We are manufacturing 10mm thick aluminium plates that are machined to a flatness of 0.025mm (25µm). The alloy is aluminium 6061-T6. A colleague has a theory that even if the flatness is within spec right after machining, it could change over time due to creep or stress relaxation and become out-of-spec at a later date. Is that actually possible? I'm dubious.
Gareth, Difficult to be precise without more details but generally creep in aluminium comes into play at higher temperatures. Using a wrought product such as 6061-T6 I would say the biggest challenge will be to get it flat within 0.025 in the first place! The plate can be ground quite easily, but generally removing the "skin" creates an inbalance in the internal stresses of the material leading to it bending when the clamps are released. This is why aluminium tool plate is generally cast raher than wrought - fewer internal stresses. If you are still concerned, let me know temperature and approx stresses and I will see if I can be more specific Steve
