Unpleasant sounds caused by both mechanical vibrations and sound waves propagating in the air are often a real bane of owners of older vehicles. In new car models, more and more technologically advanced damping mats are responsible for noise reduction. The latter, however, are damaged during collisions or traffic accidents and must be rebuilt to restore their proper functioning.
MATS OR FOAMS?
To suppress noise caused by vibrations, soundproofing mats are used. On the other hand, airborne noise is suppressed by polyurethane foams with a sponge structure. Soundproofing mats are available in the form of self-adhesive sheets, while foams are formed by spray application.
WHAT AND WHERE TO USE
Two-component polyurethane foam is most often used in closed threshold profiles and in A, B, C pillars. Its task is to block the flow of air-borne noise in hollow closed profiles. In addition, the task of two-component foam is to reduce noise, as well as vibrations and shocks.
Foam should be carefully rebuilt when performing accident repairs. This is particularly important because its lack may, on the one hand, generate unpleasant noise, and on the other hand, e.g. result in difficult to remove window fog.
On the other hand, car covers contain various types of flexible foams (resembling products used for sealing windows). They are used to attach the door, roof, bonnet and trunk trim, as well as around the fuel filler opening, to suppress vibrations transmitted by metal parts of the vehicle. Flexible foams can also be used in places of contact of individual elements and everywhere where there is a fear of friction of their surface, e.g. between plastic elements inside the vehicle or between vibrating wires.
For silencing doors when closing (on the inside) and the engine compartment (on the cover), self-adhesive matting based on bituminous plastic is used. They are characterized by self-adhesive substrate made of special acrylic copolymers. Bituminous material is effective in damping the sound of the material and reduces the vibrations of metal and plastic.
A variation of the bituminous mats listed above are their equivalents with a special filler. How it’s working? During the final assembly, the mat is heated, which makes it plastic. It can then be adapted to deep and tight depressions, e.g. in fenders. Mats are produced in sheets of various sizes, which are then cut to the required size.