To source custom aluminium machining effectively, define the part’s function, alloy and temper, critical dimensions, tolerances, finish, quantity, and inspection needs before requesting a quotation. Send a clear 2D drawing and, where available, a 3D model, then ask suppliers to identify assumptions and any features that may affect manufacturability, cost, or delivery. A complete RFQ helps suppliers quote the same requirements and reduces avoidable clarification during production. At Cornerstone, we work with buyers to turn part requirements into a practical machining enquiry.
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This guide is for engineers, procurement teams, product developers, and equipment manufacturers buying machined aluminium components. It is especially useful when you are moving from a design concept to supplier quotations, comparing offers, or revising an existing part for production. Buyers sourcing components for pallet systems, material-handling equipment, or related industrial products can use the same principles to specify brackets, blocks, rails, and other machined parts. The best RFQ is not necessarily the longest; it is the one that makes important requirements clear.
Custom aluminium machining is the production of a part to a buyer’s drawing or defined requirements by removing material from aluminium stock. Depending on the design and supplier’s equipment, operations may include milling, turning, drilling, tapping, or a combination of processes. The finished part may also receive deburring, surface treatment, or other secondary work when specified. The appropriate process depends on geometry, required features, material, order quantity, and quality needs.
Before detailing every dimension, explain what the part does and how it fits into the assembly. Identify mounting surfaces, mating components, load or movement requirements, and any features that affect fit or safety. For example, a machined pallet-system bracket may need accurate hole positions to align with a frame, while a cover may place greater emphasis on appearance and edge condition. Functional context helps a supplier distinguish essential requirements from dimensions that can be produced with standard shop tolerances.
Specify the aluminium alloy and temper when they are already defined by your engineering requirements. Commonly considered machining alloys include 6061 and 7075, but neither is automatically the right choice for every part. The material decision should account for the required mechanical properties, corrosion environment, machinability, joining or finishing needs, and cost. If you do not have a fixed alloy, state the application and ask the supplier to propose an option for engineering review rather than leaving the material open without explanation.
Surface finish should also be tied to a purpose. A finish may be selected for appearance, corrosion protection, wear considerations, or a mating interface, and the specification should identify the required treatment and any relevant areas that must remain untreated. If a cosmetic surface matters, identify the visible faces and define acceptable marks or handling expectations. Avoid requesting a finish by a broad description alone when the part has functional or visual acceptance criteria.
A supplier needs enough information to understand both the part and the scope of work. The table below shows the main RFQ fields and what to clarify. Use the numerical values only as examples of how to communicate a requirement; they are not universal recommendations or a statement of Cornerstone’s production tolerances.
| RFQ item | What to provide | Example or clarification |
|---|---|---|
| Part definition | Drawing revision, part number, and 3D model if available | Identify which file controls if the drawing and model differ. |
| Material | Alloy and temper, or permission to propose an alternative | Include any required material documentation. |
| Dimensions and tolerances | Overall dimensions, critical features, datums, and tolerances | A 100 mm overall length is a dimensional example; specify the actual requirement on the drawing. |
| Feature details | Hole sizes, threads, slots, countersinks, and edge requirements | For example, call out a Ø10 mm hole and define its position from datums. |
| General tolerance | A stated drawing standard or explicit default tolerance | ±0.1 mm can illustrate a requested tolerance, but use it only where the design requires it. |
| Finish and inspection | Surface treatment, appearance criteria, inspection scope, and records | List critical dimensions that must be verified and how results should be reported. |
| Commercial details | Quantity, delivery destination, target schedule, and packaging needs | Separate prototype needs from expected repeat orders, if applicable. |
Not every dimension needs the same tolerance. Tight tolerances can require additional process control or inspection, so identify which dimensions affect assembly, motion, sealing, or performance and which are non-critical. Use datums and clear geometric dimensioning where position, orientation, or flatness matters; a list of isolated measurements may not communicate how the part should fit. If a supplier proposes a deviation, ask for the affected feature, reason, and impact on function before approving it.
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These steps make quotation review more useful because each supplier is responding to a defined scope. If a requirement is still being developed, label it as provisional and ask the supplier to state the assumptions used in the quote. Do not treat an unconfirmed assumption as an approved design change. Keep the final drawing, quotation, and any agreed deviations aligned before production begins.
When comparing suppliers, assess whether their quotation addresses the full technical and commercial scope. Check the proposed material, machining operations, finishing, inspection, packaging, and delivery terms against your RFQ. A lower unit price may not be comparable if it excludes finishing, documentation, or a requested inspection. Ask suppliers to state exclusions and quote validity so your team can compare offers on a consistent basis.
For an export purchase, confirm the delivery destination, packaging requirements, shipping responsibilities, and documents required for your receiving process. These details can affect the total sourcing plan even when the machined part itself is unchanged. If your organization has specific quality or traceability requirements, put them in the RFQ and confirm that the supplier can address them before ordering. Do not assume that a requirement is included unless it appears in the quotation or is confirmed in writing.
Custom-machined part pricing depends on the design, material, machining time, setup, finishing, inspection, order quantity, and delivery scope. A supplier may quote different unit prices at different quantities, so provide a realistic order estimate rather than requesting a price for an unspecified volume. Ask whether separate setup, tooling, sample, or finishing charges apply, and clarify which costs are one-time versus recurring. No minimum order quantity or lead time should be assumed without a supplier quotation for the specific part and order.
Lead time should be discussed in terms of its starting point and included activities. Confirm whether the quoted schedule begins after drawing approval, material availability, or another defined milestone, and ask whether finishing and shipping are included. If the design is not final, supplier review and approval can affect the schedule. Share your required date early, but treat it as a request to be confirmed rather than a guaranteed delivery commitment.
A strong custom aluminium machining RFQ gives suppliers a controlled drawing, material and finish requirements, clear tolerances, quantity, inspection expectations, delivery information, and the part’s functional context. Use critical dimensions deliberately, request clarification on assumptions, and compare quotations by scope rather than unit price alone. This approach is relevant to industrial components, including parts used in pallet and material-handling systems, where fit and assembly requirements should be explicit. Before ordering, confirm that the quotation and approved drawing describe the same part.
To request a quotation from Cornerstone, prepare your current drawing, 3D model if available, target quantity, material and finish requirements, and delivery destination. Include any questions about tolerances, inspection, or design alternatives so we can review the enquiry against your priorities. If some specifications are not finalized, identify them clearly and request supplier feedback before approving production. A precise, well-scoped RFQ is the most practical first step toward a reliable sourcing decision.
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