An aluminum bill of materials is only as reliable as the alloy, temper, and finish it names on every line, because listing "aluminum" without a grade leaves the contract manufacturer free to quote 6061 when the design actually needs 7075-T6, a mismatch that derails the RFQ timeline and the production run behind it [S1].
The aluminum BOM in practice covers raw stock, extrusions, sheet and plate, machined parts, castings, fasteners, hardware, surface treatment, and consumables, each tagged with a unique part number, quantity, unit of measure, and reference designator so procurement, fabrication, and assembly pull from the same record [S2][S5].
Core rows an aluminum BOM must carry
A complete aluminum BOM treats every line as a contract-manufacturing instruction, not a description: part number, part name, quantity, unit of measure, procurement type (make, buy, or assemble), reference designator, raw material with alloy and temper, finish specification, and cost per unit are the eight fields cited as the standard set [S5]. Listing a generic "aluminum" callout without a temper is flagged as a top-quoting error because 6061-T6, 7075-T6, and 5052-H32 behave differently in machining, anodizing, and weld repair, and the wrong choice invalidates downstream cost and lead-time assumptions [S1].
For extrusions and sheet, the BOM also has to capture profile reference or thickness, length, and any cut-to-size allowance, because extruders and service centers price by the pound or by the meter to a cut tolerance, not by the finished part [S3]. The BOM should additionally list the secondary process rows separately, anodizing, powder coat, chromate conversion, bead blast, or chemical film, each with the relevant MIL or AAMA spec so finishing capacity can be sourced independently of mill supply [S1][S2].
Aluminum alloy and temper selection in the BOM
The four alloys that dominate an industrial aluminum BOM are 6061-T6 for general machined and structural parts, 7075-T6 where higher strength-to-weight matters, 5052-H32 for sheet and formed panels, and 6063-T5 for architectural extrusions, each chosen for a specific reason that the BOM should make legible to the supplier [S1]. A 7075-T6 callout in a structural bracket versus a 6061-T6 callout changes both price and machining behavior, so leaving the temper off the row is the single most expensive omission in an aluminum RFQ.
The BOM should also record any thermal or hardness requirement on the part, because heat-treat and aging routes (T6 vs T651 vs T7351) drive both lead time and stock size, and a 7075-T651 stress-relieved plate carries a different mill price than a 7075-T6 reference [S1][S2]. For sheet, the H-temper (H32 vs H34) dictates minimum bend radius, and the BOM row needs that temper for the fabrication shop to plan brake forming without cracking the panel. The same logic applies to 6063 extrusions where T5 (air-cooled from the press) and T6 (solution heat-treated after extrusion) deliver different surface hardness and anodizing response.
Structure: single-level, multi-level, and engineering vs manufacturing BOM
An aluminum assembly is most often captured as a multi-level BOM, where the top-level assembly, such as an aluminum enclosure or ladder frame, branches into sub-assemblies, which in turn branch into individual parts, fasteners, and finish processes, mirroring the pyramid structure used to manage a 10,000-component car build [S4]. Single-level BOMs still have a role for simple subassemblies, but the moment a weldment or machined housing enters the structure, a multi-level layout is what keeps revisions and ECOs controllable [S3].
The two BOM types that matter most for aluminum work are the engineering BOM (EBOM), owned by design and reflecting the as-designed structure, and the manufacturing BOM (MBOM), owned by manufacturing and reflecting the as-built process, including plate stock cut into multiple parts, fasteners grouped by bin, and surface finish applied as a step rather than a material [S3]. Service BOMs (SBOMs) become relevant for spare-part kits and field replacements, where the consumable set, gaskets, fasteners, and touch-up anodizing dye, is listed separately so a field technician can order the right kit without pulling the full assembly drawing [S5].
Quantities, units, and the explosion step
Every aluminum BOM row must carry a quantity and a unit of measure, and the unit of measure is the field that most often breaks between EBOM and MBOM because engineering thinks in parts while manufacturing thinks in lengths, areas, or weight [S2][S3]. The MBOM typically carries both: one row for "1 ea, bracket, machined 6061-T6" and a parent row for "0.85 in x 4.0 in x 12.0 in bar stock, 6061-T6, 0.92 ft length" so that yield and scrap factors roll up correctly [S3].
BOM explosion multiplies parent quantities by child quantities down the tree and is what lets procurement convert an order for 200 welded assemblies into the right number of extrusions, weld wire, fasteners, and anodizing rack slots, and BOM flattening is the inverse process that strips the hierarchy into a single purchase list for RFQ or vendor scheduling [S3]. Both are standard functions in manufacturing ERP, and both are useless if the parent quantity or the scrap factor was never recorded on the BOM row [S2][S3].
Finishes, hardware, and the rows that quietly inflate cost
The rows that most often get left out of an aluminum BOM, and then show up as invoice surprises, are surface finish, hardware, and consumables. Type II vs Type III anodizing (sulfuric vs hard anodize) changes both thickness and color tolerance and should be its own row with the AAMA or MIL-A-8625 reference [S1]. Powder coat calls need a part row, not a note, because powder line capacity is booked separately from mill supply. Stainless or zinc-plated steel fasteners mixed with aluminum assemblies need their own BOM line so galvanic compatibility can be reviewed at the part level, and anti-seize, loctite grades, and touch-up paint belong on a consumables line that ships with the kit, not buried in the assembly drawing [S1][S5].
For sourcing, the BOM also needs procurement type: make, buy, or assemble. A 6061-T6 bracket may be "make" on a CNC cell or "buy" from a local job shop, and that decision drives whether the BOM row carries a raw material sub-line or just a finished part on a PO. The same bracket on the same drawing typically exists in both states across a product family, so the procurement type field is what lets a single master drawing serve two different BOM rows [S5].
Sourcing signals and standards to anchor
For incoming aluminum, the BOM should reference the mill standard (ASTM B209 for sheet and plate, ASTM B221 for extrusions, ASTM B85 or B26 for castings) and the UNS alloy cross-reference, because a row that says "6061-T6 plate, ASTM B209, 0.5 in x 48 in x 96 in" lets the supplier quote against a single common specification rather than guess at the certificate requirements [S1][S2]. For fasteners used with aluminum, the BOM should call out the coating or material (300-series stainless, zinc-plated steel, nylon insert) so the galvanic question is answered at the row level rather than at the field-failure level.
Trackable next signals for any engineer tightening an aluminum BOM this quarter: confirm temper is on every line, separate mill stock from finished part rows, attach an ASTM or AAMA spec to each finish callout, and run a BOM explosion against a current open order to verify scrap factors match what purchasing has been ordering. The related playbooks for raw material selection and for steel BOM structure are worth reading alongside this one; sourcing discipline in aluminum raw material sourcing guide: spec, supplier vetting, price, risk and the structural patterns in Steel BOM essentials: shapes, grades, and weights that win bids carry the same row-level rigor into adjacent material systems, and the finishing rows overlap directly with the aluminum alloy reference for any engineer checking temper and hardness data.
For the relevant spec sheets and selection criteria, see shaft key, and construction machinery and equipment.