Three facts that decide this page
- 5052 is the usual choice for formed covers and brackets because it forms better than 6061 at the same thickness, while 6061 is specified where strength or machinability matters more than formability.
- Seven-tank pretreatment, a 16 ft × 16 ft shot blast chamber, an 18 ft × 14 ft powder booth and a curing oven sit in the same plants as fabrication, so a part is not shipped out and back for coating.
- The natural oxide layer must be removed and replaced with a conversion coating suited to aluminium before powder. Aluminium expands more than steel when heated, so large thin panels can show telegraphing over welds or dents. Where the coating is architectural, the powder and pretreatment should be specified together against the exposure category.
What changes when you powder coat aluminium
The natural oxide layer must be removed and replaced with a conversion coating suited to aluminium before powder. Aluminium expands more than steel when heated, so large thin panels can show telegraphing over welds or dents. Where the coating is architectural, the powder and pretreatment should be specified together against the exposure category.
The commercial consequence is that aluminium is priced on its own material line, not blended into a steel rate. Material grade, thickness, tolerance and finish are quoted separately from conversion, so a change of specification is visible in the price.
Tolerance, edge and finish
Ganesh quotes to the drawing first and to ISO 2768 general tolerances where the drawing is silent. For aluminium powder coating, the practical starting points are in the table below. They are starting points, not a guarantee: the part geometry, thickness and fixturing decide what can actually be held, and the quotation states the tolerance offered.
How Ganesh runs this route
Film thickness is specified and measured, not guessed: 60–80 µm is the usual architectural range and 80–120 µm is used where impact or corrosion exposure is higher. Aluminium needs a dedicated pretreatment; a phosphate line built for steel will not give the same adhesion, and chromate-free conversion is the practical route for a mixed-material shop. The route is quoted as one sequence so the customer does not have to coordinate a cutter, a former, a welder and a coater.
When powder coating is the wrong route for aluminium
Coating is the wrong finish where the aluminium is specified for conductivity, heat transfer or a visible mill finish. Anodising is the alternative for a hard, conductive-friendly surface.
A manufacturability review before quotation is the cheapest place to find this out. Send the drawing, material, finish and annual quantity and the review comes back in writing.
Typical parts
- Enclosure covers
- Canopy panels
- Architectural trim
- Equipment housings
Decision rule: when to choose powder coating
Specify powder where you need a durable, single-coat finish with good impact resistance and a wide colour range. Specify wet paint where the part needs a very thin film, a metallic or special-effect finish, or a touch-up-friendly surface. Specify blasting plus a zinc-rich primer plus a topcoat where the service environment is C4 or C5 under ISO 12944 and the part cannot be re-coated in service. For aluminium the practical constraint is the oxide layer and the alloy temper: pretreatment, bend radius and weld procedure all change relative to steel, and the drawing needs to name the alloy, not just the word aluminium. Aluminium is where the alloy decision matters as much as the process decision: a part specified in 6061 T6 that really needs 5052 will be quoted twice and made badly once.
What to put on the drawing
State the powder type, the RAL or approved sample, the gloss level, the film thickness range, the masking requirement and the tests expected: adhesion to ISO 2409 or ISO 4624, and salt spray to ISO 9227 with the hours stated. Say what must remain conductive. A coating specification without masking and DFT is a colour request, not a specification.
Quality evidence and inspection
DFT is measured on the production part, adhesion is checked on a sample, and colour is compared against the approved standard under a defined light source. Cure is verified against the powder supplier's window. Coating records sit with the batch, and the pretreatment chemistry is monitored per shift.
What drives the cost
Cost splits into pretreatment, powder, masking, rack loading, cure and inspection. Pretreatment is priced by area and batch; powder by area and film thickness; masking by feature count. A heavy assembly can cost more to cure than a larger, thinner panel of the same area, because oven time follows mass. On aluminium, material is quoted as its own line at the prevailing rate for the grade and thickness, so a change of specification is visible rather than hidden in a blended rate.
| Specification | aluminium powder coating | Ganesh limit or note |
|---|---|---|
| Grades | 1050, 5052 and 6061 to ASTM B209 / IS 737 | Grade per drawing |
| Thickness | 0.8–6 mm sheet; cut to 10 mm plate | Seven tank: degrease, rinse, derust, phosphate, rinse, passivate, dry |
| Tensile / property | 110–310 MPa depending on alloy and temper | 2.70 g/cm³ density |
| Alloy and temper | 1050 H14, 5052 H32, 6061 T6 | 5052 for forming, 6061 for strength |
| Bend radius | 0.8–1.5 × thickness typical | Tight radii crack on 6061 T6 |
| Laser cutting | Fast, high reflectivity | Clean nozzle and correct pierce height |
| Powder coating | Seven tank: degrease, rinse, derust, phosphate, rinse, passivate, dry | Chemistry monitored per shift |
| Tolerance basis | ISO 2768-m unless drawing states otherwise | Critical features inspected |
| Finish | Etch or conversion pretreatment, then powder coat where specified | Specified per part |
Sources and review
- ASTM B209 — Aluminium and aluminium-alloy sheet and plate · reviewed 2026-11-03
- IS 737 — Wrought aluminium and aluminium alloy sheet and strip · reviewed 2026-11-03
- ISO 2768-1 — General tolerances · reviewed 2026-11-03
- ISO 12944 and aluminium conversion pretreatment · reviewed 2026-11-03
Combines Ganesh machine limits (Seven tank: degrease, rinse, derust, phosphate, rinse, passivate, dry) with aluminium grade and property data. The "what changes" section is written for this material–process pair and is not reused on another page.
Send the drawing and we will check the route
Material, thickness, tolerance, finish and annual quantity are enough for a manufacturability review. Tooling is quoted separately from the piece price.
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