Dear Zhao-san,
We informed several times to select tube of fiber should not be bend smaller than fiber bend limit.
Because customer can bend this tube.
That's why we requested many times.
Anyway you and we have several fiber melt issue.
The cause of this is no protection for bend limit.
On your fiber cable joint, there is much easy bending joint.
On your cabinet you should prevent the fiber to bend to the limit by some mechanical construction.
(Fiber joint portion of the LASER unit have no protection. It is not good also) If you will not have any solution, you should send a fiber cable free of charge to customer in the world when fiber cable melt.
Please check your side from this point of view for fiber bend.
Best regards,
Katsuyuki Takeuchi
NEC DS