Suggestions needed for Back pack straps breaking

[nylonRigging]

15 hours ago, Sharon Mallory said:

It’s just a simple backpack for my 9 year old grandson and it happened on the one from when he was 5 or 6 too. I want to make one for myself and figure out what the problem is and how to avoid it.

( Looks Like ) .. when load bearing, Is your ( 1" ) Webbing breaking and shredding the weave on your toothed friction lock-bar on the Buckle  ? .
If so it's the type- webbing your using and you need to change to different . Where Getting, and what Webbing you using ?  .. 

Nylon is strongest for friction and strength . Polyester is pretty strong and best for  UV sun damage . and definitely If you using the cheap Polypropylene webbing, It will do this in the Pic. every time .

edit add:
Also under heavy load Bering, like a main lift of heavy packs and container systems . your webbing wrapped over any friction surface for best long life . It good to run a ' chaffing strip ' under the webbing wrapped over the hardware that load is hanging from.  
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Edited August 9, 2019 by nylonRigging

[blue duck]

I might be over thinking this, but I don't use a leather needle when I work with this type of strapping. I thought it might be cutting the fibers.