• Your Repairs are Under Attack

    Unprotected steel

    Use Cavity Wax to Win the War on Corrosion

    • Results of unprotected welding during repairs
      Results of unprotected welding during repairs.

      When asked to identify the most prevalent causes of corrosion on vehicles today, the common responses are salt and corrosive chemicals, moisture or damaged coatings from stone chips. Most people don’t consider that collision repairs are commonly the cause of premature vehicle corrosion. Consider that the minute your repairs are completed, the repaired areas are under attack by the corrosion process. If your shop is neglecting the often forgotten step of applying a cavity wax to all newly welded areas, you are inviting corrosion to attack your repairs causing lost repeat customers, or worse yet, allowing the vehicle to become unsafe as corrosion eats away at the vehicle structure. It’s easy to spot vehicles that have been poorly protected from corrosion during collision repairs. When you see a vehicle that is rust free other than one panel that is rotting away, typically a quarter panel corroding around the wheel opening (Photo 1), it is usually due to poor corrosion protection practices during repairs. Unfortunately, this is not an uncommon sight because corrosion protection is one of the most neglected and misunderstood operations in the collision shop.

    • A recent 3M survey of body shops found that a large majority of repair technicians are not using any cavity wax to prevent post repair corrosion, and many that do use it are neglecting to apply it in critical areas where they should. A technician will take the time to perform a meticulous repair, but with just a few extra minutes can protect their hard work and ensure that the repair remains free of corrosion for the remaining years the vehicle will be on the road. The cosmetic consequences of poor corrosion protection can deter return business, but more importantly, the safety implications of failing to protect structural parts can be dangerous.

      The fact that the collision repair process may actually cause corrosion is understandable and often unavoidable because necessary processes such as welding, heating, or removal of protective coatings create corrosion hot-spots during repairs. Corrosion hot-spots are areas that are exposed to moisture, air, humidity, road chemicals or other corrosive elements. Unfortunately, the collision repair shop doesn’t have the same capabilities or equipment to exactly duplicate the factory corrosion protection processes. Automotive manufacturers take extreme care to ensure cars and trucks have been treated with corrosion resistant materials beginning with the application of specific galvanizing treatments (zinc) applied to mill-stock steel, and continuing with the use of high-quality heat-cured primers, sealers, and coatings designed to last the life of the vehicle. It is becoming uncommon to see the “rust buckets” that last five years and self-destruct even as the average age of a vehicle today has risen to 11.4 years.

    • Unprotected frame vs protected frame

      Unprotected frame vs. protected frame

    • Unprotected steel

      Unprotected steel

    • Continuous improvements at the factory are driven by consumer awareness and demands of safety and occupant protection. Increasing amounts of ultra- high strength steels (UHSS), some reaching 1500 MPa (217,556 PSI), are being engineered into the modern vehicle structures to protect passengers during collision impact. However, if the simple, yet critical, task of protecting the steel after welding operations during repairs is neglected, the entire process becomes flawed. Many modern repair facilities are equipped for and understand proper welding and repair techniques, yet they pay little or no attention to corrosion protection, especially internal cavity protection.

      At the factory, when welding is complete, the entire body structure is submerged in a bath of zinc phosphate which saturates all the welded seams and provides ultimate weld sealing and corrosion protection. Obviously, the collision repair shop cannot duplicate this process so they need to use the next best process to mitigate corrosion which is applying a cavity wax after the parts are assembled and welded. Cavity waxes are designed to protect enclosed cavities such as frame rails (Photo 2) and sectioned areas (Photo 3), but also to seep in between the welded flanges to duplicate the factory chemical dipping process as closely as possible.

      A high quality cavity wax should:

      • Wick into tight gaps between panels
      • Seal the gaps from the elements and encapsulate welding hot-spots
      • Remain tacky and flowable
      • Be self-healing by re-flowing into damaged or scratched areas

      Most OEMs recommend the use of a cavity wax, which may also be referred to as an anti-corrosion treatment/agent, for collision repairs. However, in the truck market only Volvo has issued standards on corrosion treatment for truck repairs. Many of the same standards offered by passenger car OEMs, however are applicable to a truck platform.

      Perhaps the BMW statement says it best, "the best repair is worth nothing if subsequent cavity protection measures are not conscientiously carried out". Generally speaking, it is a good idea to apply a cavity wax anywhere welding or heating has taken place unless it will be cosmetically unacceptable. It should also be sprayed into welded seams if no seam sealer will be applied to seal the joint such as on radiator supports. Why would you risk allowing corrosion to ruin your repair after all your effort to make a safe and invisible repair? Well, according to technicians that were surveyed, there are several reasons, some of which are:

      • It requires special equipment the shop doesn’t have
      • The equipment is usually in poor working order or clogged
      • The equipment won’t access the remote or enclosed areas easily
      • Cleaning the equipment is time consuming
      • The wands are too bulky to fit into small access or drain holes
    • Cavity Wax Plus 08852

      For these reasons 3M has launched a new product which will alleviate these road blocks. The new 3M™ Cavity Wax Plus uses a corrosion inhibiting formula that will wick into tight seams to protect welded areas and enclosed cavities with a film that will not harden and remain flowable to self-heal if scratched or abraded. When used with the 3M™ Cavity Wax Plus Applicator Wand Kit, 3M™ Cavity Wax Plus will deliver the right amount of flow and wicking to provide consistent and uniform protection for your repair. The easy to use aerosol can eliminates the need for using antiquated and messy bulk spray technology to apply corrosion protection to a vehicle. The wands can be easily cleaned by inverting the can and spraying until the wand is clean. The wand kit includes an 8” wand for easy to access areas such as radiator support seams, and two long wands (24” and 34”) to access enclosed areas such as frame rails and rocker panels. The wands are also very small in diameter so they can be easily inserted into small holes and tightly formed structures on the car body such as door frame drain holes or inner/outer side panel structures.

    Using corrosion products
    • The OEMs have vastly improved the corrosion resistance of their vehicles over the years. It is the obligation of the shop to provide the best possible corrosion protection during repairs to protect the customer’s substantial investment and not diminish the safety of the vehicle structure. Technicians spend valuable time training and work diligently to make safe and invisible repairs. It only makes sense to protect the repairs in the best possible way to preserve them for as long as possible by using corrosion protection products like cavity wax. With the latest improvements in products and equipment it requires minimal effort but will provide maximum protection and peace of mind.

      By Shawn Collins and Dennis Keicher; 3M AAD Technical Service

      For more information visit http://3mcollision.com/how-to/heavy-truck or contact heavydutytruck@mmm.com