Coil stock and finished fenestration assemblies sit at two different points on the same aluminum alloy value chain, and the July 2026 China export market shows that gap in concrete numbers: raw 6063 T5 anodized solar-frame extrusion is quoted at US $4.00-4.40/kg with a 500 kg minimum [S5], while a finished Low-E double-glazing bi-folding door carries an FOB of US $280/square meter with a 100 m² minimum [S1].
Window and door sets span a wider band — Australia-style aluminum awning windows list at US $90-100/m² and black aluminum sliding doors at US $80-100/m² on the same trading-company listing [S4] — confirming that the finished-product value is roughly two orders of magnitude above the input billet when measured per kilogram.
Product Forms, Alloy Grades, and MOQ Anchors
Coil and extrusion stock is sold by weight with MOQs from 500 kg upward, while aluminum window door systems are sold by area with MOQs starting at one square meter on the trading side and 100 m² on the audited-supplier side [S1][S4].
Zeyi Aluminum's July 2026 catalog lists a 20-inch-out-diameter aluminum irrigation pipe at US $2,000-3,000/ton (1-ton MOQ) and 6063 T5 anodized solar panel frame extrusions at US $4-4.4/kg (500 kg MOQ), the 6063 T5 temper being the dominant architectural-extrusion grade across the surveyed Chinese mills [S5].
Wasin Aluminium runs three factories in Foshan covering approximately 20,000 m², producing hardware accessories, window-door-series profiles, finished windows, and doors for non-architectural-industry use — a vertical integration that compresses the coil-to-frame handoff in-house [S6]. Kunshan Jiadihao's profile catalog is built around ISO 9001-certified Construction & Decoration output, with registered operation since 2012 [S3].
Surface Treatment, Hardware, and Conversion Cost Layers
Surface conversion on Chinese window/door lines typically follows a five-step route — protective tape, iron-pallet fixing, plastic-belt tie-down, PE film wrap, and air-bag interlayer — with finish options covering anodizing, sand blast, powder coating, electrophoresis, and wood-grain transfer [S8].
Dobestbuilding's finished window and door sets are specified with South Bright Glass (Australian Standard AS 2208), GY aluminum profiles, AkzoNobel powder coating, and Doric / SIEGEN hardware, with the entire factory operating under ISO 9001 and AS 2047 certification [S2]. Each of those value-adds (Australian-spec glass, branded hardware, third-party powder) adds a documented cost layer that does not exist on a raw aluminum coil quotation.
Nonfemet International (registered 2009) extends the same base alloy into auto/motorcycle, electrical/electronics, furniture, health/medicine, and transportation segments, illustrating that 6063-family coil stock feeds at least seven downstream categories beyond fenestration [S7].
Selection Criteria: When to Buy Coil, When to Buy the Door
Specifying a coil makes sense when the buyer runs their own extrusion, fabrication, and finishing line, or needs a non-architectural form (irrigation pipe, solar frame, auto trim), and is willing to commit to 500 kg to 1 ton per SKU [S5].
Specifying a finished system window door makes sense for construction buyers who need hardware, glass, certification, and warranty bundled: Dobestbuilding publishes a 10-year warranty on its casement, sliding, folding, and sunroom lines [S2], and audited mills like Guangzhou Homi run at a 5.0/5 platform rating with ≤15-hour average response time [S1].
For non-load-bearing partitions and sunrooms, Dobestbuilding's eight product families — aluminum casement, sliding, frameless folding windows, sliding doors, folding doors, sunrooms, retractable fly screens, and electric aluminum roller shutters — cover the residential scope in one supply contract [S2].
Comparison Matrix: Coil vs Door on Four Decision Criteria
Cost per kg: aluminum coil/extrusion stock lands at US $2.00-4.40/kg on 2026 China FOB [S5]; finished door sets at US $80-280/m² depending on glazing and hardware spec [S1][S4]. Converting: a typical 6063 T5 door profile weighs 1.5-2.5 kg/m, so a US $4/kg coil plus conversion can still undercut a US $80/m² finished assembly — but only for a buyer with their own line.
Lead time and MOQ flexibility: coil at 500 kg-1 ton MOQ suits bulk OEM; door sets at 1-100 m² MOQ fit project-sized orders [S1][S4][S5]. Certification scope: coils ship as raw material with mill test reports; door sets ship with ISO 9001, AS 2047, and AS 2208 documentation where the finished supplier is qualified [S2]. Warranty: coil warranties are typically limited to grade conformity; Dobestbuilding publishes a 10-year product warranty on finished window/door lines [S2].
Limitations, Failure Modes, and Quality Audit Anchors
Coil stock has a documented failure mode of batch-level alloy drift — chemistry variation between heats that the extruder must catch at the press, not the project site — and buyers should pin a mill test report per heat on every PO.
Finished door sets have their own failure modes: thermal movement at the glass-to-frame interface, hardware corrosion on coastal sites, and powder-coat fade — each addressable by named-component specification rather than generic grade.
For buyers comparing audited versus trading-company channels, the July 2026 snapshot shows audited manufacturers carrying 5.0/5 platform ratings with sub-15-hour response windows [S1], while trading companies (e.g., Deqing Roomeye, 5 employees, established 2010-05-11) compete on FOB spread rather than production control [S4]. For buyers integrating fire door and fire-rated door lines into the same envelope, the coil-first spec model breaks down because fire certification is a system-level test on the finished assembly, not on the profile.
Trackable next signal: any of the audited mills (Homi, Jiadihao, Wasin, Dobestbuilding) publishing a 2026 H2 price refresh on FOB Asia-to-Australia or Asia-to-Europe routes, since the current data set pins most of the volume on China-domestic plus Oceania export channels [S1][S2][S3][S6]. A second watch item is whether the 6063 T5 solar-frame extrusion price band of US $4-4.4/kg [S5] holds against any Q3 billet index move.
See also our earlier report, Additive Manufacturing Process Control: Sensor Stack, PLC Loop, and Digital-Twin Feedback.