When an OEM team switches from steel to lightweight aluminum components to cut assembly weight, the RFQ rarely fails on material cost. It fails on the tolerance callouts, thread finishes, and inspection expectations left vague on the drawing. A 0.05 mm shift on a machined sleeve or bushing can stop a sensor housing from sealing properly and force a rework cycle nobody budgeted for.
What Tolerance Should Lightweight Aluminum Parts Meet
Aluminum is softer than steel, so a CNC turning cycle that holds ±0.02 mm on 304 stainless will drift if you reuse the same toolpath on 6061. Buyers should call out critical fits on the drawing explicitly — say H7 or k6 for press-fit bushings — rather than leaving a generic ±0.1 mm blanket tolerance across every dimension. For thin-walled sleeves under 2 mm wall thickness, thermal growth during machining matters; a 0.03 mm allowance for post-machining relaxation keeps parts in spec after they cool on the chuck.
Weeda Precision handles drawing-based CNC turning and multi-axis machining for these tighter fits, and includes a thread-gauge check plus surface-finish measurement on every batch lot before packing. Stating the inspection-report format in the RFQ up front removes most of the back-and-forth email loop.
Which Aluminum Alloy Fits Lightweight Parts Best
6061-T6 covers most automation equipment and electronics housings where you need machinability plus moderate strength. Jump to 7075 when the part carries a bending load, like a shaft in a plastic-molding press. The trade-off is clear: 7075 chips faster and raises per-part machining cost by roughly 15 to 20 percent. For threaded inserts and copper insert nuts mounted into aluminum panels, specifying a knurled brass or bronze insert with a locked-in thread diameter saves an entire secondary weld step downstream.
On annual-volume programs, packing and packaging format moves the unit cost more than most buyers expect. A 500-piece lot in vacuum-sealed bags versus a 5,000-piece lot in bulk bins shifts logistics handling noticeably. State the packaging spec in the RFQ so the quote reflects the real handling plan from day one.
One practical move before releasing the RFQ: send a 3-D CAD file with GD&T callouts instead of a 2-D print. It cuts interpretation errors on lightweight aluminum components, shortens the sample-approval loop, and gives the machine shop a single source of truth for every tolerance zone.