Скачать или смотреть How to remove squeaking noise on a frame backpack

Remove squeaking

Squeaking is a common problem when carrying a heavy load in many backpacks, especially backpacks with a frame. Avoiding squeaking is therefore a very high priority when developing a new Vorn backpack.
If you despite this are still experiencing a noise, the solution is simple – some paraffin wax(candle wax)

Technical explanation:

The reason why parts in a backpack could squeak is called slip-stick friction. This can be described as when two surfaces under load alternate quickly and continuously between sliding and sticking to each other.
There are mainly two solutions to avoiding slip-stick friction – increasing or decreasing friction.

Increasing friction so the parts will not move. On VORN products you will notice some areas of rubberized Hypalon textile in areas where increased friction is needed

Decreasing friction so the parts can slide without sticking. The main area where reduced friction is needed is on the two vertical fiberglass rods where the load is transferred from the frame to the carrying system. The rods are covered in a black 1,0 mm thick layer of HDPE polymer - which has a very low coefficient of friction. Sometimes even the HDPE needs a bit of lubrication to reduce the friction even further.

What causes the noise?
The reason why a backpack as a product is especially exposed to making unwanted sounds is that the force distribution through the construction is complex and it consists of a variety of different materials. The most common cause of the problem is elastic materials under tension fastened to rigid materials. These could build up potential energy until the forces overcome the friction holding it in place relative to the rigid material and the potential energy is released as sound.
Picture a piece of webbing carrying a load hanging from a horizontal frame element. When you are walking through the terrain your sideways movement will make the piece of webbing want to move sideways as well along the frame element. Since it is under tension it will stay in place until the sideways forces overcome the friction between the webbing and the frame, the webbing will then jump sideways releasing potential energy as an audible “click”. It could even make a continuous squeak due to so called slip-stick friction. Slip-stick friction can be described as when two surfaces under load alternate quickly and continuously between sliding and sticking to each other.

There are mainly two solutions to this problem: stop parts from moving by changing the geometry or increasing the friction, or make the parts slide easier by decreasing the friction.

On especially the external vertical black rods on the EV-frame it’s impractical to keep parts from moving slightly during use, so the friction is reduced by covering the rods with a 1 mm thick layer of high density polyethylene. HDPE has a high enough yield strength to handle the forces, and it has a very low coefficient of friction. However sometimes an even lower coefficient of friction on the rods is necessary to avoid the webbing from sticking to them under load - and some lubrication is needed.

Lubrication:
The best option we’ve found is paraffin wax, which is a simple answer to a surprisingly difficult question. Most lubricant are not suitable for plastics since both the base chemistry it is made of, and the additives in it, may degrade the plastic over time (HDPE rods, PA webbing and PES textile).
The most common lubricant for plastics is silicone based oils and greases, but unfortunately they do not give a satisfactory result for lubricating the HDPE rods. A number of synthetic, mineral and natural oils, greases and waxes were considered. The best choice was paraffin wax since it does not damage these plastics, and it will stay in place over time in the relevant temperature range. It is also easily available.