How to specify an aluminum enclosure: a 12-point checklist for hardware teams

Why most first articles fail

Almost every failed first article we see comes down to missing information, not manufacturing error: a connector that needs 8 mm behind the panel, a board that will not slide past a boss, a gasket groove that was drawn but not toleranced.

This checklist is the one we walk through with customers before cutting metal.

1. Internal dimensions, not external

Start from the PCB and the tallest component. Add:

• 1.0–1.5 mm per side for a slide-in board (more if the board is long and the profile is bowed).
• 3 mm above the tallest component for the lid and any thermal pad.
• 6–8 mm behind panel-mounted connectors for the mating plug body and cable bend.

External size is the result, not the starting point.

2. Wall thickness

For 6063 extrusion, 1.5 mm walls are standard and 2.0 mm is available on most profiles. Going below 1.2 mm makes threads and gasket grooves unreliable. Going above 2.5 mm wastes weight and money without adding stiffness where it matters.

3. Mounting bosses and standoffs

Decide now: does the PCB screw into bosses that are part of the extrusion, or into standoffs pressed into the end plates, or float on a machined shelf? Boss height sets the internal stack-up and is the single most common thing to change late.

4. Cutout positions and datum

Give every cutout a position relative to one datum — usually the machined end face and one extrusion edge. Mixed datums are how holes end up 0.8 mm off and a connector will not seat.

5. Connector keep-outs

Draw the connector body, not just the hole. Include the latch swing, the cable exit direction and the bend radius. A USB-C port that fits the hole can still be unusable if the plug hits a fin.

6. Cable gland threads

Specify the standard (M12×1.5, M16×1.5, M20×1.5, PG7, PG9), the panel thickness at the entry, and whether a sealing washer is needed. If you are aiming for IP67, order the gland from a supplier that publishes an IP rating with the enclosure.

7. Gasket groove

For IP65 and above, draw a groove rather than a flat gasket face:

• Groove width = O-ring cord diameter × 1.25.
• Groove depth = cord diameter × 0.75.
• Corner radii at least 2× cord diameter.
• Screw spacing ≤ 50 mm on the gasketed joint.

8. Surface finish and colour

Pick one: mill finish, sandblasted, brushed, clear anodized, black anodized, or powder coated. Note where finish must be masked — sealing faces and grounding contact points need bare or chromate-converted aluminum.

9. Markings

Laser marking is cleanest on anodized surfaces; silkscreen or UV print works on powder coat. Give artwork as vector, note the marking area, and say whether it must survive solvent wiping.

10. Fasteners and assembly

Confirm screw type, thread (M3 × 0.5 is typical), torque, and whether you want captive screws. If the unit is field-serviceable, specify a quarter-turn or captive fastener now — retrofitting is expensive.

11. Environment and testing

Temperature range, IP target, vibration or drop requirement, and any EMC requirement. These change material, sealing and finish choices, so they belong in the first RFQ.

12. Volume and delivery shape

Annual volume, order pattern (one-off vs monthly releases), and whether you want kits (housing + gasket + screws + glands) or loose parts. Kitting is cheap at our end and saves you a receiving step.

Tolerances you can put on the drawing

The RFQ that gets a fast answer

Housing for 120 × 80 mm PCB, 22 mm internal height. Two M12×1.5 glands on the left end, one USB-C cutout on the right end per drawing. IP67, black anodized, laser logo on the top. 500 pcs first order, 2,000/yr. STEP and PDF attached.

With that, we can quote in a day and cut a sample in three.