| Required alloy and temper | Confirm the alloy, temper, mechanical requirements, corrosion exposure, and intended use. | Common extrusion alloys include 6063 for architectural profiles and 6061 for higher strength applications. The supplier should provide a material certificate identifying alloy and temper. | A visually similar tube can have significantly different strength, machinability, and surface performance. | Reject quotations that do not clearly state alloy, temper, and applicable material standard. |
| Extrusion press capability | Check press capacity, billet size, maximum profile envelope, wall-thickness capability, and die-design experience. | For hollow profiles, ask for a cross-section review, minimum wall-thickness assessment, die-flow analysis, and samples from comparable geometries. | Complex hollow shapes and thin walls increase the risk of distortion, tearing, weld lines, and dimensional variation. | Select a supplier that demonstrates proven capability with a similar profile, not only a suitable press tonnage. |
| Dimensional tolerances | Define outside dimensions, wall thickness, straightness, twist, corner radius, cut length, and feature tolerances. | Use a recognized extrusion tolerance standard, such as EN 755-9 or ASTM B221, and specify tighter tolerances only where function requires them. | Unnecessary tight tolerances raise die, inspection, scrap, and machining costs. | Use standard tolerances for non-critical features and tighter limits only for mating or sealing surfaces. |
| Quality management system | Verify process control, nonconformance handling, corrective action, calibration, and document retention. | A current ISO 9001 certificate issued by an accredited certification body is useful evidence, but it should be supported by process and inspection records. | Certification indicates a controlled management system but does not replace product-specific inspection. | Prefer suppliers that can show recent corrective-action examples and calibrated inspection equipment. |
| Material traceability | Confirm lot identification from billet through extrusion, heat treatment, finishing, packing, and shipment. | Request a heat or batch number, chemical composition, tensile properties, temper condition, and a certificate such as EN 10204 Type 3.1 when required. | Traceability supports compliance investigations, field issue analysis, and controlled replacement of affected material. | Do not approve production without an agreed certificate format and lot-marking method. |
| Surface finish | Specify mill finish, anodizing, powder coating, brushing, polishing, or another treatment. | For anodizing, define alloy suitability, color range, appearance limits, and coating thickness. Architectural anodizing commonly uses approximately 10–25 micrometres, depending on the specified class and application. | Surface treatment affects corrosion resistance, appearance, dimensional fit, and final cost. | Approve a production sample or boundary sample before mass finishing. |
| Inspection and testing | Confirm inspection frequency, sampling plan, gauges, testing methods, and final inspection records. | Typical controls include dimensional inspection, visual inspection, hardness or tensile testing when specified, coating checks, and random cut-length verification. | A clear inspection plan reduces disputes and identifies process drift before shipment. | Require inspection results linked to the shipment lot and drawing revision. |
| Tooling and die cost | Clarify die ownership, die-life expectations, modification charges, storage, maintenance, and replacement terms. | The quotation should separate one-time tooling charges from recurring material, extrusion, finishing, packaging, and logistics costs. | A low piece price can be misleading when tooling, setup, or redesign charges are excluded. | Compare the complete landed cost over the expected program volume, not only the first-order price. |
| Material utilization and yield | Ask how billet length, extrusion yield, front and back discard, cutting loss, and minimum order quantity are calculated. | Compare quoted weight per metre with the theoretical cross-sectional weight and request the expected scrap or yield assumption. | Yield losses can materially change the effective cost of aluminum profiles. | Use effective cost per accepted finished metre or piece for supplier comparison. |
| Lead time and capacity | Separate tooling lead time, sample approval, production, finishing, packaging, and transportation. | Request a written schedule with production capacity, planned shipment dates, holiday constraints, and recovery actions for delays. | Late profiles can delay machining, assembly, installation, and customer delivery. | Choose a supplier with realistic capacity evidence and a documented contingency plan. |
| Total cost of ownership | Include aluminum price, conversion cost, tooling, finishing, machining, packaging, freight, duties, inspection, scrap, and warranty risk. | Use a landed-cost model with a fixed quotation validity period and clearly stated assumptions for metal-price adjustments and currency exchange. | The lowest quoted unit price may produce a higher final cost after rework, freight, delays, and rejected material. | Select the supplier with the best verified value, quality risk, delivery reliability, and lifecycle cost balance. |