that will be visible in the finished product and any areas that need masking or special handling. Machining before or after finishing can change the appearance of cut edges and holes. Provide the finish requirement, colour reference and quantity per colour so the sequence can be reviewed. Appearance samples do not establish dimensional tolerances.
State the inspection requirement
Tell us which features need measurement and whether a sample or first-article review is required. If you need a particular inspection record, identify it before the scope is agreed. Do not assume that every dimension or cosmetic surface will receive the same inspection method.
Specify the delivery condition
State the batch quantity and required destination. Explain whether parts need individual protection, drawing-number labels or matched-set packing. Include a required delivery date for review; it is not a confirmed lead time until the quotation and production scope are agreed.
Machined extrusion procurement checklist
| Check | Information to supply |
|---|---|
| 1 · Drawing revision | Matching 2D drawing and 3D file revisions; flag conflicts before machining. |
| 2 · Supply scope | Extrusion only, extrusion plus machining, or customer-supplied stock for suitability review. |
| 3 · Starting material | Profile or die reference, section, alloy/temper, wall and cut length. |
| 4 · Functional dimensions | Datums and critical dimensions; distinguish extrusion tolerances from finished-part tolerances. |
| 5 · Operations | Cuts, milled slots, drilled holes, threads, deburring and assembly scope. State thread standard, depth and blind/through condition. |
| 6 · Finish | Process, colour, coating thickness requirement and visible faces. State whether dimensions apply before or after finishing, and identify masking areas. |
| 7 · Quantities | Separate prototypes, first batch, forecast and quantity per colour. A forecast is not an order or an agreed minimum. |
| 8 · Acceptance | First-article review, critical measurements, required report and the stage at which acceptance takes place. |
| 9 · Delivery | Protection, drawing-number labels, packing, destination and requested date; price and lead time subject to agreed scope. |
A short brief you can copy
Profile section: __. Finished-part drawing/revision: __. Material requirements: __. Cut length: __. Holes/slots/threads: __. Critical datums and tolerances: __. Visible faces: __. Finish and quantity per colour: __. Inspection/sample needs: __. Packing and destination: __.
Send the drawings with the brief to request a review of profile supply and secondary machining. Production through our own and partner factories is confirmed for each project. Workshop footage illustrates operations; the agreed drawings and inspection scope define your order.
Profile supply and secondary machining
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