Air spring bellow crimping process

Maybe you could coat the interior with some liquid rubber....

https://www.researchgate.net/publication/330105002_Crimping_Profile_Optimization_on_the_Air_Spring_Using_Finite_Element_Method

The bellow is crimped by a metal ring onto a plastic or metal part. The reason for the air leakage is either loose crimping or very that crimping that damages the bellow.

There doesn't seem to be any method of holding tension on the crimp sleeve....I would try to improve the sealing surface with a corrugation running around the pipe below the crimp location, or a different design for the crimping band that would hold tension...alternatively, possibly a sealant on the mating surface...what is the hose pressure design?

Move the position of the crimping from a to b; possibly by turning the crimp tool upside down.

Has the crimp tool been calibrated according to the manufacturer's instructions?

Won't you move it the opposite direction, B to A?

I'm assuming that the metal crimp was originally a smooth cylinder. It looks as though the crimp tool has formed the crimp very close to the bottom edge, where it is more likely to damage the bellows.

If the crimp was formed close to the top edge, then, damage to the material wouldn't matter, and, he could probably adjust the tool for a tighter crimp.

You could try to add a short section of heat shrink wrap (possibly adhesive shrink wrap) between the top of the bellows and the crimp.

Add a circular one piece flat band of rubber below the crimp ring.This will increase the crimp pressure without damaging the bellows.

It can be inside or outside of the bellows.

A large office rubber band may work.

Here is an example,but I don't know the diameter needed.

If the diameter reduction is increased, the plastic piston fractures, therefore anything increasing the pressure (reducing the final diameter or adding a rubber band) breaks the plastic piston. We are after finding some sort of a standard for the final crimping diameter and the make adjustments for the rest of the product parameters.

I suspect you are either using the wrong crimping tool or that the tool is worn out. Using some sealing compound (RTV silicone, rubber cement, etc.) as a gasket between the bellows and coupler might work as a "bush fix" for a repair. If your company is in the business of making these air springs then you should repair or replace the crimping tool.