In collision repair, auto body technicians will often come across auto foam in doors, quarter panel cells, or in bumpers. It appears in various cavities throughout a vehicle, as a hardened substance. Foams are strategically placed by automotive manufacturers for protection, noise reduction, safety, and a few other reasons as well. When working on a vehicle, it’s crucial to replace auto foam exactly where it was when it came out of the factory. Since vehicles are crash-tested with foam in place, failure to replace it could result in passenger safety being compromised.
Read on for a short overview of auto foam and what it does.
Types of Foam You may Encounter as an Auto Body Repair Technician
Different foams will be appropriate at certain times, depending on your purpose. Noise Vibration Harshness (NVH) foams are designed to control noise and vibrations during the operation of a vehicle. NVH foams can be rigid or flexible.
Flexible foams work to fill large cavities, controlling sound by preventing panels from fluttering. They can also function to block air movement or seal against water leaks. You can find flexible foam anywhere that two panels are close together, where the manufacturer wanted to prevent them from touching. You might be able to think of some of these places based on what you’ve seen in auto body schools. Rigid non-structural foam, or acoustic foam, is the second type of NVH foam. The density of rigid foam is much higher than flexible foams (by about 3 times).
Structural foam serves a different purpose. It reinforces the vehicle and helps to manage force in the event of a collision. If this foam is not replaced in a vehicle, the structural integrity of the automobile is compromised. This foam can be found in the torque box area, or within pillars and front lower rails.
Factors to Consider when Working with Foam for an Auto Body Repair Technician
It’s important when using auto foam to read the instructions on the product. Though sometimes technicians can get used to not needing to read the labels of products they know well, each product has unique properties that need to be taken into consideration, so there isn’t a one-size-fits-all approach that can apply to all foams.
Expansion rate is a major variable between products, for example. Some foams take 40 seconds to expand, whereas others may take 5 minutes. This affects how quickly you need to get foam into a cavity before it fully grows. Temperature is also an important variable to consider. A good rule of thumb is that at 21 degrees, foam will expand to about 10 times its liquid volume. This means that the temperature and humidity in your shop will affect the expansion of your product. You may work in different environments in your career as an auto body repair technician, so it’s worth keeping this in mind.
Foam Techniques for Graduates of Auto Body Schools
Damming is used to keep auto foams where they need to go. It’s not only important to find an access point to get auto foam into a cavity, but it’s also crucial that the foam is contained to where the manufacturer put it originally. This technique is sometimes done using a water balloon, which can fill a cavity while also preventing foam from expanding to an unwanted area.
Equalizing the cartridge is also important when applying foam. Cartridges should be equalized in an upwards motion, rather than downwards. This is because it causes air bubbles to float to the top, travelling out. It’s similar to getting air out of a syringe in a doctor’s office. Air pockets are an issue with the application of foam, as they can cause the product to react inappropriately and fail to harden. This creates not only an ineffective job, but a mess you’ll need to clean up.
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