ᐅ Why do some screws come loose in BILLY despite being securely fastened?

Created on: 6 Jan 2023 08:17
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nau-se
Hello everyone,

I have a specific question that has been on my mind for some time while assembling my BILLY bookshelf: Why do some screws come loose over time even though they were installed very firmly and correctly?

I have noticed that especially the screws that should be very tight tend to loosen after a few weeks, even though I followed the recommended torque during assembly and there is no excessive play.

I would like to understand which mechanisms or material properties might be involved here, whether the type of screws themselves, assembly errors, internal stresses in the shelf, or possibly environmental factors like temperature or humidity could contribute to the loosening.

Does anyone have experience with this issue or know the technical background as to why screws in BILLY bookshelves do not stay securely fastened in the long term despite proper assembly?

Thanks for your insights!
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draleo
6 Jan 2023 13:07
nau-se schrieb:
What mechanisms or material properties can cause screws in BILLY shelves to loosen despite proper assembly?

It should also be noted that BILLY shelves with typical fasteners often allow only a limited screw-in depth. The combination of shallow screw depth, dynamic loads (for example, from handling the shelf), and the structure of engineered wood reduces the friction between the screw and the material.

Furthermore, cyclic loads on statically unsupported constructions have a negative effect on holding strength. This can be prevented by retightening, using screw locking methods, or periodically checking the screws.
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Vinlen
7 Jan 2023 08:47
The optimal solution is to check the screws again after installation and tighten them if necessary. Alternatively, fine-thread screws can also help, as they provide better grip in the wood-based material.
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gasidney
7 Jan 2023 09:23
There is also the option to use special wood screws with a sealing layer or anti-loosening coating. These prevent loosening without much effort.
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bupar
7 Jan 2023 10:05
draFrederi schrieb:
Tip: Thread lockers or washers provide more grip

Washers are only somewhat effective with particleboard, as they don’t strengthen the material. Thread lockers or adhesives are more effective, ensuring a secure connection without damaging the screw.
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nau-se
7 Jan 2023 12:17
Thank you for all the detailed tips and explanations here!

In summary, I see that the main issues are related to the particleboard material and its limited screw insertion depth, as well as dynamic loads. I will definitely try using threadlocker or anti-loosening coatings during the next assembly. I will also include regular retightening as part of my maintenance routine for the shelving unit.

If anyone has specific recommendations for reliable screw-locking products for BILLY shelves, I would be very grateful!