Application guide
Nonwoven for sound insulation and absorption
Sound insulation is an airflow problem before it is a weight problem. A fabric that blocks air blocks sound, but it also traps moisture and heat, which is why automotive and building specifications balance absorption against ventilation.
At a glance
Specification at a glance
| Property | What it controls | Typical range | Test |
|---|---|---|---|
| Basis weight | Mass per area, low frequency absorption | 80 to 400 gsm | Cut and weigh |
| Thickness | Loft and absorption peak | 2 to 20 mm | Dial gauge under load |
| Airflow resistance | Balance of absorption and ventilation | Grade dependent | Air permeability test |
| Fibre type | Durability, fire behaviour, cost | PET, PP, blends, recycled fibre | Material declaration |
| Fire performance | Compliance in vehicles and buildings | Grade dependent | Named standard test |
| Formability | Whether it can be moulded | Thermally bonded grades only | Trial on the customer tool |
Absorption versus blocking
Absorptive materials convert sound energy into heat inside a porous structure; barriers block transmission with mass. Nonwoven is mostly an absorber, and its performance peaks at a frequency set by thickness and airflow resistance. A thin dense felt will beat a thick loose one at high frequency and lose at low.
If the requirement is a transmission loss figure, the answer is usually a composite, not a single nonwoven layer.
Why formability decides the grade
Automotive parts are moulded, so the fabric has to stretch and hold shape under heat. That requirement eliminates most carded grades and points to thermally bonded or needlepunched structures with a thermoplastic component. Building products rarely need this, which is why the same weight can be cheap for one buyer and impossible for another.
Moisture and fire, the two questions that stop projects
Insulation in a moist cavity grows mould, and insulation in a vehicle must pass a fire test. Both are specified, not assumed. Ask for the fire test the market requires and the moisture behaviour of the grade before the trial, because a grade that passes acoustics and fails fire is a wasted project.
Weight, thickness and the frequency you are fighting
Thin dense felts work at high frequency; thick lofted materials work lower down. If the noise problem is engine or compressor hum, a thin felt will disappoint regardless of weight. Start from the frequency band and the space available, then choose the structure.
Where the material sits in the assembly
An absorber behind a perforated panel behaves differently from one bonded to a solid surface. The mounting decides as much as the material, which is why acoustic projects are quoted with the assembly, not only the fabric.
Tell us the application and the acceptance test
The reply names a grade we can run, the tolerance we can hold and a lead time, or says plainly that we cannot make it.
Questions
Common questions
Can nonwoven replace a foam absorber?
In many automotive and appliance applications, yes, with a weight and thickness penalty. The comparison is per part, not per square metre, because moulding and assembly costs differ.
Do you supply fire retardant grades?
Grades can be produced with retardant treatment, and the fire test has to be named because pass criteria differ by market. We will tell you which test we can support rather than claim a generic rating.
What is the minimum order for a moulded automotive grade?
Higher than for a flat roll, because the trial has to run on the customer tool. Ask for a trial quantity and a programme price together.