Plastic to aluminum tolerance fit..

Hello, so I have a very simple question for those who have experience making plastic on metal fits:

I have an frame with aluminum square tube rails (1.5”x1.5”) joined by plastic corners. The frame is not expected to be exposed to high heat but will be stressed and relieved continually.

What is your best estimation for the tolerance between the (machined) plastic corner inserts and the (extruded) aluminum tubing for a good fit (somewhere between a perfect fit and a very light hammer tap?


Thank you!

Plastic is a general term. Which is the plastic used? What is the design of the component? A polymer like UHMWHDPE can have a very long fatigue life. However, its mechanical properties are poorer than other engineering polymers. What is the stress seen by the joint?
Unless more details are available it will be difficult for members to suggest solutions.